Class Definition for Class 324 - ELECTRICITY: MEASURING AND TESTING

This subclass is indented under subclass 76.13. Subject matter including a device whose output is a series of discrete values representative of the values of an input at a series of points in time.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.24,	for sampling in a frequency spectrum analyzer.
76.38,	for sampling, per se, in analysis of complex waves.
76.42,	for sampling by frequency comparison in frequency of cyclic current or voltage.
76.58,	for sampling in digital output by phase comparison.

76.16

With counter:

This subclass is indented under subclass 76.13. Subject matter including a device capable of changing stages in a specified sequence upon receiving appropriate signals.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.48,	for counters in digital output by frequency comparison used to determine the frequency of cyclic current or voltage.
76.62,	for counters in digital output by phase comparison used to determine the frequency of cyclic current or voltage.

SEE OR SEARCH CLASS:

377,	Electrical Pulse Counters, Pulse Dividers, or Shift Registers: Circuits and Systems, subclass 19 where pulses are counted in systems for determining the value of some parameters.

76.17

With integrator:

This subclass is indented under subclass 76.13. Subject matter whereby summing of a signal is derived.

SEE OR SEARCH CLASS:

327,	Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 336+ for miscellaneous integrating circuits.
708,	Electrical Computers: Arithmetic Processing and Calculating, subclasses 823+ for analog integrators, per se.

76.18

With slope detector:

This subclass is indented under subclass 76.13. Subject matter comprising means to monitor the rise over the run in a wave.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.25,

for slope detection in frequency spectrum analyzers.

SEE OR SEARCH CLASS:

327,	Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 14+ for miscellaneous slope detecting circuits and subclass 170 for slope control of a pulse waveform.

76.19

Frequency spectrum analyzer:

This subclass is indented under subclass 76.12. Subject matter including means that show an energy distribution as a function of frequency for a given signal.

SEE OR SEARCH CLASS:

702,	Data Processing: Measuring, Calibrating, or Testing, subclasses 76+ for frequency spectrum analysis.

76.21

By Fourier analysis:

This subclass is indented under subclass 76.19. Subject matter wherein the energy distribution is taken at discrete harmonic components, i.e., harmonics, of the given signal.

SEE OR SEARCH CLASS:

702,	Data Processing: Measuring, Calibrating, or Testing, subclass 77 for Fourier analysis in a waveform measuring system.
708,	Electrical Computers: Arithmetic Processing and Calculating, subclasses 823+ for analog integrators, per se.

76.22	Real-time spectrum analyzer:
	This subclass is indented under subclass 76.19. Subject matter including a device which operates with sufficient speed that the energy distribution is determined within set timing limits.

76.23

With mixer:

This subclass is indented under subclass 76.19. Subject matter including a circuit that generates output frequencies equal to the sum or difference of two input frequencies.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.43,

for plural mixers used in frequency comparison for the determination of cyclic current or voltage.

SEE OR SEARCH CLASS:

455,	Telecommunications, subclasses 313+ for mixers, per se.

76.24

This subclass is indented under subclass 76.19. Subject matter including a device whose output is a series of discrete values representative of the values of an input at a series of points in time.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.15,	for sampling used in Amplitude distribution devices.
76.38,	for sampling, per se, in analysis of complex waves.
76.42,	for sampling by frequency comparison in determination of frequency of cyclic current or voltage.
76.58,	for sampling in digital output by phase comparison in determination of frequency of cyclic current or voltage.

76.25

With slope detector:

This subclass is indented under subclass 76.19. Subject matter comprising means to monitor the rise over the run in a wave.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.18,

for slope detection in amplitude distribution.

SEE OR SEARCH CLASS:

327,	Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 14+ for miscellaneous slope detecting circuits and subclass 170 for slope control of a pulse waveform.

76.26

Scanning-panoramic receiver:

This subclass is indented under subclass 76.19. Subject matter including a radio receiver that displays, on the screen of a cathode-ray tube, the presence and relative strength of all signals within a wide frequency range.

SEE OR SEARCH CLASS:

315,	Electric Lamp and Discharge Devices: Systems, subclasses 364+ for cathode-ray tube deflections circuits.
455,	Telecommunications, subclasses 145+ for panoramic display, per se.

76.27	With particular sweep circuit:
	This subclass is indented under subclass 76.26. Subject matter including a specific circuit which produces at regular intervals, an approximately linear, circular, or other movement of a beam in a cathode-ray tube.

76.28

Digital filter:

This subclass is indented under subclass 77.11. Subject matter wherein an input signal is operated on by means of digital circuitry to alter the frequency spectrum of the input signal.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.29,	for filtering in frequency spectrum analyzers.
76.31,	for parallel filters in frequency spectrum analysis.
76.44,	for filtering in frequency comparison used to determine the frequency of cyclic current or voltage.
76.68,	for filtering in phase comparison used to determine the frequency of cyclic current or voltage.

SEE OR SEARCH CLASS:

333,	Wave Transmission Lines and Networks, appropriate subclasses for filters and filtering in wave transmission lines and networks.
702,	Data Processing: Measuring, Calibrating, or Testing, subclass 17 for filtering or noise removal in a seismic prospecting system, subclasses 190+ for measured signal extraction or separation (e.g., filtering).

76.29

With filtering:

This subclass is indented under subclass 77.11. Subject matter including a network of resistors, inductors, or capacitors which offers comparatively little opposition to certain frequencies, while blocking or attenuating other frequencies.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.44+,	for filtering in frequency comparison for determination of the frequency of cyclic current or voltage.
76.68,	for filtering in phase comparison for the determination of the frequency of cyclic current or voltage.

SEE OR SEARCH CLASS:

333,	Wave Transmission Lines and Networks, appropriate subclasses for filters and filtering in wave transmission lines and networks.
702,	Data Processing: Measuring, Calibrating, or Testing, subclass 17 for filtering or noise removal in a seismic prospecting system, subclasses 190+ for measured signal extraction or separation (e.g., filtering).

76.31

Parallel filters:

This subclass is indented under subclass 76.29. Subject matter including parallel connected network of resistors, inductors, or capacitors which offers comparatively little opposition to certain frequencies, while blocking or attenuating other frequencies.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.28,	for digital filters in frequency spectrum analysis.
76.44,	for filtering in frequency comparison used to determine the frequency of cyclic current or voltage.
76.68,	for filtering in phase comparison used to determine the frequency of cyclic current or voltage.

SEE OR SEARCH CLASS:

333,	Wave Transmission Lines and Networks, appropriate subclasses for filters and filtering in wave transmission lines and networks.
702,	Data Processing: Measuring, Calibrating, or Testing, subclass 17 for filtering or noise removal in a seismic prospecting system, subclasses 190+ for measured signal extraction or separation (e.g., filtering).

76.32

This subclass is indented under subclass 76.31. Subject matter comprising any device which is intended to have an electrical current flow between two spaced electrodes, at least part of the path followed by the discharge being constituted by a gas, vapor, or vacuum.

SEE OR SEARCH THIS CLASS, SUBCLASS:

for space discharge device in frequency of cyclic current or voltage devices.

SEE OR SEARCH CLASS:

313,	Electric Lamp and Discharge Devices, for space discharge devices, per se.

76.33

Correlation:

This subclass is indented under subclass 77.11. Subject matter including means to measure the similarity of two or more signals.

SEE OR SEARCH CLASS:

708,	Electrical Computers: Arithmetic Processing and Calculating, subclasses 422+ for correlation in electric digital calculating computers.

76.34

This subclass is indented under subclass 76.33. Subject matter comprising any device which is intended to have an electrical current flow between two spaced electrodes, at least part of the path followed by the discharge being constituted by a gas, vapor, or vacuum.

SEE OR SEARCH THIS CLASS, SUBCLASS:

for space discharge device in frequency of cyclic current or voltage devices.

SEE OR SEARCH CLASS:

313,	Electric Lamp and Discharge Devices, for space.

76.35

With delay line:

This subclass is indented under subclass 77.11. Subject matter comprising a real or artificial transmission line or equivalent component that slows a signal for a predetermined length of time.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.54,

for delay line in phase comparison in frequency of cyclic current or voltage.

SEE OR SEARCH CLASS:

333,	Wave Transmission Lines and Networks, appropriate subclasses for delay lines in wave transmission lines and networks.

76.36

With optics:

This subclass is indented under subclass 77.11. Subject matter comprising lenses, prisms, or mirrors to be used in the frequency spectrum analyzer.

SEE OR SEARCH CLASS:

356,	Optics: Measuring and Testing, for optics measuring and testing, per se.
359,	Optics: Systems (Including Communication) and Elements, appropriate subclasses for optical systems and devices that may be used in measuring and testing.

76.37	Bragg cell:
	This subclass is indented under subclass 76.36. Subject matter comprising acousto-optic means to redirect light by the method of Bragg diffraction.

76.38

Frequency of cyclic current or voltage (e.g., cyclic counting etc.):

This subclass is indented under subclass 76.12. Subject matter including a device whose output is a series of discrete values representative of the values of an input at a series of points in time.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.15,	for sampling in amplitude distribution devices.
76.24,	for sampling in a frequency spectrum analyzer.
76.42,	for sampling by frequency comparison in frequency of cyclic current or voltage.
76.58,	for sampling in digital output by phase comparison.

76.39

This subclass is indented under subclass 76.11. Subject matter relating to the measuring of the frequency of an electric voltage or current which fluctuates in a periodic manner.

(1) Note. Generally, when an intangible electric voltage measurement occurs in a significant environment (for example, when the measurement is of the synchronizing frequency in a communication system) the class which provides for the environment also provides for the frequency measurement in that environment. The search should therefore, in appropriate instances, extend to other classes. An environment recited by name only is not considered to be significant.

(2) Note. The frequency measurement may be indicated in various manners, as in terms of frequency error, deviation, or average frequency over a period of time. The measurement and indication may be either qualitative or quantitative.

(3) Note. It is impossible to vary the frequency of a periodically varying voltage without concomitantantly varying its phase. Consequently, when the frequency changes slowly, it may be possible to indicate frequency by measuring phase angle. In those instances the search should extend to subclasses 76.77+, especially subclass 91, since synchronization is usually concerned with obtaining a zero phase angle rather than with obtaining a mere equality of frequency.

SEE OR SEARCH THIS CLASS, SUBCLASS:

160+,

for electrical measuring of speed, for example, the speed of rotating shafts or bullets, and for measuring the average frequency of random events, such as the occurrence of random electrical impulses and for timing means utilized to electrically determine the time interval between points spaced in time, when said points are not determined by the fluctuations of a periodically varying voltage, as when the points are determined, for example, by a randomly varying voltage or by the events at a race track.

76.12+,

for complex wave analysis, per se.

SEE OR SEARCH CLASS:

84,	Music, subclasses 454+ for tuning devices utilized in the tuning of musical instruments, some of which will measure the frequency of an unknown sound.
250,	Radiant Energy, subclass 250 for the measurement of radio or microwaves by an absorption wavemeter.
329,	Demodulators, subclasses 311+ for pulse demodulators or detectors; subclasses 315+ for frequency demodulators; and subclasses 345+ for phase demodulators.
331,	Oscillators, subclass 44 for oscillators provided with means or the method for calibrating the oscillator with respect to its generated frequency and subclass 64 for oscillators.
332,	Modulators, subclass 118 for frequency modulators having frequency measuring means and for the frequency meters, per se, when limited to use with modulation.
342,	Communications: Directive Radio Wave Systems and Devices (e.g., Radar, Radio Navigation), appropriate subclasses for radar systems. Note particularly subclasses 104+ for such systems (for example, by measuring the frequency shift due to the doppler effect) and subclasses 128+ for such systems which utilize frequency modulated waves.
361,	Electricity: Electrical Systems and Devices, subclasses 236+ for speed sensing and speed controlled systems, such as synchronizing systems.
368,	Horology: Time Measuring Systems or Devices, subclasses 15+ and 155+ for clocks which serve as standards in frequency measurements.
377,	Electrical Pulse Counters, Pulse Dividers, or Shift Registers: Circuits and Systems, appropriate subclasses for frequency of cyclic current or voltage in cycle counters or cycle counting.
702,	Data Processing: Measuring, Calibrating, or Testing, subclasses 75+ for frequency analysis, subclass 106 for signal frequency or phase correction.

76.41

Frequency comparison (e. g., heterodyne, etc.):

This subclass is indented under subclass 76.39. Subject matter having means to compare two frequencies with each other.

(1) Note. The two frequencies are usually, but not necessarily, sinusoidal.

(2) Note. One frequency, for example, may serve as a time base for an oscilloscope upon which the other frequency is displayed, or the two frequencies may be heterodyned to make a beat which has a mathematically determinable frequency with respect to the two frequencies.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.77+,

especially subclass 91, for this subject matter when the frequency comparison is for synchronizing purposes. See also (3) Note to subclass 76.39.

SEE OR SEARCH CLASS:

315,	Electric Lamp and Discharge Devices: Systems, subclasses 1+ for cathode-ray tube circuits that can be used in frequency comparison (e.g., oscilloscopes, etc.).
331,	Oscillators, for oscillators whose generated frequency can be varied or which can serve as frequency standards. By way of example, subclasses 37+ of Class 331 provides for beat frequency oscillator systems, and subclass 44 provides for oscillators with frequency calibration of oscillator.
334,	Tuners, appropriate subclasses for tuned networks for use in wave energy apparatus and comprising inductance and capacitance elements in circuit arrangement to form a resonant circuit and in which structure is provided for adjusting one or both of these elements for changing the mean resonant frequency of the circuit. Note especially subclasses 30+ for tuners combined with resonant indicators.
455,	Telecommunications, for this subject matter in combination with a radio receiving system, particularly subclasses 145+ for panoramic receivers.

76.42

Tuned mechanical resonator (e.g., reed, piezocrystal, etc.):

This subclass is indented under subclass 76.41. Subject matter including a device whose output is a series of discrete values representative of the values of an input at a series of points in time.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.15,	for sampling in amplitude distribution devices.
76.24,	for sampling in a frequency spectrum analyzer.
76.38,	for sampling, per se, in analysis of complex waves current, or voltage.
76.58,	for sampling in digital output by phase comparison.

76.43

With plural mixers:

This subclass is indented under subclass 76.41. Subject matter including more than one circuit that generates output frequencies equal to the sum and the difference of two input frequencies.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.23,

for mixers in frequency spectrum analyzers

SEE OR SEARCH CLASS:

455,	Telecommunications, subclasses 313+ for mixers, per se.

76.44

With filtering:

This subclass is indented under subclass 76.41. Subject matter including a selective network of resistors, inductors, or capacitors which offers comparatively little opposition to certain frequencies,while blocking or attenuating other frequencies.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.28,	for digital filters in frequency spectrum analysis.
76.29+,	for filtering in frequency spectrum analyzer.
76.31,	for parallel filters in frequency spectrum analysis.
76.68,	for filtering in phase comparison used to determine the frequency of cyclic current or voltage.

76.45	Bandpass:
	This subclass is indented under subclass 76.44. Subject matter that limits the range of frequencies that will be passed through a device.

76.46	Plural:
	This subclass is indented under subclass 76.44. Subject matter including more than one filter.

76.47

Digital output:

This subclass is indented under subclass 76.41. Subject matter comprising an output signal which represents the size of a stimulus or input signal in the form of a series of discrete quantities which are coded to represent digits in a system of numerical notation.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.55+,	for digital output by phase comparison in frequency of cyclic current or voltage.
76.82+,	for digital output in phase comparison, per se.

76.48

With counter:

This subclass is indented under subclass 76.47. Subject matter including a device capable of changing stages in a specified sequence upon receiving appropriate signals.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.16,	for counters in amplitude distribution devices.
76.62,	for plural counters in digital output by phase comparison.

SEE OR SEARCH CLASS:

377,	Electrical Pulse Counters, Pulse Dividers, or Shift Registers: Circuits and Systems, subclass 19 where pulses are counted in systems for determining the value of some parameters.

76.49

This subclass is indented under subclass 76.39. Subject matter having a mechanical resonating system and an electromechanical transducer to drive the mechanical resonating system in accordance with the electric voltage or current.

(1) Note. The mechanical resonator is usually a reed and its vibration can be visually observed, but it may be a quartz crystal whose motion is not visible or some other resonator.

SEE OR SEARCH CLASS:

333,	Wave Transmission Lines and Networks, subclasses 141+ and 186+ for electromechanical filters utilizing mechanical resonating systems.

76.51

By tuning (e.g., to resonance, etc.):

This subclass is indented under subclass 76.39. Subject matter having circuit which may be adjusted for resonance at a particular frequency or other predetermined condition.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.41+,	for this subject matter in combination with heterodyning means.
76.49+,	for this subject matter where the tuned current has a tuned mechanically resonant element.

SEE OR SEARCH CLASS:

250,	Radiant Energy, subclass 250 for this subject matter in combination with a radio or carrier wave communication frequency
334,	Tuners, appropriate subclasses for tuned networks for use in wave energy apparatus and comprising inductance and capacitance elements in circuit arrangement to form a resonant circuit and in which structure is provided for adjusting one or both of these elements for changing the mean resonant frequency of the circuit.
455,	Telecommunications, subclasses 154.1+ for indicator means combined with frequency selection means in a radio receiver.

76.52

By phase comparison:

This subclass is indented under subclass 76.39. Subject matter having angle relationship means as a part thereof, in order to perform the frequency measurement.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.77+,

for the phase comparison means, per se.

76.53	With phase lock:
	This subclass is indented under subclass 76.52. Subject matter comprising means of making the phase of an oscillator signal follow exactly the phase of a reference signal.

76.54

With delay line:

This subclass is indented under subclass 76.52. Subject matter comprising a real or artificial transmission line or equivalent component that slows a signal for a predetermined length of time.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.35,

for delay line in frequency spectrum analyzer.

SEE OR SEARCH CLASS:

333,	Wave Transmission Lines and Networks, appropriate subclasses for delay lines in wave transmission lines and networks.

76.55

Digital output:

This subclass is indented under subclass 76.52. Subject matter comprising an output signal which represents the size of a stimulus or input signal in the form of a series of discrete quantities which are coded to represent digits in a system of numerical notation.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.47+,	for digital output in frequency comparison.
76.82,	for digital output in phase comparison, per se.

76.56

With microwave frequency detection:

This subclass is indented under subclass 76.55. Subject matter comprising means to detect frequencies of 1000mhz plus.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.14,

for radiometers in amplitude distribution used in analysis of complex waves.

SEE OR SEARCH CLASS:

250,	Radiant Energy, subclass 250 for the measurement of radio or microwaves by an absorption wavemeter.
342,	Communications: Directive Radio Wave Systems and Devices (e.g., Radar, Radio Navigation), appropriate subclasses for directive radio wave systems and devices used in communication.

76.57	With tone detection:
	This subclass is indented under subclass 76.55. Subject matter comprising means to detect a sound sensation having pitch.

76.58

This subclass is indented under subclass 76.55. Subject matter including a device whose output is a series of discrete values representative of the values of an input at a series of points in time.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.15,	for sampling in amplitude distribution devices.
76.24,	for sampling in a frequency spectrum analyzer.
76.38,	for sampling used in analysis of complex waves.
76.42,	for sampling in frequency comparison used in determination of frequency of cyclic current or voltage.

76.59

With multiplexing:

This subclass is indented under subclass 76.55. Subject matter including a device for simultaneous transmission of two or more signals in either or both directions over the same transmission path.

SEE OR SEARCH CLASS:

370,	Multiplex Communications, for multiplex communications, per se.

76.61

With memory:

This subclass is indented under subclass 76.55. Subject matter comprising means to collect and hold information until it is needed.

SEE OR SEARCH CLASS:

365,	Static Information Storage and Retrieval, for memories, per se.

76.62

With counter:

This subclass is indented under subclass 76.55. Subject matter including devices capable of changing stages in a specified sequence upon receiving appropriate signals.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.16,	for counters in amplitude distribution devices.
76.48,	for counters in digital output by frequency comparison used in determining the frequency of cyclic current or voltage.

SEE OR SEARCH CLASS:

377,	Electrical Pulse Counters, Pulse Dividers, or Shift Registers: Circuits and Systems, subclass 19 where pulses are counted in systems for determining the value of some parameters.

76.63

Using register:

This subclass is indented under subclass 76.62. Subject matter including a device in which information is stored in and serially transferred through a storage medium.

SEE OR SEARCH CLASS:

235,	Registers, for mechanical registers, per se.
377,	Electrical Pulse Counters, Pulse Dividers, or Shift Registers: Circuits and Systems, for electrical registers, per se.

76.64	Plural:
	This subclass is indented under subclass 76.62. Subject matter comprising more than one counter.

76.65

This subclass is indented under subclass 76.55. Subject matter comprising any device which is intended to have an electrical current flow between two spaced electrodes, at least part of the path followed by the discharge being constituted by a gas, vapor, or vacuum.

SEE OR SEARCH THIS CLASS, SUBCLASS:

for space discharge device in frequency of cyclic current or voltage devices.

SEE OR SEARCH CLASS:

313,	Electric Lamp and Discharge Devices, for space discharge devices, per se.

76.66	With capacitive energy storage:
	This subclass is indented under subclass 76.52. Subject matter comprising conductors and dielectrics that store electrical energy.

76.67

This subclass is indented under subclass 76.66. Subject matter comprising any device which is intended to have an electrical current flow between two spaced electrodes, at least part of the path followed by the discharge being constituted by a gas, vapor, or vacuum.

SEE OR SEARCH THIS CLASS, SUBCLASS:

for space discharge device in frequency of cyclic current or voltage devices.

SEE OR SEARCH CLASS:

313,	Electric Lamp and Discharge Devices, for space discharge devices, per se.

76.68

With filtering:

This subclass is indented under subclass 76.52. Subject matter including a network of resistors, inductors, or capacitors which offers comparatively little opposition to certain frequencies, while blocking or attenuating other frequencies.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.28,	for digital filters in frequency spectrum analysis.
76.29+,	for filtering in frequency spectrum analyzer.
76.31,	for parallel filters in frequency spectrum analysis.
76.44,	for filtering in frequency comparison used to determine the frequency of cyclic current or voltage.

SEE OR SEARCH CLASS:

333,	Wave Transmission Lines and Networks, appropriate subclasses for filters and filtering in wave transmission lines and networks.
702,	Data Processing: Measuring, Calibrating, or Testing, subclass 17 for filtering or noise removal in a seismic prospecting system, subclasses 190+ for measured signal extraction or separation (e.g., filtering).

76.69	Current output proportional to frequency:
	This subclass is indented under subclass 76.52. Subject matter whereby the current is related to the frequency by a constant.

76.71	Nulling circuit:
	This subclass is indented under subclass 76.52. Subject matter comprising a circuit that indicates when current, voltage, or power is zero.

76.72

Qualitative output:

This subclass is indented under subclass 76.52. Subject matter whereby an output indicates conformance to specifications of a device.

(1) Note. This is usually a go or no situation.

76.73

With saturable device:

This subclass is indented under subclass 76.52. Subject matter comprising a magnetic-core reactor, the reactance of which is controlled by changing the saturation of the core by varying a superimposed unidirectional flux.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.75,

for inductive sensing used in determining the frequency of cyclic current or voltage.

SEE OR SEARCH CLASS:

307,	Electrical Transmission or Interconnection Systems, subclasses 401+ for Nonlinear Reactors Systems (e.g., Saturable), per se.

76.74	Deviation measurement:
	This subclass is indented under subclass 76.52. Subject matter comprising a device that measures the difference between the actual and specified values of a quantity.

76.75

Having inductive sensing:

This subclass is indented under subclass 76.39. Subject matter comprising detecting means which senses an inductance or detects the inducing of a voltage through mutual or electrostatic induction.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.73,	for a saturable device in by phase comparison used in determining the frequency of cyclic current or voltage.
200+,	for devices and methods to sense and indicate the sensing of a magnetic field, per se.

76.76

Phase comparison (e.g., between cyclic pulse voltage and sinusoidal current, etc.):

This subclass is indented under subclass 76.39. Subject matter comprising any device which is intended to have an electrical current flow between two spaced electrodes, at least part of the path followed by the discharge being constituted by a gas, vapor, or vacuum.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.65,

for space discharge device in digital output by phase comparison.

SEE OR SEARCH CLASS:

313,	Electric Lamp and Discharge Devices, for space discharge devices, per se.

76.77

This subclass is indented under subclass 76.11. Subject matter relating to the measuring of a phase relationship between an electric voltage or current which fluctuates in a periodic manner and another electric voltage or current which fluctuates in the same manner.

(1) Note. Generally, when the measurement of an intangible phase relationship occurs in a significant environment (for example, when the measurement is of the phase difference between voltages produced by two generators in an electric generating system) the search is in this class which provides for the phase measurement in that environment. The search should therefore, in appropriate instances, extend to other classes. An environment recited by name only is not considered to be significant.

(2) Note. The voltage or current usually fluctuates in a sinusoidal manner, but may fluctuate in any other periodic manner.

(3) Note. The phase measurement may be indicated in various manners, as in terms of phase angle, power factor, time lag or advance, or otherwise. The measurement and indication may be either quantitative or qualitative (as, for example, "lead" and "lag").

(4) Note. The two periodic voltages or currents need not be supplied to the system as inputs. For example, one of these periodic voltages may be supplied to the system as the unknown input while the other can be derived from the unknown input by an averaging process or can be supplied by a stable oscillator which is part of the system, or it can be supplied by a mechanically moving standard.

(5) Note. It is impossible to vary the phase of a periodically fluctuating voltage or current without concomitantly varying its frequency. Consequently, especially when phase angles vary rapidly, it may be possible to indicate phase angle by measuring frequency. In those instances the search should extend to subclasses 76.39+ of this class.

(6) Note. One of the voltages or currents may be of a different type than the other voltage or current; for example, one may be a sinusoidal voltage while the other may be a pulse current, or one of the voltages may be a harmonic of the other voltage and the measurement may be of the phase relationship between harmonics of the same frequency.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.52,	for phase comparison in frequency of cyclic current or voltage devices.
141,	and 142, for watt meters and voltmeters which do not indicate phase angle but respond to it.
160+,	for the measurement of phase angle between an electrical voltage or current and the angular position of a rotating machine which generates or is supplied by said voltage or current.

SEE OR SEARCH CLASS:

329,	Demodulators, subclasses 311+ for pulse demodulators using locally generated oscillations, subclasses 336+ for frequency demodulator employing phase shift, and subclass 346 for using locally generated oscillations.

76.78	Quadrature sensing:
	This subclass is indented under subclass 76.77. Subject matter comprising means to detect the state or condition of two related periodic functions or two related points separated by a quarter of a cycle, or 90 electrical degrees.

76.79

Feedback control, electrical:

This subclass is indented under subclass 76.77. Subject matter having electrical means to control a return path from an output terminal to an input terminal of at least one functional circuit device or circuit.

SEE OR SEARCH CLASS:

330,	Amplifiers, appropriate subclasses for feedback, per se.

76.81

Feedback control, mechanical:

This subclass is indented under subclass 76.77. Subject matter having mechanical means to control a return path from an output terminal to an input terminal of at least one functional circuit device or circuit.

SEE OR SEARCH CLASS:

330,	Amplifiers, appropriate subclasses for feedback, per se.

76.82

Digital output:

This subclass is indented under subclass 76.77. Subject matter comprising an output signal which represents the size of a stimulus or input signal in the form of a series of discrete quantities which are coded to represent digits in a system of numerical notation.

SEE OR SEARCH THIS CLASS, SUBCLASS:

76.47,	for digital output in frequency comparison in frequency of cyclic current or voltage.
76.55,	for digital output in by phase comparison in frequency of cyclic current or voltage.

76.83	Analog output:
	This subclass is indented under subclass 76.77. Subject matter having an output quantity which varies smoothly over a continuous range of values rather than in discrete steps.

77.11	Nonscanning:
	This subclass is indented under subclass 76.19. Subject matter wherein the frequency components of the spectrum are acquired simultaneously.

[List of Patents for class 324 subclass 84]

This subclass is indented under subclass 83. Subject matter having a wave guide.

SEE OR SEARCH CLASS:

333,	Wave Transmission Lines and Networks, subclasses 239+ , for wave guides, per se. Also consult the search notes to that subclass for the other classes which make provision for wave guides.

[List of Patents for class 324 subclass 85]

This subclass is indented under subclass 83. Subject matter having means to change the frequency of a voltage or current into another frequency which varies in correspondence therewith.

SEE OR SEARCH THIS CLASS, SUBCLASS:

79,	for frequency measuring using zero or countable beat heterodyne.
82,	for the subject matter of this subclass (85) used to measure frequency.

[List of Patents for class 324 subclass 86]

This subclass is indented under subclass 83. Subject matter in which one of the electric voltages or currents is obtained from a polyphase source.

(1) Note. In order that a disclosure be classified in this subclass, the polyphase source must be significantly related to the phase measurement. For example, the average phase angle of three phases of a three phase circuit may be compared with the phase of a single phase circuit. A polyphase source which supplies only a single phase voltage or current to the measuring equipment, without more, is not significantly related to the phase measurement.

SEE OR SEARCH THIS CLASS, SUBCLASS:

108,	for the measurement of positive, negative and zero sequence components of a three phase system.

[List of Patents for class 324 subclass 87]

This subclass is indented under subclass 83. Subject matter having a lamp or space discharge device or nonlinear device.

(1) Note. The lamp and space discharge device of this subclass are of the type which are classified elsewhere (see the Search Notes below) The nonlinear device is one whose voltage-current relationship is significantly nonlinear, as, for example, a thermistor, contact rectifier, thyrite resistor, transistor, saturable reactor or nonlinear condenser.

SEE OR SEARCH CLASS:

313,	Electric Lamp and Discharge Devices, see the Class Definition of Class 313 for lamp and space discharge device of this subclass (324/87). See (1) Note above.

[List of Patents for class 324 subclass 88]

This subclass is indented under subclass 87. Subject matter having a cathode ray tube.

(1) Note. The cathode-ray tube usually serves as an indicator, but not necessarily so.

SEE OR SEARCH CLASS:

313,	Electric Lamp and Discharge Devices, subclasses 364+ , for cathode-ray tubes, per se.
315,	Electric Lamp and Discharge Devices: Systems, subclasses 1+ for cathode-ray tube circuits of general application.

[List of Patents for class 324 subclass 89]

This subclass is indented under subclass 87. Subject matter having a space discharge device of the discharge control type.

(1) Note. The discharge may be controlled, for example, by means of a grid or by means of a magnetic field. The space discharge device may be of either the vacuum, gas or vapor type.

[List of Patents for class 324 subclass 90]

This subclass is indented under subclass 83. Subject matter having an indicating instrument of the type which has a stator element which produces a magnetic field by means of a supplied current.

(1) Note. The electrodynamometer instruments usually do not have a permanent magnetic field, but not necessarily so. They are, for example, of the ratio-meter type.

SEE OR SEARCH THIS CLASS, SUBCLASS:

144,	for the electrodynamometer instrument, per se.

[List of Patents for class 324 subclass 91]

This subclass is indented under subclass 83. Subject matter for indicating if two voltages or currents are in phase.

(1) Note. The indication may be quantitative or qualitative, as, for example, "lead" and "lag". The measurement must be of a phase angle and not of some unrelated quantity. Thus, for example, a mere voltmeter, even though designated a "synchroscope", is not classified here but is classified with the appropriate art.

SEE OR SEARCH THIS CLASS, SUBCLASS:

84,	through 90, for this subject matter where the synchroscope is of the type set forth in subclasses 84 through 90.

[List of Patents for class 324 subclass 92]

This subclass is indented under subclass 76. Subject matter having fluid means as a part thereof.

(1) Note. The fluid means must be significant to the electrical measurement or to the apparatus used in the measurement, and may be used, for example, as an expansible means in a thermal meter, as a lubricant, or as a cooling means.

SEE OR SEARCH THIS CLASS, SUBCLASS:

155,	for meter pivots and bearings.

SEE OR SEARCH CLASS:

73,	Measuring and Testing, subclasses 861+ for fluid rate of flow or volume meters, 290+ for fluid depth gages, and 700+ for fluid pressure gages.
137,	Fluid Handling, appropriate subclasses, for the subject matter of that class. Note subclasses 123+ for syphons, and subclasses 334+ for fluid handling with heating.

[List of Patents for class 324 subclass 93]

This subclass is indented under subclass 92. Subject matter in which the fluid is electrically conductive and having means to cause electricity to flow through the fluid.

(1) Note. The fluid is usually mercury, but may be any other conductive fluid, such as a molten alloy. Herein are found, inter alia, mercury type ampere hour meters.

[List of Patents for class 324 subclass 94]

This subclass is indented under subclass 93. Subject matter in which the fluid is electrolytic and having means to cause an electrolytic action to take place.

SEE OR SEARCH CLASS:

205,	Electrolysis: Processes, Compositions Used Therein, and Methods of Preparing the Compositions, appropriate subclasses for electrolysis utilized for electrochemistry and especially subclasses 775+ as the residual home for a process of electrolytic analysis or testing, per se.
252,	Compositions, subclass 62.2 for electrolytes utilized in electrical devices, such as electrolytic condensers and rectifiers.

[List of Patents for class 324 subclass 95]

This subclass is indented under subclass 76. Subject matter having a wave guide or electrically long line.

(1) Note. A cavity resonator is a special case of a wave guide.

SEE OR SEARCH THIS CLASS, SUBCLASS:

94+,	for similar subject matter utilized in electrical testing other than the measuring of electricity, per se.

SEE OR SEARCH CLASS:

333,	Wave Transmission Lines and Networks, subclasses 236+ , for long lines and wave guides, per se, and consult the class notes of Class 333 and the subclass definition notes for a definition of these terms.

[List of Patents for class 324 subclass 96]

This subclass is indented under subclass 76. Subject matter utilizing radiant energy means as a part thereof.

(1) Note. A voltage being measured may, for example, be applied to an electric light and the luminuous flux produced by the light may be taken as a measure of the voltage being measured.

SEE OR SEARCH CLASS:

250,	Radiant Energy, appropriate subclasses for the detections of nuclear or invisible radiant energy particularly subclasses 336.1+ for invisible radiant energy responsive electric signalling devices.
343,	Communications: Radio Wave Antennas, subclass 703 for antenna combined with structure which tells the magnitude of the signal energy flowing in, to or from the antenna, a significant relationship existing between the antenna and the measuring structure.
356,	Optics: Measuring and Testing, subclass 46 for incandescent standards, and subclasses 213+ for photometers.

[List of Patents for class 324 subclass 97]

This subclass is indented under subclass 96. Subject matter having means to direct the radiant energy in beams.

(1) Note. This subclass includes, for example, reflection galvanometers of the mirror type and pointer instruments having optical means to project an enlarged image of the pointer onto a scale.

SEE OR SEARCH THIS CLASS, SUBCLASS:

154,	for rotors that are mounted on filar suspensions.

[List of Patents for class 324 subclass 98]

This subclass is indented under subclass 76. Subject matter having means for actively bringing a state of balance between mechanical or electrical forces into existence.

(1) Note. This subclass includes, for example, potentiometers in which the potential of an unknown voltage is balanced against the potential of a standard cell.

(2) Note. The mere passive balancing that occurs in an instrument such as the D"Arsonval meter, where the spring restoring torque equals the rotor torque, is not the type of balancing which is the subject matter of this subclass. But balancing without deflection, for example, is found here.

[List of Patents for class 324 subclass 99]

This subclass is indented under subclass 98. Subject matter having automatic means for bringing about the state of balance.

SEE OR SEARCH CLASS:

318,	Electricity: Motive Power Systems, subclasses 560+ , and the classes referred to in the search notes to these subclasses for follow-up electric motor systems, also known as rebalancing and servo motor systems.
330,	Amplifiers, subclasses 144+ for amplifier systems including automatically variable impedance in the signal path.

[List of Patents for class 324 subclass 100]

100

This subclass is indented under subclass 99. Subject matter in which the result of the balancing operation is recorded.

SEE OR SEARCH THIS CLASS, SUBCLASS:

113,	for similar subject matter not having automatic balancing means.

SEE OR SEARCH CLASS:

346,	Recorders, subclass 31 and 32 for this subject matter.

[List of Patents for class 324 subclass 101]

101

This subclass is indented under subclass 76. Subject matter having a Wheatstone bridge and having means to indicate the current which results because of the unbalance.

SEE OR SEARCH THIS CLASS, SUBCLASS:

57+,	for Wheatstone bridges used to measure impedance.
98+,	for this subject matter having a Wheatstone bridge which is balanced.

SEE OR SEARCH CLASS:

323,	Electricity: Power Supply or Regulation Systems, subclass 365 , for miscellaneous Wheatsone bridge circuits and consult the search notes to that subclass for a list of the other classes which have provision for Wheatstone bridges.
330,	Amplifiers, subclasses 72 , 146 and 175, for amplifier systems wherein series arranged vacuum tubes are in the arms of a bridge, wherein at least one arm of a Wheatstone bridge, and wherein there is a Wheatstone bridge in the signal coupling circuit, respectively.

[List of Patents for class 324 subclass 102]

102

This subclass is indented under subclass 76. Subject matter which is responsive to a transient or which is used to determine some characteristic of a transient or some characteristic of a portion of a wave form of a cyclic wave.

(1) Note. This subclass includes, for example, the determination of the complete wave form of a transient, such as results when a short circuit occurs on a transmission line.

SEE OR SEARCH THIS CLASS, SUBCLASS:

100,	and 113, for recorders which are equally responsive to transients and steady state voltages.
103+,	for peak voltmeters or maximum current ammeters.
121,	for cathode ray oscilloscopes which are equally responsive to steady state and transient voltages.

[List of Patents for class 324 subclass 103]

103

This subclass is indented under subclass 76. Subject matter having means for indicating the demand for electricity, averaged over a set period of time, or having means for indicating the consumption of electricity exceeding a set minimum or having means for indicating the maximum or minimum value of the electricity.

(1) Note. The demand may be indicated in various manners, as by average demand over a period of time larger than the set period of time, maximum demand, integrated demand, or otherwise, and may be expressed in terms of watts, voltamperes or otherwise. The excess consumption may likewise be expressed in various manners, such as integrated excess or excess demand.

SEE OR SEARCH THIS CLASS, SUBCLASS:

102,	for the measurement of some characteristic of a transient, other than mere maximum or minimum.
116,	for multi-rate registering meters which register at different rates depending upon demand.
139,	for time controlled meters which do not measure demand.

[List of Patents for class 324 subclass 104]

104

This subclass is indented under subclass 103. Subject matter having means whose temperature is varied in accordance with the electricity being measured and having means, responsive to said temperature variation for indicating the demand, excess consumption, maximum, or minimum.

SEE OR SEARCH THIS CLASS, SUBCLASS:

92,	for this subject matter having fluid means, such as thermal expansion meters.

[List of Patents for class 324 subclass 105]

105

This subclass is indented under subclass 76. Subject matter having means which are significant because of some thermal relationship.

(1) Note. This subclass includes, for example, cooling features and means for compensating an instrument for changes in the ambient temperature. Thermally actuated meters are in indented subclass 106.

[List of Patents for class 324 subclass 106]

106

This subclass is indented under subclass 105. Subject matter having means whose temperature is varied in accordance with the electricity being measured and having means, responsive to said temperature variation, for indicating the result of the measurement.

(1) Note. This subclass includes, for example, hot wire ammeters of both the expansion or bimetallic type and the thermocouple type.

SEE OR SEARCH THIS CLASS, SUBCLASS:

92,	for this subject matter having fluid means, such as thermal fluid expansion meters.
104,	for this subject matter for indicating demand, excess, maximum or minimum.

SEE OR SEARCH CLASS:

374,	Thermal Measuring and Testing, subclasses 100+ , for thermometers, per se.

[List of Patents for class 324 subclass 107]

107

This subclass is indented under subclass 76. Subject matter responsive to the voltages or currents in a polyphase system.

(1) Note. A polyphase system is a group of alternating current circuits, usually interconnected, which enter or leave a region at more than two points of entry or exit, and which are so energized that in the steady state the alternating currents through the point of entry or exit and the alternating potential differences between them all have substantially equal periods, but have differences in phase and may have differences in wave form.

SEE OR SEARCH THIS CLASS, SUBCLASS:

140+,

for single phase systems of the three wire type, having means to measure the energy in such systems. Note that some of such metering systems are inherently capable of also measuring polyphase energy. Also consult the search notes to subclass 140.

108
	This subclass is indented under subclass 107. Subject matter for measuring the positive, negative or zero sequence of current of voltage in the polyphase system or responsive to one of these factors.

[List of Patents for class 324 subclass 109]

109

This subclass is indented under subclass 76. Subject matter having means for utilizing electrostatic attraction or repulsion or piezo-electric action in order to respond to the electricity.

SEE OR SEARCH THIS CLASS, SUBCLASS:

78+,	and 83+, for this subject matter when utilized to measure frequency or compare phase as, for example, in synchroscopes.

SEE OR SEARCH CLASS:

310,	Electrical Generator or Motor Structure, subclass 309 for electrostatic motors and subclasses 311+ for piezo-electric devices and systems, per se.
361,	Electricity: Electrical Systems and Devices, subclasses 271+ for electrostatic condensers, per se.

[List of Patents for class 324 subclass 110]

110

This subclass is indented under subclass 76. Subject matter for protecting the electric measuring apparatus or for combating attempts to cause the meter to read inaccurately.

(1) Note. This subclass includes, for example, meters combined with fuses to protect the meter against accidental overloads and meters that are provided with special circuit means to cause the meter to continue to register if the potential coil is disconnected by a customer of a utility company who is attempting to defraud the company.

SEE OR SEARCH THIS CLASS, SUBCLASS:

156,	for meters having casings which serve to protect the meter mechanically.

SEE OR SEARCH CLASS:

361,	Electricity: Electrical Systems and Devices, subclasses 659+ for meters having casings and similar structures to protect the meters mechanically.

[List of Patents for class 324 subclass 111]

111

This subclass is indented under subclass 76. Subject matter having means to store the electricity which is being measured.

(1) Note. This subclass relates to storage means, such as condenser banks, which store the electricity in such a manner that the original wave form can be recovered, and also relates to condensers which are used to integrate the electricity.

SEE OR SEARCH CLASS:

178,	Telegraphy, subclass 17.5 , for telegraph systems having storage means for temporarily holding signals.
315,	Electric Lamp and Discharge Devices: Systems, subclasses 8.51+ for cathode ray tube systems for accumulating or storing electrical pulse energy for later retrieval, and subclasses 84.51+ for similar electrical pulse storage systems utilizing electric space discharge devices of the gaseous type.
365,	Static Information Storage and Retrieval, appropriate subclass for the storage and retrieval of information. This class excludes the mere storage of control signals.

[List of Patents for class 324 subclass 112]

112

This subclass is indented under subclass 111. Subject matter in which the electricity is stored in an extended tape or wire or in a sheet medium.

(1) Note. This subclass relates to, for example, the storage of the electricity in a disk, similar to a phonograph record, and to the storage of the electricity in magnetic wire or tape.

SEE OR SEARCH CLASS:

360,	Dynamic Magnetic Information Storage or Retrieval, for magnetic recording or reproducing.
365,	Static Information Storage and Retrieval, appropriate subclass for the storage and retrieval of information. This class excludes the mere storage of control signals.
369,	Dynamic Information Storage or Retrieval, for dynamic storage of information signals.

[List of Patents for class 324 subclass 113]

113

This subclass is indented under subclass 76. Subject matter for recording the result of the measurement of the electricity.

(1) Note. Many of the Classes have provision for their own recording systems, consequently, in appropriate instances, the search for a recorder should extend to the class relating to the environment in which the recorder might be found.

SEE OR SEARCH CLASS:

346,	Recorders, appropriate subclasses, for this same subject matter. In Class 346 there is no subclass which relates specifically to the recording of electricity, per se, but the recorders are classified on the basis of the manner in which the record is made. Note subclass 150.2 in which an electric spark is utilized to mark a phenomenal record.
347,	Incremental Printing of Symbolic Information, subclasses 111+ for electric recorders comprising means for applying electricity to a medium for recording an image.

[List of Patents for class 324 subclass 114]

114

This subclass is indented under subclass 76. Subject matter having plural meters.

(1) Note. The meters may be of the same or of different kinds and may be separated or may be combined to one case.

SEE OR SEARCH THIS CLASS, SUBCLASS:

115,	for single meters which have plural ranges or plural scales.

SEE OR SEARCH CLASS:

340,	Communications: Electrical, subclasses 870.41 and 870.15 for telemetering systems having plural receivers or meters.
361,	Electricity: Electrical Systems and Devices, subclass 660 for switchboards having plural meters.

[List of Patents for class 324 subclass 115]

115

This subclass is indented under subclass 76. Subject matter having plural ranges, plural scales, or plural registration rates.

SEE OR SEARCH THIS CLASS, SUBCLASS:

114,	for meters having plural scales or plural ranges where both scales or both ranges are simultaneously usable, (i.e., where there are plural meters).

[List of Patents for class 324 subclass 116]

116

This subclass is indented under subclass 115. Subject matter having a register.

(1) Note. This subclass includes, for example, watt hour meters which register at one rate for an initial period and then register at a different rate for other periods.

SEE OR SEARCH THIS CLASS, SUBCLASS:

103,	for demand meters, per se, i.e., meters that indicate purely demand and not some quantity of which demand is but a factor.
139,	for time controlled meters of the registering type which do not register at plural rates.

[List of Patents for class 324 subclass 117]

117

This subclass is indented under subclass 76. Subject matter having magnetic means in which a significant amount of saturation occurs during the operation thereof.

(1) Note. This subclass relates, for example, to metering systems having magnetic amplifiers and to meters having saturated pole tips.

SEE OR SEARCH CLASS:

323,	Electricity: Power Supply or Regulation Systems, subclasses 249 , 302, 310, and 329, for magnetic amplifiers of the nonlinear type.
330,	Amplifiers, subclass 10 for amplifier systems wherein the active element is a saturable core reactor.

[List of Patents for class 324 subclass 118]

118

This subclass is indented under subclass 76. Subject matter having means to modulate the voltage or current being measured onto a carrier wave and having further means to demodulate the resulting modulating carrier wave into a replica of the original voltage or current.

(1) Note. This subclass relates, for example, to direct current voltmeters which measure a very small direct current voltage which small voltage is amplified in the modulator-demodulator apparatus so that it is large enough to actuate a conventional meter.

SEE OR SEARCH CLASS:

329,	Demodulators, appropriate subclasses for demodulators, per se.
330,	Amplifiers, subclass 10 for modulator-demodulator amplifiers, per se.
332,	Modulators, appropriate subclasses, for modulators.

[List of Patents for class 324 subclass 119]

119

This subclass is indented under subclass 76. Subject matter having a rectifier.

(1) Note. The rectifier may be used, for example, to change an alternating current input into a direct current output, or the rectifier may be used merely as a nonlinear element.

SEE OR SEARCH CLASS:

363,	Electric Power Conversion Systems, appropriate subclasses for miscellaneous rectifying systems.

[List of Patents for class 324 subclass 120]

120

This subclass is indented under subclass 76. Subject matter having means to transform the voltage or current to be measured into a different current or voltage and having means to measure said different voltage or current.

(1) Note. This subclass contains, for example, systems where a DC voltage is changed into an AC voltage which is measured as an AC voltage, systems wherein the input voltage is converted into a pulse voltage and systems wherein the input voltage is converted from one frequency into another frequency.

SEE OR SEARCH THIS CLASS, SUBCLASS:

118,	for this subject matter wherein the input voltage or current is first modulated and then demodulated.
119,	for this subject matter having a rectifier.

SEE OR SEARCH CLASS:

340,

Communications: Electrical, subclasses 870.01+ for telemetering systems having no significant measuring, testing or sensing of the condition to be telemetered. Some telemetering systems utilize current conversion means. Note indented subclasses 870.19+ for telemetering systems in which the value of the condition is represented by a pulse code.

[List of Patents for class 324 subclass 121]

121

This subclass is indented under subclass 76. Subject matter having a cathode-ray tube.

(1) Note. The cathode-ray tube may be an indicator as, for example, a cathode ray oscilloscope or a "magic eye" tube, or the cathode-ray tube may be a control tube of some type.

SEE OR SEARCH THIS CLASS, SUBCLASS:

88,	for this subject matter utilized to measure phase displacement between two voltages.

SEE OR SEARCH CLASS:

313,

Electric Lamp and Discharge Devices, subclasses 364+ , for cathode-ray tubes, per se.

315,

Electric Lamp and Discharge Devices: Systems, subclasses 1+ , for cathode- ray tubes circuits of general application. Note that Class 315 includes, among its cathode-ray tube systems, those systems in which an unknown voltage is applied to the deflecting means of the cathode-ray tube so that the unknown voltage may be observed. The system is not excluded from Class 315 unless some means is claimed to enable the desired information to be derived other than merely observing the trace of the ray on an unchartered luminous screen.

[List of Patents for class 324 subclass 122]

122

This subclass is indented under subclass 76. Subject matter having a gaseous discharge device.

(1) Note. A gaseous discharge device is defined as being a device having two spaced electrodes between which electricity flows and having either gas or vapor in the space between the electrodes.

(2) Note. This subclass includes, for example, spark gap volt meters and metering systems using a gaseous discharge device as a nonlinear impedance.

SEE OR SEARCH CLASS:

313,	Electric Lamp and Discharge Devices, subclasses 567+ for gaseous discharge devices, per se.
315,	Electric Lamp and Discharge Devices: Systems, appropriate subclasses for miscellaneous gas discharge device systems.

[List of Patents for class 324 subclass 123]

123

This subclass is indented under subclass 76. Subject matter having an amplifier or having a space discharge device.

SEE OR SEARCH THIS CLASS, SUBCLASS:

117,	for this subject matter utilizing magnetic saturation type amplifiers.
121,	for this subject matter when the space discharge device is a cathode-ray tube.
122,	for this subject matter when the space discharge device is a gaseous discharge device.

SEE OR SEARCH CLASS:

330,	Amplifiers, for amplifiers, per se.

[List of Patents for class 324 subclass 124]

124

This subclass is indented under subclass 123. Subject matter having an inverted amplifier.

(1) Note. An inverted amplifier is defined as one having an amplification factor which is less than unity. Usually this is achieved by connecting the input circuit to the plate of a vacuum tube and taking the output from the grid of a vacuum tube. The inverted amplifier acts as an attenuating circuit to couple the meter to the source of voltage or current being measured.

SEE OR SEARCH CLASS:

330,	Amplifiers, subclass 250 for inverted transistor amplifiers, and subclasses 160+ and 162+ for inverted amplifiers of the vacuum tube type.

[List of Patents for class 324 subclass 125]

125

This subclass is indented under subclass 76. Subject matter having means to control the mechanical vibrations which result because of inertia, elasticity, and damping or having means to control vibrations which arise outside or inside the measuring means.

(1) Note. This subclass includes, for example, instruments having "dead beat" characteristics.

SEE OR SEARCH THIS CLASS, SUBCLASS:

123,	for this subject matter having amplifier means with negative feed back control, for the purpose of controlling the inertia effects.

SEE OR SEARCH CLASS:

73,	Measuring and Testing, subclass 430 for instrument mechanism dampening, per se, subclasses 514.12+ for fluid or fluent material dampening of an inertial member in an acceleration measuring apparatus, and subclass 514.14 for vibration dampening in an inertial-type acceleration measuring apparatus.
248,	Supports, subclasses 560+ for resilient supports.

[List of Patents for class 324 subclass 126]

126

This subclass is indented under subclass 76. Subject matter having means for coupling the measuring device to the source of current or voltage being measured.

(1) Note. Such means, for example, may be an attenuator or an instrument shunt.

SEE OR SEARCH THIS CLASS, SUBCLASS:

115,	for this subject matter in instruments having plural ranges.
149,	for measuring instruments having mere prods, probes or other terminal structure without circuit elements other than conductors.

SEE OR SEARCH CLASS:

333,	Wave Transmission Lines and Networks, subclasses 24+ for coupling networks, per se.
338,	Electrical Resistors, subclass 49 for electrical resistors of the shunt type.

[List of Patents for class 324 subclass 127]

127

This subclass is indented under subclass 126. Subject matter in which the coupling means is a transformer.

(1) Note. The transformer, for example, may be of the type having a core which can be opened to admit a current carrying conductor.

SEE OR SEARCH THIS CLASS, SUBCLASS:

129,	for instruments having pole pieces which will admit a nonunitary input conductor without disconnecting or cutting said implement conductor.

SEE OR SEARCH CLASS:

336,	Inductor Devices, appropriate subclasses for the structure of transformers, per se. Of special interest are subclass 172 , for "Fractional turn" type inductive devices (including transformers), and subclasses 173+ and 175+ which include current transformers.

[List of Patents for class 324 subclass 128]

128

This subclass is indented under subclass 126. Subject matter in which the coupling means is a selective filter.

(1) Note. The filter may be a high pass, low pass or band pass filter.

SEE OR SEARCH CLASS:

333,	Wave Transmission Lines and Networks, subclasses 167+ , for wave filters, per se.

[List of Patents for class 324 subclass 129]

129

This subclass is indented under subclass 76. Subject matter having pole piece means so constructed that they will admit an input conductor without cutting or disconnecting said conductor.

(1) Note. This subclass includes, for example, "hook on" ammeters of the type not equipped with an integral transformer.

SEE OR SEARCH THIS CLASS, SUBCLASS:

127,	for similar subject matter utilizing a transformer of the split core type.

[List of Patents for class 324 subclass 130]

130

This subclass is indented under subclass 76. Subject matter having means for self-calibrating the instrument.

SEE OR SEARCH THIS CLASS, SUBCLASS:

74+,	for calibrating means for electric instruments, per se.

[List of Patents for class 324 subclass 131]

131

This subclass is indented under subclass 76. Subject matter in which the measuring instrument indications are of the suppressed zero type.

(1) Note. Suppressed zero refers to that condition of instrument in which the scale reading does not extend from zero to an upper value but rather from an intermediate value to an upper value.

[List of Patents for class 324 subclass 132]

132

This subclass is indented under subclass 76. Subject matter in which the measuring instrument indications are of the nonlinear type.

(1) Note. The instrument deflection, for example, may be related to the input current or voltage in a logarithmic manner.

[List of Patents for class 324 subclass 133]

133

This subclass is indented under subclass 76. Subject matter for giving a nonquantitative indication.

(1) Note. This subclass includes, for example, polarity testers and "hot-line" indicators.

(2) Note. A quantitative instrument may be modified into a nonquantitative instrument by merely omitting the scale. Consequently, in appropriate instances, the search should extend to the pertinent quantitative type subclass.

SEE OR SEARCH CLASS:

340,	Communications: Electrical, appropriate subclasses for similar subject matter. Also see the search note to Class 340 in the class definition of this class (324).
362,	Illumination, appropriate subclasses, for electric lamp luminaries, many of which could be used as nonquantitative indicators.

[List of Patents for class 324 subclass 134]

134

This subclass is indented under subclass 76. Subject matter having a commutator or having a reversing switch or having a pulsating switch.

(1) Note. This subclass includes, for example, DC watt hour meters.

SEE OR SEARCH CLASS:

200,	Electricity: Circuit Makers and Breakers, appropriate subclasses for the structure of switches, per se.
310,	Electric Generator or Motor Structure, appropriate subclasses, for motors having commutators.
361,	Electricity: Electrical Systems and Devices, subclasses 139+ for relay systems, per se.

[List of Patents for class 324 subclass 135]

135

This subclass is indented under subclass 134. Subject matter having a rotor which oscillates between two positions.

SEE OR SEARCH CLASS:

73,	Measuring and Testing, subclass 430 for instrument mechanism dampening, per se, subclasses 514.12+ for fluid or fluent material dampening of an inertial member in an acceleration measuring apparatus, and subclass 514.14 for vibration dampening in an inertial-type acceleration measuring apparatus.
310,	Electrical Generator or Motor Structure, subclasses 36+ for oscillating motors, per se.

[List of Patents for class 324 subclass 136]

136

This subclass is indented under subclass 76. Subject matter having a rolling ball or a rolling wheel.

(1) Note. The ball or wheel are usually part of an integrating mechanism, but may be part of a speed transmission.

SEE OR SEARCH CLASS:

33,	Geometrical Instruments, subclass 121 for area integrators, per se.
235,	Registers, appropriate subclasses, particularly subclasses 65 , 66 and 68, for calculating devices and machines having integrating features.

[List of Patents for class 324 subclass 137]

137

This subclass is indented under subclass 76. Subject matter having a rotor upon which torque is exerted by means of an electo-magnetic field which produces eddy current in the rotor.

(1) Note. This subclass includes, for example, the familiar AC integrating watt hour meter. The rotor is often known as a Ferraris disk.

(2) Note. The rotor in this subclass may rotate continuously or may rotate through only a certain angle as determined by the stiffness of a spring which restrains further rotation.

SEE OR SEARCH THIS CLASS, SUBCLASS:

152,	for this subject matter where the eddy current rotor is merely a drag disk.

SEE OR SEARCH CLASS:

310,	Electrical Generator or Motor Structure, subclasses 166+ for eddy current motors of general application.
318,	Electricity: Motive Power Systems, subclasses 727+ for eddy current motor systems of general application. Note particularly indented subclasses 781+, for eddy current motors which operate from a single phase source.

[List of Patents for class 324 subclass 138]

138

This subclass is indented under subclass 137. Subject matter having means to vary the time-phase relationship between two alternating magnetic fields.

(1) Note. The time-phase relationship, for example, may be adjusted so as to bring the alternating magnetic fields into time quadrature, or it may be adjusted so that they are slightly out of quadrature.

SEE OR SEARCH THIS CLASS, SUBCLASS:

148,	for other measuring means having phase shift means.

SEE OR SEARCH CLASS:

318,	Electricity: Motive Power Systems, subclass 729 for power-factor control of induction motor systems including eddy current motor systems.
323,	Electricity: Power Supply or Regulation Systems, subclasses 212 through 219for phase shifting means, per se.

[List of Patents for class 324 subclass 139]

139

This subclass is indented under subclass 76. Subject matter having rotary motor driving means which rotate constantly, independently of the electricity being measured, or having time control means or having means which oscillate.

(1) Note. Time control means may be, for example, a clock which rotates at a constant speed or an electric synchronous motor which rotates at a constant speed. Oscillating means may be means such as an anchor escapement or a stepping ratchet.

(2) Note. This subclass relates, for example, to integrating meters wherein an element periodically oscillates at an amplitude which is determined by the quantity to be integrated (variable stroke) or at a radius which is determined by that quantity (variable radius).

SEE OR SEARCH THIS CLASS, SUBCLASS:

103+,	for demand, excess, maximum or minimum meters which provide a final indication of which time is but a factor.
116,	for multi-rate registering meters which register at different rates in accordance with a function of time.
135,	for oscillating measuring means in which a pulsating or reversing switch is associated with the oscillating means.
136,	for variable radius type meters which utilize a rolling ball or wheel.

SEE OR SEARCH CLASS:

74,	Machine Element or Mechanism, appropriate subclasses, for ratchet mechanisms.
368,	Horology: Time Measuring Systems or Devices, for clocks and watches. Note subclasses 155+ , for those having electrical features.

[List of Patents for class 324 subclass 140]

140

This subclass is indented under subclass 76. Subject matter having plural inputs to the measuring means.

(1) Note. A single circuit can furnish plural inputs to the measuring means, since a single circuit can carry a voltage and a current independently of each other. Thus, the indented subclasses contain watt meters and volt-ampere meters of the type which are not found in subclasses above.

(2) Note. This subclass includes, for example, ratio meters and summation meters.

SEE OR SEARCH THIS CLASS, SUBCLASS:

62+,	for complete resistance measuring systems including, as a part thereof, ratio meters.

SEE OR SEARCH CLASS:

340,

Communications: Electrical, subclasses 870.01+ for telemetering systems for indicating at a remote point the value of a local condition. Note subclasses 870.11+ where the condition at plural localities is sensed. Note subclasses 870.19+ where the value of the condition is coded into a pulse type code.

[List of Patents for class 324 subclass 141]

141

This subclass is indented under subclass 140. Subject matter for measuring volt amperes.

(1) Note. The volt amperes may be either real or reactive. Reactive volt amperes are often referred to as volt vars,

SEE OR SEARCH THIS CLASS, SUBCLASS:

137+,

for this subject matter having an eddy current rotor.

[List of Patents for class 324 subclass 142]

142

This subclass is indented under subclass 140. Subject matter for measuring watts.

(1) Note. This subclass contains, for example, watt meters of the dynamometer type.

SEE OR SEARCH THIS CLASS, SUBCLASS:

134,	for this subject matter having a commutator or a reversing or pulsating switch.
137+,	for this subject matter having an eddy current rotor.

[List of Patents for class 324 subclass 143]

143

This subclass is indented under subclass 76. Subject matter having plural active motor elements.

(1) Note. The plural active motor element may be mounted on a single shaft to operate a single indicator, or they may be mounted on two shafts to operate two rotary arms whose variable point of intersection determines the final indication.

SEE OR SEARCH THIS CLASS, SUBCLASS:

114,	for plural meters.
115,	for a single meter having plural ranges or scales.

[List of Patents for class 324 subclass 144]

144

This subclass is indented under subclass 76. Subject matter having a stationary means to produce a magnetic field by the flow of electricity through a winding.

(1) Note. This subclass includes, for example, electrodynamometer type instruments having only a single input.

SEE OR SEARCH THIS CLASS, SUBCLASS:

134+,	for this subject matter having a rotor with a commutator or reversing or pulsating switch.
137+,	for this subject matter having an eddy current rotor.
140+,	for this subject matter having plural inputs.

SEE OR SEARCH CLASS:

310,	Electrical Generator or Motor Structure, subclasses 10+ , for dynamo electric structure of general application.

[List of Patents for class 324 subclass 145]

145

This subclass is indented under subclass 144. Subject matter having a core armature which is attracted by the magnetic field and which moves, under said attraction, along its own axis.

SEE OR SEARCH CLASS:

335,	Electricity: Magnetically Operated Switches, Magnets, and Electromagnets, subclasses 255+ for plunger type solenoids, per se.

[List of Patents for class 324 subclass 146]

146

This subclass is indented under subclass 144. Subject matter having a permanent magnet.

(1) Note. The permanent magnet may supplement the magnetic field produced by the electromagnet or it may be acted upon by the electromagnetic field.

SEE OR SEARCH THIS CLASS, SUBCLASS:

147,	for similar subject matter having soft instead of hard iron.

SEE OR SEARCH CLASS:

335,	Electricity: Magnetically Operated Switches, Magnets, and Electromagnets, subclasses 299+ for similar subject matter, not restricted to the measurement of electricity.

[List of Patents for class 324 subclass 147]

147

This subclass is indented under subclass 144. Subject matter having an iron rotor.

SEE OR SEARCH THIS CLASS, SUBCLASS:

146,	for this subject matter where the iron rotor is or becomes a permanent magnet under any conditions of operation.

[List of Patents for class 324 subclass 149]

149

This subclass is indented under subclass 76. Subject matter having a probe, a prod or a specific terminal.

SEE OR SEARCH THIS CLASS, SUBCLASS:

72.5,	for similar subject matter in combination with a high frequency testing device.
119,	for this subject matter having a rectifier in the probe.

SEE OR SEARCH CLASS:

361,	Electricity: Electrical Systems and Devices, subclass 668 for meter terminal or connector arrangements.
439,	Electrical Connectors, appropriate subclasses for an electrical terminal, per se.

[List of Patents for class 324 subclass 150]

150

This subclass is indented under subclass 76. Subject matter having a rotor which has a coil which is eccentrically mounted with respect to the axis of the rotor.

(1) Note. The coil, for example, may be of rectangular shape and the axis of the rotor may correspond with one of the sides of the rectangle.

SEE OR SEARCH THIS CLASS, SUBCLASS:

140,	for this subject matter having plural inputs, as in ratio-meters.

[List of Patents for class 324 subclass 151]

151

This subclass is indented under subclass 76. Subject matter having a permanent magnet.

(1) Note. This subclass relates, for example, to D"Arsonval type instruments and to magnetic suspensions for instrument rotors.

SEE OR SEARCH THIS CLASS, SUBCLASS:

146,	for this subject matter also having a magnetic field produced by an electromagnet.
171+,	for similar subject matter not restricted to the measurement of electricity.

SEE OR SEARCH CLASS:

310,	Electrical Generator or Motor Structure, subclass 90.5 for a bearing having a magnetic suspension.
335,	Electricity: Magnetically Operated Switches, Magnets, and Electromagnets, subclasses 302+ for permanent magnets, per se.

[List of Patents for class 324 subclass 152]

152

This subclass is indented under subclass 151. Subject matter in which the permanent magnet is associated with an eddy current means and the permanent magnet acts as a drag for the eddy current means.

(1) Note. The eddy current means usually is a disk rotor.

SEE OR SEARCH THIS CLASS, SUBCLASS:

103,	for excess type meters which utilize a hysteresis type brake (which has a constant counter-torque at all speeds) having a permanent magnet and for meters in which the torque on the drag magnet actuates an indicator by movement of the drag magnet.
137+,	for similar subject matter where an eddy current disk acts both as a motive element and a drag element.
139,	for meters having a rotor which is driven by a constant torque device and having a brake whose drag is determined by the electricity to be measured.

SEE OR SEARCH CLASS:

310,	Electrical Generator or Motor Structure, subclasses 103+ , for magnetic field type torque transmitting brakes and clutches.

[List of Patents for class 324 subclass 153]

153

This subclass is indented under subclass 76. Subject matter having a register.

(1) Note. A registering means is herein defined as being a device which converts a linear or rotational movement into a number which corresponds to the movement and is a measure thereof. Generally the register is provided with means for separately indicating the value of the several digits which go to make up the number that is a measure of the indication.

[List of Patents for class 324 subclass 154]

154

This subclass is indented under subclass 76. Subject matter having a rotor.

(1) Note. This subclass includes, for example, rotors provided with filar suspensions, rotors having means for setting them to zero, and rotors having means to balance them.

[List of Patents for class 324 subclass 155]

155

This subclass is indented under subclass 154. Subject matter having significant bearing or pivot structure.

(1) Note. A bearing or pivot is significant when it is claimed by more than name only or when it is disclosed as being significant.

SEE OR SEARCH THIS CLASS, SUBCLASS:

151,	for magnetic suspensions which decrease friction by decreasing bearing load.
403+,	for meters with fluid means, such as lubricating means.

SEE OR SEARCH CLASS:

310,	Electrical Generator or Motor Structure, subclass 90.5 for a bearing having a magnetic suspension.

[List of Patents for class 324 subclass 156]

156

This subclass is indented under subclass 76. Subject matter having a casing for the instrument.

SEE OR SEARCH CLASS:

73,	Measuring and Testing, subclass 431 , for this subject matter.
312,	Supports: Cabinet Structure, for miscellaneous casings.
361,	Electricity: Electrical Systems and Devices, subclasses 659+ for special meter casings, and subclasses 664+ for meter mounting arrangements.

[List of Patents for class 324 subclass 157]

157

This subclass is indented under subclass 76. Subject matter combined with some other type of subject matter.

(1) Note. The meter, for example, may be combined with a specific type of distribution system.

(2) Note. A meter in a specific environment, generally, but not invariably, is classified with the specific environment. Consequently, in appropriate instances, the search should extend to the class which relates to the environment.

SEE OR SEARCH THIS CLASS, SUBCLASS:

72,	for the measurement of electricity in a specific environment.
116,	for multi-rate registering meters which may, for example, be combined with two load circuits having loads of different tariff rates.

SEE OR SEARCH CLASS:

307,	Electrical Transmission or Interconnection Systems, appropriate subclasses for systems for distributing electricity.

[List of Patents for class 324 subclass 160]

160

This subclass is indented under the class definition. Subject matter wherein are provided processes or means to produce an electrical signal representative of the time rate of change of position (speed) of a physical element and to indicate, in response to said signal, said time rate.

SEE OR SEARCH CLASS:

73,	Measuring and Testing, subclasses 178+ , for navigational speed measuring devices such as ship’s logs, leeway incidence or rate of climb; subclasses 861+, for volume or rate of flow meters; subclasses 488+, for mechanical speed measuring devices and indented subclasses 519.01+, for permanent magnet type speedometers.
340,	Communications: Electrical, subclasses 441 and 446, for vehicle speed actuated signals and subclasses 670+, for speed actuated signals and alarms in general.
342,	Communications: Directive Radio Wave Systems and Devices (e.g., Radar, Radio Navigation), subclasses 104+ for radar type systems which determine the velocity of an object.
346,	Recorders, subclass 18 , for recorders combined with a speed indicator or alarm.
356,	Optics: Measuring and Testing, subclasses 27+ , for velocity or velocity/height measuring systems including optical sighting systems.
361,	Electricity: Electrical Systems and Devices, subclass 51 and subclasses 236+ for control systems responsive to speed.
700,	Data Processing: Generic Control Systems or Specific Applications, subclass 304 for speed control.
702,	Data Processing: Measuring, Calibrating, or Testing, subclasses 141 and 142+ for acceleration and speed measuring systems, respectively.

[List of Patents for class 324 subclass 161]

161

This subclass is indented under subclass 160. Subject matter in which means are provided for comparing one speed signal with another speed signal or a reference signal.

(1) Note. The comparison means is not necessarily electrical.

SEE OR SEARCH THIS CLASS, SUBCLASS:

79,	for comparison of the frequencies of two electrical signals.

SEE OR SEARCH CLASS:

307,	Electrical Transmission or Interconnection Systems, subclass 123 , for switching systems responsive to the differential speed between two bodies.
361,	Electricity: Electrical Systems and Devices, subclasses 243+ for the synchronization of rotating shafts which requires a comparison of the speeds of the shafts. Also consult the search notes to that subclass for a compilation of other pertinent classes.

[List of Patents for class 324 subclass 162]

162

This subclass is indented under subclass 160. Subject matter including means producing an electrical signal representative of the time rate of change of speed or a physical object.

(1) Note. This subclass relates to electrical accelerometers other than, for example, those which sense acceleration by means of an inertial element.

(2) Note. The means of this subclass may include means responsive to acceleration, per se, or means responsive to a speed signal to derive the acceleration.

SEE OR SEARCH CLASS:

73,	Measuring and Testing, subclasses 514.01+ , for means indicating acceleration including an inertial element. See (1) Note above.
307,	Electrical Transmission or Interconnection Systems, subclass 121 , for switching systems responsive to acceleration.
340,	Communications: Electrical, subclass 669 , for acceleration or deceleration responsive signals or alarms.
700,	Data Processing: Generic Control Systems or Specific Applications, subclass 304 for speed control.
702,	Data Processing: Measuring, Calibrating, or Testing, subclasses 141 and 142+ for acceleration and speed measuring system, respectively.

[List of Patents for class 324 subclass 163]

163

This subclass is indented under subclass 160. Subject matter in which means for producing a signal representative of speed includes means to convert mechanical motion into an electrical signal whose output amplitude is a function of the speed being measured, and in which the indicating means measures said amplitude.

SEE OR SEARCH THIS CLASS, SUBCLASS:

166+,

for electrical generators of speed signals whose frequency is a function of the speed being measured.

SEE OR SEARCH CLASS:

310,	Electrical Generator or Motor Structure, subclasses 10+ , for dynamoelectric generator structure.
322,	Electricity: Single Generator Systems, appropriate subclasses, for single dynamoelectric generator systems.

[List of Patents for class 324 subclass 164]

164

This subclass is indented under subclass 163. Subject matter in which the electrical generator includes a conductive, nonferromagnetic armature whose movement is representative of the speed being measured, means to induce an electric current in said armature and means responsive to the current to indicate the speed of the armature.

SEE OR SEARCH CLASS:

310,	Electrical Generator or Motor Structure, subclass 171 , for induction generator structure.
322,	Electricity: Single Generator Systems, subclass 47 , for induction generator systems.

[List of Patents for class 324 subclass 165]

165

This subclass is indented under subclass 163. Subject matter combined with means to indicate the sense of motion (e.g., forward or backward, clockwise or counter clockwise) within a given path, of the object whose speed is being measured.

SEE OR SEARCH CLASS:

33,	Geometrical Instruments, subclass 204 , for direction indicators in general which are responsive to some force.
116,	Signals and Indicators, subclasses 200+ , for mechanically actuated shaft rotation indicators.
307,	Electrical Transmission or Interconnection Systems, subclass 122 , for switching systems responsive to direction of rotation.
340,	Communications: Electrical, subclass 465 , for signal means for automatically indicating the direction of movement of a vehicle, and subclasses 671+, for signal means for indicating machine shaft rotation or direction.

[List of Patents for class 324 subclass 166]

166

This subclass is indented under subclass 160. Subject matter in which the signal producing means produces a periodic electrical signal whose frequency is a function of the speed being measured.

(1) Note. This subclass includes, for example, apparatus in which an electrical pulse is produced each time the moving object traverses a fixed increment of distance. The movement thus sensed may be either linear or angular (e.g., rotary).

SEE OR SEARCH THIS CLASS, SUBCLASS:

78+,	for the measurement of the frequency of cyclic electric currents of voltages.

[List of Patents for class 324 subclass 167]

167

This subclass is indented under subclass 166. Subject matter including electro-magnetic, indicator driving means energized by the speed signal to produce a rotating magnetic field whose rotation is synchronized with the frequency of the speed signal.

(1) Note. The rotating magnetic field may drive freely rotating armature or a restrained armature either of which is, in turn, connected to some means to indicate the speed of the rotating field and, thus, the object whose speed is being measured.

[List of Patents for class 324 subclass 168]

168

This subclass is indented under subclass 166. Subject matter in which the means for producing a signal includes an electrical circuit breaker actuated at a frequency representative of the speed being measured.

SEE OR SEARCH CLASS:

200,	Electricity: Circuit Makers and Breakers, subclasses 19.01+ , for periodically actuated switches.

169
	This subclass is indented under subclass 168. Subject matter in which the switch is also a component of an internal combustion engine ignition system.

170
	This subclass is indented under subclass 169. Subject matter wherein the speed measuring means is connected to the secondary circuit of the ignition system; the voltage fluctuations of the secondary circuit thereby producing the speed signal.

[List of Patents for class 324 subclass 171]

171

This subclass is indented under subclass 168. Subject matter combined with means to indicate the distance the object whose speed is being measured has traveled during the speed measuring interval.

(1) Note. This subclass includes revolution counters as well as odometers.

SEE OR SEARCH CLASS:

73,	Measuring and Testing, subclass 490 , for mechanical speed and distance measuring systems.

172
	This subclass is indented under subclass 166. Subject matter in which means for producing a speed signal includes a recording medium and means to move it at a speed proportional to speed being measured.

[List of Patents for class 324 subclass 173]

173

This subclass is indented under subclass 166. Subject matter in which the means for producing a speed signal included means producing a magnetic field and further means sensitive to changes in the field to produce an electrical signal.

SEE OR SEARCH THIS CLASS, SUBCLASS:

200,	for magnetic detectors and systems therefor.

SEE OR SEARCH CLASS:

73,	Measuring and Testing, subclass 519.01 for a speed measuring device using a magnetic drag cup.
310,	Electrical Generator or Motor Structure, subclasses 40+ , for rotary dynamoelectric generator structure.
322,	Electricity: Single Generator Systems, appropriate subclasses for single dynamoelectric generator systems.

[List of Patents for class 324 subclass 174]

174

This subclass is indented under subclass 173. Subject matter in which the means for producing a magnetic field includes a permanent magnet.

SEE OR SEARCH CLASS:

310,	Electrical Generator or Motor Structure, subclasses 152+ for rotary, dynamoelectric generator structure including permanent magnets.
322,	Electricity: Single Generator Systems, subclass 46 , for single dynamoelectric permanent-magnet generator systems.

175
	This subclass is indented under subclass 166. Subject matter in which means for producing a speed signal includes means responsive to radiant energy (i.e., electromagnetic or atomic radiation) to produce or alter an electric current.

[List of Patents for class 324 subclass 176]

176

This subclass is indented under subclass 160. Subject matter in which the means for producing the electric speed signal includes a variable circuit element whose impedance varies as a function of the position of the object in the path along which its speed is being measured.

(1) Note. The impedance of the circuit element of this subclass being a function of displacement, the current through the element may, for example, be differentiated with respect to time to produce the speed signal.

SEE OR SEARCH THIS CLASS, SUBCLASS:

178,	and the subclasses indented thereunder for systems including an element whose electrical characteristics change in response to the passage of an object.

SEE OR SEARCH CLASS:

73,	Measuring and Testing, subclasses 514.39+ , for apparatus including a mechanical speed indicating device with electrical means for sensing its indication, for example, a flyball governor with electrical means for sensing the radial displacement of the flyball.

[List of Patents for class 324 subclass 177]

177

This subclass is indented under subclass 160. Subject matter in which the means producing an electric speed signal is responsive to the supply voltage or current of an electric motor.

SEE OR SEARCH CLASS:

318,	Electricity: Motive Power Systems, and subclass 490 , for electric motors with signals, meters, recorders or testing devices.
388,	Electricity: Motor Control Systems, appropriate subclasses, together with art collection 928.1, for running-speed and acceleration control systems for responsive to terminal electromotive force.

[List of Patents for class 324 subclass 178]

178

This subclass is indented under subclass 160. Subject matter wherein the means for producing a speed signal includes means responsive to the passage (event) of an object past a plurality spaced locations.

(1) Note. This subclass includes, for example, systems for measuring the time taken by an object such as projectile or vehicle to move through a measured distance. The "event" being the passage of the object past the ends of the measured distance.

SEE OR SEARCH THIS CLASS, SUBCLASS:

181+,

for systems for measuring the duration of time intervals.

SEE OR SEARCH CLASS:

73,	Measuring and Testing, subclass 167 , for apparatus for testing ordinance and projectiles.
346,	Recorders, subclass 38 , for recorders actuated responsive to ordinance.

179
	This subclass is indented under subclass 178. Subject matter in which the means responsive to the passage of an object is sensitive to magnetic field variations caused by passage of the object through magnetic field.

[List of Patents for class 324 subclass 180]

180

This subclass is indented under subclass 178. Subject matter in which the means responsive to the passage of an object includes an electrical switch actuated directly by the object.

(1) Note. The switch of this subclass may be frangible.

SEE OR SEARCH CLASS:

200,

Electricity: Circuit Makers and Breakers, appropriate subclasses for switches or particular structure or type, particularly subclass 47 , for limit switches adapted to be actuated by the motion of a machine part, and subclass 61.41, for stationary switch structure having an actuator responsive to the passage of a transient object

[List of Patents for class 324 subclass 200]

200

MAGNETIC:

This subclass is indented under the class definition. Subject matter which includes apparatus to sense and indicate the sensing of a magnetic field and elements or subcombinations of apparatus to sense and indicate the sensing of the magnetic field where not elsewhere provided.

(1) Note. Method claims pertaining to the subject matter of this group of subclasses will be placed with the corresponding apparatus subclasses.

(2) Note. The term "elements" includes magnetic sensors, per se, and energized sensors not provided for in another class.

(3) Note. The apparatus to indicate includes a visible or latent recording of the result of a magnetic field sensing.

(4) Note. The magnetic field sensed may be a portion of a magnetic field or a portion of a magnetic field in a material.

(5) Note. Included in this group of subclasses are: the measuring or testing of magnetic fields, the measuring, testing, or sensing of material of metal or nonmetal by means of magnetic fields for electrical, magnetic, and other properties of the material, subcombinations of the apparatus to measure or test magnetic fields or materials by magnetic fields not provided for elsewhere, magnetic field sensors not classified elsewhere, supports for material tested by magnetic fields, and supports for magnetic field sensing devices.

(6) Note. This is the generic subclass for the location, identification, or testing of (1) metal ores, (2) unwanted metals, or (3) the presence of metal in a nonmetal environment. In these cases the metal is located, identified, or tested by its interaction with a magnetic field.

SEE OR SEARCH THIS CLASS, SUBCLASS:

51,	for short or open coil tests, the number of coil turns tests, and coil polarity tests.
55,	for transformer properties testing. 300+, for nuclear or electronic testing. 323+, for geophysical subsurface and surface testing. 376+, for core sample magnetic orientation testing.

SEE OR SEARCH CLASS:

164,	Metal Founding, subclass 450.5 for a metal casting apparatus including control means influenced by a magnetic sensor.
209,	Classifying, Separating, and Assorting Solids, subclass 8 for magnetizing or demagnetizing precedent to a separation, subclasses 38+ for the combination of a magnetic separation with another physical separation of a solid from a solid, subclasses 72+ for the magnetic testing and separation of objects from other objects, and subclasses 212+ for the separation of material by magnetic separation.
250,	Radiant Energy, subclasses 250+ for the detection of invisible electromagnetic energy and the testing of material by invisible electromagnetic radiation, subclasses 493.1+ for radiant energy generation and sources, and subclasses 505.1+ for radiation controlling means.
331,	Oscillators, subclass 44 for oscillators with frequency calibration or testing.
343,	Communications: Radio Wave Antenna, subclass 17.7 for radar systems with testing or calibrating, and subclass 703 for antennas with means to measure radiated antenna signal energy.
356,	Optics: Measuring and Testing, subclasses 33+ for the measurement of distance by light, subclasses 300+ for the examination of visible light by spectros copy, subclasses 138+ for angle or axial alignment testing, subclass 625 for menstruation or conation comparison, subclasses 401+ for color tests, and subclasses 213+ for the examination of visible light generally.
360,	Dynamic Magnetic Information Storage or Retrieval, subclass 31 for monitoring or testing the progress of recording.
455,	Telecommunications, subclasses 67.11 through 67.7, 115.1-115.4, and subclasses 226.1-226.4 for measuring and testing of communication equipment.

[List of Patents for class 324 subclass 201]

201

Susceptibility:

This subclass is indented under subclass 200. Subject matter wherein the apparatus to sense and indicate the sensing of a magnetic field is responsive to a magnetic field modified by material which has magnetic properties, the indication of the sensing being directly or indirectly representative of the ease with which the material can be magnetized.

(1) Note. The ratio of the intensity of magnetization of the material to the magnetic intensity of the field causing the magnetization of the material is known as susceptibility.

SEE OR SEARCH THIS CLASS, SUBCLASS:

204,	for apparatus to test gas, liquids, and fluent particles entrained in a fluid.
228,	for apparatus to test materials which require a magnetic test field including torque magnetometers.

[List of Patents for class 324 subclass 202]

202

Calibration:

This subclass is indented under subclass 200. Subject matter which includes means to present a known magnetic field to the apparatus to sense and indicate the sensing of the magnetic field so that the sensing and indication can be noted to see if the apparatus to sense and indicate gives the correct response to the sensed known magnetic field.

(1) Note. The known magnetic field may be a magnetic field of known magnetic intensity and type of wave, or the field can be a known magnetic field which is modified by a member whose effect on the field is known.

SEE OR SEARCH THIS CLASS, SUBCLASS:

74,	for testing and calibrating electric meters.
130,	for self-calibrating instruments which measure voltage or current.

SEE OR SEARCH CLASS:

73,	Measuring and Testing, subclasses 1.01+ for proving or calibrating test instruments.
250,	Radiant Energy, subclass 252.1 for methods of calibration or standardization of radiant energy test devices.
356,	Optics: Measuring and Testing, subclass 46 for electrical lamp circuits forming light standards, and subclasses 421+ for color charts.
374,	Thermal Measuring and Testing, subclasses 1+ for calibration or testing of a thermally responsive instrument.

[List of Patents for class 324 subclass 203]

203

Curie point determination:

This subclass is indented under subclass 200. Subject matter which includes means to create a magnetic field in which is placed a heated ferromagnetic material, the apparatus to sense and indicate being responsive to the magnetic field modified by the heated material to determine whether the heated material is at least at or below the critical temperature at which the heated material loses its ferromagnetism.

(1) Note. The apparatus to sense and indicate the magnetic field may be a magnet which functions to pass its magnetic flux through the material to induce magnetism in the material if its temperature is below the Curie point of the material to attract the material to the magnet.

SEE OR SEARCH THIS CLASS, SUBCLASS:

224,	for the temperature control of the test material or an element of the test circuit.
228,	for permanent magnets which locate ferromagnetic material by inducing magnetism in the material and noting the relative movement of the permanent magnet to material to be located.

SEE OR SEARCH CLASS:

148,	Metal Treatment, particularly subclasses 195+ for flame cutting or burning combined with sensing, subclasses 215+ for processes of carburizing or nitriding of metal combined with sensing or testing, subclass 240 for testing combined with reactive coating of metal, or subclasses 508+ for processes of measuring, testing, or sensing combined with treatment of solid or semi-solid metal to modify or maintain the internal physical structure (i.e., microstructure) or chemical property of metal. If casting, fusion bonding, machining, or working is combined with the treatment of solid or semi-solid metal to modify or maintain the internal physical structure (i.e., microstructure), there is a requirement that there be significant heat treatment as defined in section III, A, of the Class 148 definition.
335,	Electricity: Magnetically Operated Switches, Magnets, and Electromagnets, subclasses 209+ for magnets and electromagnets.
340,	Communications: Electrical, subclass 597 for a ferromagnetic temperature sensor in a signalling system; and subclasses 577 and 600 for ferromagnetic flame and radiation sensors, respectively, in a signalling system.
356,	Optics: Measuring and Testing, subclasses 43+ for optical pyrometers.
361,	Electricity: Electrical Systems and Devices, subclass 158 for temperature indicating instruments with systems for magnetizing, demagnetizing, or controlling a magnetic field.
374,	Thermal Measuring and Testing, subclass 176 for a thermometer having a ferromagnetic sensor.

[List of Patents for class 324 subclass 204]

204

Fluid material examination:

This subclass is indented under subclass 200. Subject matter which includes a magnetic field in which a gas or liquid material is placed for examination by the magnetic field, the apparatus to sense and indicate being responsive to the field modified by the gas or liquid material to give an indication of some property of the material examined.

(1) Note. Particles may be entrained in the gas or liquid examined magnetically in this subclass.

SEE OR SEARCH CLASS:

23,	Chemistry: Physical Processes, subclasses 232+ for gas analysis processes.
73,	Measuring and Testing, subclasses 23+ for gas analysis, particularly subclass 27 for paramagnetic gas analysis by magnetic and thermal means, and subclass 194 for magnetic induction type flow meters.
95,	Gas Separation: Processes, subclasses 27 and 28 for processes of gas separation using magnetism.
96,	Gas Separation: Apparatus, subclasses 1+ for magnetic separation means for gas separation.
209,	Classifying, Separating, and Assorting Solids, subclasses 38 through 40for the magnetic separation of a solid from a solid, liquid, or a gas combined with another type of separation, and subclass 232 for the separation of a solid from a solid or liquid magnetically when in a fluid suspension.
210,	Liquid Purification or Separation, subclass 695 for processes of precipitation of a solid from a liquid by magnetic means, and subclasses 222+ for apparatus to magnetically treat material under the class definition.
250,	Radiant Energy, subclass 306 for the inspection of liquids by electrically charged particles, subclasses 343+ for the infrared examination of contained fluent material, subclass 356.1 for flow metering by radiant energy apparatus, subclass 357.1 for fluent material level examination by radiant energy, subclasses 373+ for the ultraviolet examination of contained fluent material, subclasses 383+ for the examination of emissive fluent type or radiation transmissive fluent material by ionized gas-type detector, subclasses 428+ for fluent material containment, support, or transfer means combined with radiant energy treatment, subclasses 564+ for photocell sensing of fluent material, and subclasses 573+ for optical or prephotocell systems to sense fluent material by photoelectric means.
356,	Optics: Measuring and Testing, subclass 70 for oil testing by visible light; subclass 398 for the inspection of container content by light; subclasses 409+ for color transmission testing of fluids; and subclasses 441+ for the examination of liquid particle suspensions by visible light.
422,	Chemical Apparatus and Process Disinfecting, Deodorizing, Preserving, or Sterilizing, subclasses 83+ for analysis of apparatus involving a chemical reaction.

[List of Patents for class 324 subclass 205]

205

Permanent magnet testing:

This subclass is indented under subclass 200. Subject matter which involves the testing of permanent magnets which have their own static magnetic field, the apparatus to sense and indicate the sensing of the field including a field sensing member placed in the field and an indicator responsive to the member.

(1) Note. The sensing member may be a fixed or movable permanent magnet, a member that can be temporarily magnetized by the field of the tested magnet, an electrically conductive member that causes eddy currents in response to the field, or a sensing coil that is fixed or movable.

SEE OR SEARCH THIS CLASS, SUBCLASS:

228,	for the testing of material by a magnetic field and the sensing of the material modified field by a nonelectrically energized field sensor.
256,	for the sensing of a magnetic field by a movable energized sensing coil magnetometer.
259,	for a magnet or magnet member sensor type magnetometer.

SEE OR SEARCH CLASS:

335,	Electricity: Magnetically Operated Switches, Magnets, and Electromagnets, subclasses 302+ for permanent magnets.

[List of Patents for class 324 subclass 206]

206

Movable random length material measurement:

This subclass is indented under subclass 200. Subject matter which includes a movable magnetizable member and a magnetic marking means to form magnetic field marks on the member in the direction of its movement, and wherein the apparatus to sense and indicate the sensing of the magnetic field is responsive to the marks and indicates the sum of the marks as an indication of its length or compares the sensed marks to indicate a deviation of its length between markings.

SEE OR SEARCH CLASS:

33,	Geometrical Instruments, subclasses 732+ for feeding a fabric or cord through a fabric or cord distance measuring device in contact with the fabric or cord.
226,	Advancing Material of Indeterminate Length, subclasses 10+ for control means actuated in response to marks on advancing material.
242,	Winding, Tensioning, or Guiding, subclass 431 for a winding machine under the control of an electrical property of an article being wound, and subclasses 334.3, 334.4, 485.5, 487.5, 534+, and 563+ for a detector or stop which may measure length of an elongated material being wound or unwound.
333,	Wave Transmission Lines and Networks, subclasses 141+ for electromechanical transducer-type time delays.
360,	Dynamic Magnetic Information Storage or Retrieval, subclasses 1+ for recording or reproducing from an element of diverse utility, and subclass 6 for recording or playback apparatus combined with metering or sensing.

207.11

Displacement:

This subclass is indented under subclass 200. Subject matter which includes a device to note the change in position of one member with respect to another member, the device having means to create a magnetic field and having either (1) the means supported by one of the members, or (2) the members included in a magnetic circuit in the magnetic field, the apparatus to sense and indicate the sensing of the magnetic field being responsive to the change in the magnetic field to note the movement of one of the members with respect to the other member.

SEE OR SEARCH CLASS:

178,	Telegraphy, subclasses 18.01+ for position determining or writing (e.g., hand writing analysis).
341,	Coded Data Generation or Conversion, subclass 15 for a displacement responsive magnetic pattern element with a digital code signal generating circuit.

207.12	Compensation for measurement:
	This subclass is indented under subclass 207.11. Subject matter which includes a device, circuit or circuit component that corrects an undesirable condition which affects the displacement measurement.

207.13	Having particular sensor means:
	This subclass is indented under subclass 207.11. Subject matter which includes a device having a specific function or structure that detects the presence of, or a change in the level of a magnetic field.

207.14

Diverse sensors:

This subclass is indented under subclass 207.13. Subject matter in which two or more different types of sensors are used simultaneously or alternatively.

(1) Note. Plural measurements involve two or more different types of measurements such as linear and rotary, whereas diverse measurement includes two or more sensors for one or more measurements.

SEE OR SEARCH THIS CLASS, SUBCLASS:

207.23,

for plural measurements.

207.15

Inductive:

This subclass is indented under subclass 207.13. Subject matter wherein sensing device is an inductor.

SEE OR SEARCH CLASS:

336,	Inductor Devices, appropriate subclasses for inductors not specifically used in testing.

207.16	Electrically energized:
	This subclass is indented under subclass 207.15. Subject matter containing one or more sources of electrical energy for energizing sensor means to produce a magnetic field.

207.17	Separate pick-up:
	This subclass is indented under subclass 207.16. Subject matter in which a magnetic sensor is a receiver means that generates a signal in response to an electrically energized transmitter.

207.18

Differential type (e.g., LVDT):

This subclass is indented under subclass 207.16. Subject matter wherein (1) a sensor measures two separate stimuli and provides an output proportionate to the difference between them or (2) a transformer uses two or more primary sensor signals, or (3) a transformer uses two or more secondary sensor signals to provide a differential output.

(1) Note. LVDT is an abbreviation meaning linear variable differential transformer.

207.19	Differential bridge circuit:
	This subclass is indented under subclass 207.16. Subject matter wherein an imbalance in a bridge circuit is based upon the difference between at least two inductive sensors forming at least two legs of the bridge circuit.

207.2

Hall effect:

This subclass is indented under subclass 207.13. Subject matter wherein the sensor uses the Hall effect to give an output voltage proportional to magnetic field strength.

(1) Note. Hall effect is the description given to the following phenomena: when a conductor, through which a current is flowing, is placed in a magnetic field, a potential difference is generated between the two opposed edges of the conductor in the direction mutually perpendicular to both the field and the conductor.

SEE OR SEARCH THIS CLASS, SUBCLASS:

251,	for hall plate magnetometers.

SEE OR SEARCH CLASS:

330,	Amplifiers, subclass 6 for hall effect amplifiers.
338,	Electrical Resistors, subclass 32 for resistance value responsive to a condition wherein magnetic field or compass utilizes Hall effect.

207.21

Magnetoresistive:

This subclass is indented under subclass 207.13. Subject matter wherein a sensor is a semiconductor material in which the electrical resistance is a function of the applied magnetic field.

SEE OR SEARCH THIS CLASS, SUBCLASS:

252,	for Hall plate magnetoresistive magnetometer.

SEE OR SEARCH CLASS:

338,	Electrical Resistors, subclass 32 for a magnetic field or compass with resistance value responsive to a condition.

207.22

Having particular sensed object:

This subclass is indented under subclass 207.11. Subject matter in which a specific configuration or structure of an object is such that its motion may be detected by measuring a change of a magnetic property associated with the object.

(1) Note. This subclass includes sensor attachments that move with the device under test.

207.23

Plural measurements (e.g., linear and rotary):

This subclass is indented under subclass 207.11. Subject matter wherein there are two or more different types of position measurement.

SEE OR SEARCH THIS CLASS, SUBCLASS:

207.14,

for measurements using two or more sensors.

207.24	Linear:
	This subclass is indented under subclass 207.11. Subject matter in which motion in a straight line is determined.

207.25	Rotary:
	This subclass is indented under subclass 207.11. Subject matter in which (1) angular displacement is determined or (2) deviation from an angular path is measured.

207.26	Approach or retreat:
	This subclass is indented under subclass 207.11. Subject matter in which the (1) the sensing device gives an indication when approaching or being approached by a magnetic field, or (2) the sensing device gives an indication when retreating or being retreated by a magnetic field, or (3) an object approaches or retreats from the sensor"s magnetic field.

[List of Patents for class 324 subclass 209]

209

Stress in material measurement:

This subclass is indented under subclass 200. Subject matter which includes apparatus to note the strain within material having means to form a magnetic field in which the material is placed, or means to form a magnetic field in the material, the apparatus to sense a magnetic field and indicate the sensing of the magnetic field senses the magnetic field modified by the material or the field produced in the material and indicates the result of the test, the indication being a measure of the strain in the material as a result of some type of force imparted to or within the material.

(1) Note. The means to impart the force to the material may or may not be claimed.

(2) Note. Compressional, tensional, shear, or torsional physical force is used to impart strain to the material.

(3) Note. The material tested can be examined for residual strain after the applied force is removed from the material, or the material can be examined for strain resulting from the applied force.

(4) Note. Excluded are claims to sense the internal strain of a magnetic sensor which is an indication of the force applied to the sensor and torque or torsion sensing devices relying on magnetic characteristics.

(5) Note. Claims testing the magnetostrictive effect of material are classifiable here.

SEE OR SEARCH CLASS:

73,

Measuring and Testing, subclasses 136+ and 141+ for sensing the internal strain of a magnetic sensor which is an indication of the force applied to the sensor and torque or torsion sensing devices relying on magnetic characteristics; subclass 779 for stress or strain measuring system having an inductive or magnetic sensor mechanically coupled to the specimen and subclasses 862+ for dynamometers including subclasses 862.381+ for the measurement of force by magnetic load cells.

356,

Optics: Measuring and Testing, subclasses 32+ for material strain analysis of material by visible light.

[List of Patents for class 324 subclass 210]

210

Magnetic information storage element testing:

This subclass is indented under subclass 200. Subject matter which includes a magnetic recorder element to be tested magnetically, means to create a magnetic test signal to be either sensed by the tested element or recorded on the tested element, the said apparatus to sense the magnetic field either (1) being or including the tested element itself, or (2) sensing the recorded test signal on the tested element, the said apparatus to indicate the sensing of the test magnetic signal being responsive to the apparatus to sense the signal or to the recorder element tested.

(1) Note. The testing device is not integral with the information device tested.

(2) Note. A prerecorded test signal on a magnetic storage element tested may take the place of the means to create a test signal.

SEE OR SEARCH CLASS:

29,	Metal Working, subclass 603 for processes of making magnetic recording reproducing transducers.
346,	Recorders, subclass 33 for a magnetic recorder with an external operating means, and subclass 74.2 for magnetic pictorial or graphic recorders.
365,	Static Information Storage and Retrieval, subclass 201 for specifics of a memory which are tested for defects or erroneous information.
702,	Data Processing: Measuring, Calibrating, or Testing, subclasses 108+ for testing system, particularly subclasses 117+ for testing of circuit.
714,	Error Detection/Correction and Fault Detection/Recovery, subclasses 718+ for diagnostic testing of memory systems.

[List of Patents for class 324 subclass 211]

211

Memory core storage element testing:

This subclass is indented under subclass 210. Subject matter wherein the element tested is a nonmoving toroid magnetic memory element.

SEE OR SEARCH CLASS:

209,	Classifying, Separating, and Assorting Solids, subclass 81 for the automatic magnetic testing and sorting of static cores.
365,	Static Information Storage and Retrieval, subclasses 129+ for toroid magnetic elements in a memory system.

[List of Patents for class 324 subclass 212]

212

Dynamic information element testing:

This subclass is indented under subclass 210. Subject matter wherein the element tested is a movable magnetic storage element.

(1) Note. Here are magnetic tape, drum, disc, and wire storage elements.

SEE OR SEARCH CLASS:

360,	Dynamic Magnetic Information Storage or Retrieval, subclass 31 for testing the progress of recording.

[List of Patents for class 324 subclass 213]

213

Magnetic recording medium on magnetized object records object field:

This subclass is indented under subclass 200. Subject matter wherein the apparatus to sense and indicate the sensing of a magnetic field includes a magnetic recording medium applied to magnetized material so that any stray or leakage field from the magnetized material induces a magnetic field in the recording medium which is indicative of flaws in the material tested.

(1) Note. The magnetic field of the recording medium is latent and requires, for example, magnetic particles to form a visible image of the induced field on the recording medium.

SEE OR SEARCH THIS CLASS, SUBCLASS:

210+,	for the testing of magnetic information storage elements.
214+,	for testing of magnetic fields or magnetized materials by magnetic particles.

SEE OR SEARCH CLASS:

209,	Classifying, Separating, and Assorting Solids, subclass 215 and other related subclasses for separation of flawed articles from good magnetized articles based upon the change in the magnetic field of magnetized article due to flaws in the article.
252,	Compositions, subclass 62.52 for flaw detections compositions.
346,	Recorders, subclass 33 for the recording of flaws in response to an external flaw detection device.

[List of Patents for class 324 subclass 214]

214

By paramagnetic particles:

This subclass is indented under subclass 200. Subject matter which includes a magnetic field detector composed of particles including ferromagnetic material which, when placed in the magnetic field, align themselves in the direction of the tested magnetic field to form a visual representation of the tested magnetic field.

(1) Note. The particles may be of iron, nickel, or cobalt material.

(2) Note. The particles when in the magnetic field act as both a magnetic field detector and a visual indicator of the pattern of the tested field at the location of the field between the magnetic poles or at the location of the field discontinuities.

SEE OR SEARCH THIS CLASS, SUBCLASS:

200,	for the sensing and plotting of magnetic fields.

SEE OR SEARCH CLASS:

252,	Compositions, subclass 62.51 for magnetic compositions useful for magnetic purposes.

[List of Patents for class 324 subclass 215]

215

With pattern enhancing additive:

This subclass is indented under subclass 214. Subject matter wherein some chemical, composition, material, or mixture of materials is added to the paramagnetic particles to enhance the viewing of the particles with respect to the object tested after the particles are magnetized and attracted to the magnetized object tested.

(1) Note. The chemical, composition, material, or mixture may be directly placed on or diffused some way into the magnetic particles, or may form a dry mixture with the particles or a liquid vehicle for the magnetic particles.

(2) Note. Coatings, dyes, and liquid and solid mixtures of material with the particles are in this subclass.

(3) Note. Fluorescent and phosphorescent material which require radiation on these materials to emit light are here as well as materials which have optical properties to permit the particles to be more easily distinguished from the object and the surroundings of the test.

[List of Patents for class 324 subclass 216]

216

Flaw testing:

This subclass is indented under subclass 214. Subject matter wherein the paramagnetic particles are used to test an object made of magnetic material and which includes means to magnetize the object to be tested to cause the parmagnetic particles, when upon the magnetized object, to become magnetized and adhere to the magnetized object or at a location where a discontinuity occurs when present in the object, the adhering magnetized particles arranging themselves in the pattern of the flux exiting from the object or in the pattern of a discontinuity when present in the object.

(1) Note. The magnetization may be caused by direct electrical current, by alternating current, by alternating and direct current, or by a permanent magnet.

(2) Note. A discontinuity is a flaw which includes a crack, fault, or other defect that is present in a tested object that is capable of changing the magnetization pattern known to be formed from a perfect object.

SEE OR SEARCH THIS CLASS, SUBCLASS:

213,	for the detection of flaws by magnetizing a material with a magnetic recording medium thereon to record the field of the magnetized material.
215,	for particles with additives to enhance the viewing of magnetized particles.
217+,	for flaw detection of railroad rails.
452+,	for the use of particles to test flaws by electrostatic forces.

SEE OR SEARCH CLASS:

73,	Measuring and Testing, subclasses 632+ for flaw detection by means of compressional waves.
250,	Radiant Energy, subclass 358.1 for pipe inspection by invisible radiant energy, and for tire inspection by invisible radiation, subclasses 559.45+ for the photoelectric sensing of web, strand, or sheet material for defects by visible light.
356,	Optics: Measuring and Testing, particularly subclasses 430+ for flaw detection in webs; and subclasses 237.1+ for flaw testing generally.
374,	Thermal Measuring and Testing, subclasses 4+ for flaw detection by a thermal determination.
378,	X-Ray or Gamma Ray Systems or Devices, subclasses 58+ for X-ray flaw analysis.

[List of Patents for class 324 subclass 217]

217

Railroad rail flaw testing:

This subclass is indented under subclass 200. Subject matter which includes means to magnetize a railroad rail to create a test magnetic field in the rail, the apparatus to sense and indicate the sensing of the magnetic field being responsive to the field of the rail to note any change in the indication from the normal known magnetic pattern of the magnetized rail.

(1) Note. The subcombinations of means to magnetize a rail and of means to sense the magnetization of the rail are classified here.

SEE OR SEARCH THIS CLASS, SUBCLASS:

62+,	for the resistance testing of rails.
65,	particularly for the flaw testing of rails by resistance means.

SEE OR SEARCH CLASS:

73,	Measuring and Testing, subclasses 636+ for the testing of rails for flaws by vibration.
346,	Recorders, subclass 33 for a marking device which is responsive to a magnetic rail flaw detection device.

218	Rail joint cutout:
	This subclass is indented under subclass 217. Subject matter wherein the tested rail has ends and is joined to other rails by connectors forming joints between the rails, and includes means to prevent the sensing and indicating of the magnetic field of the joints by the apparatus to sense and indicate the sensing of the magnetic field of the rail.

219	Magnetic sensor within material:
	This subclass is indented under subclass 200. Subject matter wherein the apparatus to sense a magnetic field includes a sensor placed within tested material which has magnetic field associated with it, the apparatus to indicate the sensing of a magnetic field being responsive to the magnetic field of the material sensed by the sensor.

[List of Patents for class 324 subclass 220]

220

Sensor supported, positioned, or moved within pipe:

This subclass is indented under subclass 219. Subject matter wherein the material tested is a tube and the sensor has (1) means to transport the sensor through the tube, or (2) a support to position or hold the sensor within the tube.

(1) Note. The subcombination of a magnetic sensor and a support to hold, position, or move the sensor within a pipe is here.

(2) Note. An indicator of the distance traveled by the magnetic sensor in the pipe may be additionally claimed.

SEE OR SEARCH THIS CLASS, SUBCLASS:

260,	for magnetic sensors with a support generally.
262,	for magnetic sensor supports, per se.

SEE OR SEARCH CLASS:

33,	Geometrical Instruments, subclass 700 for bore extensometers, subclasses 772+ for rolling contact-type tube interior gauges, subclasses 792+ for internal dial gauges, and subclasses 814+ for screw adjustment type inside or inside-outside gauges.
250,	Radiant Energy, subclass 358.1 for pipe inspection by radiant energy examination.
378,	X-Ray or Gamma Ray System or Devices, subclasses 59+ for X-ray pipe testing.

[List of Patents for class 324 subclass 221]

221

Borehole pipe testing:

This subclass is indented under subclass 220. Subject matter wherein the tested pipe is a casing or a borehole in the earth.

SEE OR SEARCH THIS CLASS, SUBCLASS:

345,	for geological and subsurface testing for materials by a magnetic test.

SEE OR SEARCH CLASS:

33,	Geometrical Instruments, subclasses 302+ for borehole interior study processes, and subclasses 304+ for borehole direction or inclination meters.
73,	Measuring and Testing, subclasses 152.01+ for borehole and drilling study apparatus.
166,	Wells, subclass 64 for time or distance measuring, subclass 65.1 for electrical means combined with a well, and subclasses 250.01+ for processes involving indicating, testing, measuring, or locating within a well.
175,	Boring or Penetrating the Earth, subclass 4.51 for boring or penetrating with orienting or indicting.
250,	Radiant Energy, subclasses 253+ for geological testing or irradiating with radiant energy.
361,	Electricity: Electrical Systems and Devices, subclasses 248+ for igniting systems for explosive devices within a well bore.
367,	Communications, Electrical: Acoustic Wave System and Devices, subclasses 14+ for compressional wave geophysical systems, and subclass 86 for well bore electrical communications.
436,	Chemistry: Analytical and Immunological Testing, subclasses 25+ for geochemical exploration.

[List of Patents for class 324 subclass 222]

222

Hysteresis or eddy current loss testing:

This subclass is indented under subclass 200. Subject matter wherein the apparatus to sense and indicate the sensing of a magnetic field includes apparatus to measure the loss of energy of a cyclically varying magnetic field resulting from it passage through a magnetic material or through a material in which eddy currents are induced by the varying magnetic field.

SEE OR SEARCH THIS CLASS, SUBCLASS:

57,	for mutual inductance tests to determine inductance which cause eddy currents.
113,	for recording the result of an electrical measurement.
121,	for a cathode-ray tube indication of an electrical measurement.
142,	for the measurement of electrical real power.
451,	for power loss testing of magnetic material by causing heat by passing cyclic current through the material and measuring the power which causes the heat.

[List of Patents for class 324 subclass 223]

223

Hysteresis loop curve display or recording:

This subclass is indented under subclass 200. Subject matter wherein the apparatus to sense and indicate the sensing of a magnetic field is responsive to a material magnetized by a changing magnetic field going from a minimum to a maximum in one direction and than going from a minimum to a maximum in the opposite direction and produces a signal applied to a visual display or recorder which is the magnetization curve of the material.

SEE OR SEARCH CLASS:

313,	Electrical Lamp and Discharge Devices, subclasses 1+ for cathode-ray tube circuits of general application, and subclasses 364+ for deflection circuits for a cathode-ray tube.
346,	Recorders, subclasses 33+ for recorders combined with external recorder operating means.
347,	Incremental Printing of Symbolic Information, subclasses 226+ for recorders operated by a light beam including a cathode ray beam.

[List of Patents for class 324 subclass 224]

224

With temperature control of material or element of test circuit:

This subclass is indented under subclass 200. Subject matter wherein the apparatus to sense and indicate the sensing of a magnetic field is also responsive to magnetic fields modified by tested materials placed in a magnetic field and includes means to control the temperature of the material tested or some element of the apparatus to sense and indicate the sensing of the magnetic field.

(1) Note. The means to control the temperature includes heating and cooling.

SEE OR SEARCH THIS CLASS, SUBCLASS:

248,	for superconductive magnetometers which require low temperatures to function.

SEE OR SEARCH CLASS:

62,	Refrigeration, appropriate subclasses for devices to cool.
73,	Measuring and Testing, subclasses 15+ for thermal tests, and subclasses 339+ for temperature measuring means, per se.
148,	Metal Treatment, subclass 121 for the heat treatment of magnetic materials to intentionally change the magnetic properties, and subclass 509 for heat treatment of solid or semi-solid metal to modify or maintain the internal physical structure (i.e., microstructure) or chemical property of metal combined with the measuring, sensing, or testing of magnetic properties.
165,	Heat Exchange, particularly subclass 58 for heating and cooling.
219,	Electric Heating, subclasses 50+ for metal heating, and subclass 200 for heating devices for nonmetals.
361,	Electricity: Electrical Systems and Devices, subclass 140 for thermal change compensation for electromagnetic device control circuits, and subclass 141 for superconductivity electromagnetic device control circuits.
432,	Heating, appropriate subclass for the heating of materials nonelectrically.

[List of Patents for class 324 subclass 225]

225

With compensation for test variable:

This subclass is indented under subclass 200. Subject matter wherein the apparatus to sense and indicate the sensing of the magnetic field includes structure to correct for some condition which affects the test.

(1) Note. The magnetic field tested may be a magnetic field, per se, or a magnetic field modified by a material under test.

(2) Note. The condition may be magnetic interference, the spacing of the material tested with respect to the magnetic sensing means, or some condition of the apparatus to sense and indicate.

SEE OR SEARCH THIS CLASS, SUBCLASS:

224,	for temperature control of the tested material or an element of the test circuit.
244,	for magnetometers having disturbing magnetic field compensation.

[List of Patents for class 324 subclass 226]

226

Combined:

This subclass is indented under subclass 200. Subject matter wherein the apparatus to sense and indicate the sensing of a magnetic field is combined with the subject matter of another class when not provided for elsewhere.

(1) Note. The examination of material by magnetic fields and the testing of magnetic fields are here when combined with other subject matter.

(2) Note. In combination with magnetic testing are: demagnetizing, the conveying of material to or from the test, or the conveying of the magnetic test apparatus, diverse test apparatus of other classes and subject matter of other classes.

SEE OR SEARCH THIS CLASS, SUBCLASS:

157,	for measuring or sensing electricity combined with other subject matter.

SEE OR SEARCH CLASS:

194,	Check-Actuated Control Mechanisms, subclasses 320+ for material testers which use magnets.
209,	Classifying, Separating, and Assorting Solids, subclasses 38+ for the separation of solids from solids by magnetizing means and other separation means, subclasses 567+, 609, and 636 for article separating means involving magnetism, and subclasses 212+ for the separation of magnetic material from other material which is nonmagnetic or less magnetic.
356,	Optics: Measuring and Testing, subclass 72 for the combination of an optical test with other subject matter.

[List of Patents for class 324 subclass 227]

227

Plural tests:

This subclass is indented under subclass 200. Subject matter wherein (1) two or more variable magnetic parameters are separately sensed and indicated, at least one of which is sensed and indicated by apparatus to sense and indicate the sensing of a magnetic field, or (2) at least one of two or more separate tests is a magnetic test.

(1) Note. The separate tests may be performed sequentially or simultaneously.

(2) Note. A. Subject matter of this subclass includes, for example, permeameters wherein a sensed voltage is used to indicate a change in flux for a given value of magnetomotive force indicated by the current causing the force. B. Subject matter of this subclass includes, for example, (1) a nonmagnetic hardness test combined with a magnetic flaw test, or (2) two simultaneous but spatially separated magnetic flaw tests.

SEE OR SEARCH THIS CLASS, SUBCLASS:

403+,

for lamp and discharge device tests involving plural diverse characteristics or conditions.

228	With means to create magnetic field to test material:
	This subclass is indented under subclass 200. Subject matter which includes structure to form a magnetic field for testing material, the apparatus to sense and indicate the sensing of the magnetic field being responsive to the field as modified by the material tested.

[List of Patents for class 324 subclass 229]

229

Thickness measuring:

This subclass is indented under subclass 228. Subject matter wherein the material tested has two different surfaces, and the distance between the surfaces is measured by placing the two surfaces in the magnetic field and the apparatus to sense and indicate the sensing of the field is responsive to the field as modified by the material between the two surfaces to thus sense and indicate the distance between the surfaces.

(1) Note. Class 324 measures thickness by sensing a change in magnetic property of magnetic test. For measuring thickness by having contacts touching the tested material, see the Search Note below.

SEE OR SEARCH CLASS:

33,	Geometrical Instruments, measures thickness by having contacts touching the tested material; see subclasses 783+ for distance measuring devices, particularly subclass 835 for coating thickness measurement, and subclasses 174+ for gauges.
73,	Measuring and Testing, subclass 37.5 for the measurement of a dimension of a material by fluid means.
250,	Radiant Energy, appropriate subclasses for the measurement of a dimension of a material by invisible radiation.
356,	Optics: Measuring and Testing, subclass 629 for determining the thickness of light permeable material.
374,	Thermal Measuring and Testing, subclass 7 for a thickness determination by a thermal test.
378,	X-Ray or Gamma Ray Systems or Devices, subclasses 50 , 54+, and 89+ for X-ray thickness measuring.

230	Layer of layered material:
	This subclass is indented under subclass 229. Subject matter wherein the material tested is composed of dissimilar layered material and the thickness of one layer is found by placing the layered material in the magnetic field and the apparatus to sense and indicate the sensing of the magnetic field is responsive to the magnetic field modified by the layer to thus sense and indicate the depth of the layer.

[List of Patents for class 324 subclass 231]

231

With backing member:

This subclass is indented under subclass 229. Subject matter which includes a part next to one surface of the material and the apparatus to sense and indicate the sensing of the magnetic field next to the other surface opposite to the part; the part and the apparatus cooperating with each other to place tested material in the same relation each time with respect to the magnetic field and the apparatus to sense and indicate the sensing of the field.

(1) Note. The part generally but not always is part of the magnetic test circuit.

[List of Patents for class 324 subclass 232]

232

Plural magnetic fields in material:

This subclass is indented under subclass 228. Subject matter which includes means to create two or more magnetic fields in the tested material, the apparatus to sense and indicate the sensing of the magnetic field being responsive to the fields modified by the material to indicate some characteristic of the material.

(1) Note. Included are diverse magnetic fields at the same location in the material, or magnetic fields at different locations in the material, but not two fields of the same type aiding each other at the same place in the material.

[List of Patents for class 324 subclass 233]

233

With phase sensitive element:

This subclass is indented under subclass 228. Subject matter wherein the apparatus to sense and indicate the sensing of the magnetic field modified by the material tested includes an element which compares the electrical phase of the signal as received by the apparatus with the phase of the magnetic field used in the test, the difference in phase being used by the apparatus to show some characteristic of the tested material.

(1) Note. Here are mostly eddy current tests which do not fall out in the preceding subclasses. Eddy current tests not classified here will be found in the subclasses following when no phase detection is claimed.

[List of Patents for class 324 subclass 234]

234

Electrically energized nonforce type sensor:

This subclass is indented under subclass 228. Subject matter wherein the apparatus to sense and indicate the sensing of the magnetic field modified by the material includes a sensor which requires an electrical current to pass therethrough, and which senses and indicates the magnetic field other than by a force measurement.

(1) Note. Included are self-inductance-type field sensors.

SEE OR SEARCH THIS CLASS, SUBCLASS:

228,	for the testing of material magnetically by torque magnetometers and electrically energized sensors of force.
244,	for magnetometers.
260,	for magnetic sensors not electrically energized.
300+,	for the testing of material by nuclear or electronic induction.
323+,	for the magnetic testing of material by a magnetic field.
332+,	especially, which requires a magnetic field to test material within or part of the upper natural surface of the earth.

[List of Patents for class 324 subclass 235]

235

Noncoil type:

This subclass is indented under subclass 234. Subject matter wherein the energized sensor does not rely solely on inductive effects.

(1) Note. Here are sensors of the magnetoresistive and galvanomagnetic type which includes Hall effect sensors.

SEE OR SEARCH THIS CLASS, SUBCLASS:

251,	for Hall plate magnetometers.
252,	for magnetoresistive and semiconductor solid-state magnetometers.

SEE OR SEARCH CLASS:

338,	Electrical Resistors, subclass 32 for magnetoresistive and for Hall effect devices, per se.

[List of Patents for class 324 subclass 236]

236

Oscillator type:

This subclass is indented under subclass 234. Subject matter wherein the sensor is part of a frequency generator whereby the material-modified magnetic field is sensed by the sensor to control the frequency or the amplitude of the electrical wave generated by the frequency generator.

SEE OR SEARCH THIS CLASS, SUBCLASS:

234,	for sensing material-modified magnetic fields by self-inductive type sensors.

SEE OR SEARCH CLASS:

331,	Oscillators, subclass 65 for oscillators with a device responsive to an external physical condition. See subclass 64 of Class 331 for the line between Classes 331 and 324.

237	Material flaw testing:
	This subclass is indented under subclass 236. Subject matter wherein the material is magnetically tested for defects in the material.

[List of Patents for class 324 subclass 238]

238

Material flaw testing:

This subclass is indented under subclass 234. Subject matter wherein the material is magnetically tested for defects in the material.

(1) Note. A defect is any blemish, crack, or other inherent imperfection in a material that weakens the material.

SEE OR SEARCH THIS CLASS, SUBCLASS:

213,	for magnetic recording mediums attached to a tested magnetized material to record the material field.
216,	for flaw testing of magnetized material with magnetic particles.
217+,	for railroad flaw testing.
219+,	for flaw testing when the sensor is within the material.
237,	for flaw testers of the oscillator type.

[List of Patents for class 324 subclass 239]

239

Induced voltage-type sensor:

This subclass is indented under subclass 228. Subject matter wherein a voltage is induced in an electrical coil as a result of the change in the magnetic test field caused by the material tested.

SEE OR SEARCH THIS CLASS, SUBCLASS:

219+,	for testing material by placing a magnetic sensor within the material tested.
233,	for the testing of material by a test device which compares the phase of a test magnetic field with the phase of the signal sensed by the magnetic sensor.
254,	for fixed coil magnetometers responsive to a changing magnetic field.
257,	for moving coil magnetometers.
260+,	for magnetic field detection device sensors of the induced voltage type.

SEE OR SEARCH CLASS:

323,	Electricity: Power Supply or Regulation Systems, subclass 355 for transformers to deliver power to a single load.
336,	Inductor Devices, particularly subclass 221 for coil and core, and subclasses 222+ and 225+ for electrical windings, per se, which introduce electrical inductance into an electrical circuit.

[List of Patents for class 324 subclass 240]

240

Material flaw testing:

This subclass is indented under subclass 239. Subject matter wherein the material is magnetically tested for defects in the material.

SEE OR SEARCH THIS CLASS, SUBCLASS:

217+,	for rail flaw testing.
219+,	for magnetic flaw sensors placed within material tested magnetically.
260+,	for magnetic field dated on devices generally including those of the induced voltage type.

241	Opposed induced voltage sensors:
	This subclass is indented under subclass 240. Subject matter wherein there are two or more magnetic coil sensors of the magnetic field modified by the test material, the apparatus to indicate the sensing of the field modified by the test material being connected to two or more of the sensors to indicate the difference in the voltages induced in the sensors.

242	Plural sensors:
	This subclass is indented under subclass 240. Subject matter wherein there are two or more magnetic coil sensors of the magnetic field modified by the test material, the apparatus to indicate the sensing of the field modified by the test material being connected to two or more of the sensors to indicate the combined sensing of the material-modified field.

243	Plural sensors:
	This subclass is indented under subclass 239. Subject matter wherein there are two or more coil sensors of the induced voltage type, the apparatus to indicate the sensing of the magnetic field being connected to two or more of the sensors to note the combined sensing of material-modified magnetic field.

[List of Patents for class 324 subclass 244]

244

Magnetometers:

This subclass is indented under subclass 200. Subject matter wherein the apparatus to sense and indicate the sensing of a magnetic field is responsive to the intensity of the sensed magnetic field or the direction of the sensed magnetic field.

(1) Note. Subject matter classifiable in this subclass includes subcombinations or perfecting features peculiar to magnetometers and not classifiable elsewhere such as field compensating means for magnetometers.

SEE OR SEARCH THIS CLASS, SUBCLASS:

227,	plural magnetic tests of a magnetic field.
228+,	for the testing of material by magnetic fields which use magnetometers for the defection of the material-modified magnetic field.

SEE OR SEARCH CLASS:

33,	Geometrical Instruments, subclasses 300+ for compasses, particularly subclasses 356+ for magnetic field responsive error compensation.
174,	Electricity: Conductors and Insulators, subclasses 32 through 397for anti-inductive structures, particularly subclass 352 for shielded coils.
307,	Electrical Transmission or Interconnection Systems, subclass 89 for systems to prevent induction having means to control a magnetic field, and subclass 101 for residual or remnant magnetism control.
361,	Electricity: Electrical Systems and Devices, subclass 93.6 for abnormal current condition protection including transformer sensor.

244.1

Optical:

This subclass is indented under subclass 244. Subject matter wherein the apparatus or method for sensing and indicating a magnetic field includes a medium which responds to the magnetic field by altering the propagation (e.g., path, passage, etc.) or a property (e.g., polarization) of radiant light energy therethrough, where the output of the medium is representative of the magnetic field measured.

(1) Note. This subclass includes physical changes of the light path affecting the light.

SEE OR SEARCH THIS CLASS, SUBCLASS:

96+,	for devices which measure electricity using radiant energy.

SEE OR SEARCH CLASS:

250,	Radiant Energy, subclasses 200+ for photocells, circuits, and apparatus.
356,	Optics: Measuring and Testing, subclass 450 for optical testing by light wave interference.
359,	Optics: Systems (Including Communication) and Elements, subclasses 280+ for changing a bulk optical parameter by an applied magnetic field.
385,	Optical Waveguides, subclasses 12+ for environmentally sensing optical waveguides.

245	Plural sensor axis misalignment correction:
	This subclass is indented under subclass 244. Subject matter wherein the apparatus to sense and indicate the sensing of the magnetic field includes plural magnetic field sensors aligned with each other, the sensors when not aligned with each other producing errors in the magnetic field measurement, and means responsive to the sensing of the magnetic field by both sensors to adjust for the misalignment of the sensors, the apparatus to indicate being connected to the sensors.

[List of Patents for class 324 subclass 246]

246

With means to align field sensor with magnetic field sensed:

This subclass is indented under subclass 244. Subject matter wherein the apparatus to sense and indicate the sensing of the magnetic field includes a movable magnetic field sensor of the tested magnetic field and apparatus responsive to the magnetic field connected to the magnetic sensor responsive to the magnetic field to physically move the sensor to a predetermined position with respect to the sensed magnetic field.

SEE OR SEARCH CLASS:

318,	Electricity: Motive Power Systems, subclass 647 for electric servo motors under the control of magnetic field sensing sensors.

[List of Patents for class 324 subclass 247]

247

Nonparallel plural magnetic sensors:

This subclass is indented under subclass 244. Subject matter wherein the apparatus to sense the magnetic field includes several magnetic sensors positioned angularly with respect to each other so that an axis of another sensor will intersect the other axis and the apparatus to indicate is connected to the several sensors to note the combined sensing of the tested magnetic field.

SEE OR SEARCH THIS CLASS, SUBCLASS:

227,	for plural magnetic tests each having a magnetic field sensor.
228,	for magnetic tests to subject material to a magnetic field.
242,	particularly for material flaw testing apparatus using plural magnetic coil sensors.
243,	for material tests using plural magnetic coil sensors to examine material.

SEE OR SEARCH CLASS:

33,	Geometrical Instruments, subclass 300 for indicator of direction of force traversing material media apparatus including direction or inclination instruments, gyromagnetic compasses and magnetic field responsive instruments.
340,	Communications: Electrical, subclass 870.33 for continuously variable indicating apparatus having indication transmitters of the magnetic flux sensor type combined with circuitry connected to the transmitters, and subclass 345 for code transmitters which include magnetic flux sensing devices, per se.

[List of Patents for class 324 subclass 248]

248

Superconductive magnetometers:

This subclass is indented under subclass 244. Subject matter wherein the apparatus to sense and indicate the sensing of a magnetic field includes a sensor of the magnetic field or a magnetic shield for the apparatus to sense a magnetic field made of a material which has nearly zero resistance in one state and appreciable resistance in a second state.

(1) Note. Superconductivity is a property possessed by some metals, alloys, or compounds whereby the electrical resistance of the metals, alloys, or compounds decreases until a critical temperature is reached and the resistance becomes practically zero when the temperature of the metal, alloy, or compound is reduced to within a few degrees of absolute zero.

(2) Note. The apparatus to produce the low temperatures in the superconductors in order to permit the superconductors to function as a shield or a magnetic field sensor is not always claimed.

SEE OR SEARCH CLASS:

29,	Metal Working, subclass 599 for processes of manufacturing superconductor electrical devices.
323,	Electricity: Power Supply or Regulation Systems, subclass 44 for transformer systems using superconductors.
327,	Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 527+ for miscellaneous superconductive circuits.
331,	Oscillators, subclass 107 for superconductive oscillators using a superconductive active element.
335,	Electricity: Magnetically Operated Switches, Magnets, and Electromagnets, subclass 216 for superconductive magnets and electromagnets.
338,	Electrical Resistors, subclass 32 for superconductive resistors, per se.
365,	Static Information Storage and Retrieval, subclasses 160+ for superconductive magnetic storage systems.
377,	Electrical Pulse Counters, Pulse Dividers, or Shift Registers: Circuits and Systems, subclass 93 for electrically operated registers using superconductors.

[List of Patents for class 324 subclass 249]

249

Thin film magnetometers:

This subclass is indented under subclass 244. Subject matter wherein the apparatus to sense a magnetic field includes a thin single domain ferromagnetic film magnetized in a predetermined direction known as the easy axis of the film, the magnetization of the film upon placement in an external magnetic field to be tested assumes a different direction which is the resultant field vector of the film"s easy axis and the tested field axis, means to cyclically change the resultant magnetic field axis of the film, sensing means to note the cyclical changes in the magnetic field of the film caused by the shift of the resultant magnetic field due to the means to cyclically change the resultant magnetic field axis, and the apparatus to indicate being connected to the sensing means to note the result of the cyclical changes in the film.

(1) Note. A thin film is defined as a ferromagnetic element formed so as to have its magnetic domains aligned in a predetermined direction. This is usually done by vapor depositing the film in a magnetic field. In the absence of an external field the magnetization vector or magnetic moment will be aligned with the preferred "easy axis" of magnetization of the film. The "hard axis" of the magnetization of the film is in an orthogonal direction to the "easy axis". A thin magnetic film so formed has uniaxial anisotropy.

SEE OR SEARCH THIS CLASS, SUBCLASS:

227,	for plural separate magnetic tests.
228+,	for means to create a magnetic test field and a magnetic sensor to sense the test field.

SEE OR SEARCH CLASS:

257,	Active Solid-State Devices (e.g., Transistors, Solid-State Diodes), appropriate subclasses, including subclasses 108 , 414, and 421-427, for devices responsive to magnetic field.
307,	Electrical Transmission or Interconnection Systems, subclass 403 for nonlinear reactor systems having thin film parametron.
327,	Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclass 567 for miscellaneous thin film circuits.
365,	Static Information Storage and Retrieval, subclasses 171+ for thin film magnetic signal storage systems.
427,	Coating Processes, subclasses 547+ for pretreatment of a substrate or post-treatment of a coated substrate using magnetic field or force, 598+ to directly apply a coating using magnetic field or force.

[List of Patents for class 324 subclass 250]

250

Electronic tube or microwave magnetometers:

This subclass is indented under subclass 244. Subject matter wherein the apparatus to sense and indicate the sensing of a magnetic field includes (1) an ionizable gas tube magnetic field sensor having electrodes connected to appropriate voltages wherein the tested magnetic field causes the gas to ionize at different electrode voltages dependent upon the strength of the magnetic field, (2) an energized vacuum tube magnetic field sensor having a cathode ray beam and one or more electrodes or a fluorescent screen connected to appropriate voltages to attract the beam wherein the tested magnetic field acts to deflect the beam an amount dependent upon the strength of the tested field, or (3) an electrically conductive enclosure magnetic field sensor to which a signal is applied having a ferromagnetic material in the enclosure wherein the tested field affects the material to change the signal passed through the enclosure dependent upon the strength of the field.

(1) Note. The enclosure is a waveguide, resonant cavity, or a transmission line.

SEE OR SEARCH THIS CLASS, SUBCLASS:

58+,	for measuring microwave parameters or using microwave devices for determining nonelectric properties.

SEE OR SEARCH CLASS:

33,	Geometrical Instruments, subclass 360 for magnetic field direction indicating apparatus using cathode-ray tubes or photo-electric cells.
250,	Radiant Energy, subclass 298 for ionic separation or analysis apparatus using magnetic means to separate or deflections, and subclass 396 for apparatus to deflect or focus a charged particle beam.
313,	Electric Lamp and Discharge Devices, subclass 153 for electric lamp and discharge devices having a magnetic device, and subclass 364 for cathode-ray tubes, particularly subclass 421 for the beam deflection means of the cathode-ray tube.
315,	Electric Lamp and Discharge Devices: Systems, subclass 399 for cathode-ray tube beam deflection circuits.
333,	Wave Transmission Lines and Networks, subclasses 141+ for transmission line systems utilizing magnetic effects.

[List of Patents for class 324 subclass 251]

251

Hall plate magnetometers:

This subclass is indented under subclass 244. Subject matter wherein the apparatus to sense a magnetic field includes a thin sheet of conductive material whose thickness is small compared to a dimension of the sides of the sheet, electrical means connected at first diametrical points on the edge of the sheet to pass an electrical current through the sheet, electrical output means connected to second diametrical points on the edge of the sheet at right angles to the first diametrical points and the apparatus to indicate being connected to the electrical output means whereby the solid-state sheet when placed in a magnetic field to be measured normal to the first diametrical points will cause a voltage, consistent with the intensity of the tested magnetic field, at the second diametrical points, which voltage is sensed by the apparatus to indicate.

(1) Note. Compensation for misalignment of axis by means of potential balancing is here.

(2) Note. Hall plates may be made of germanium, bismuth, tellurium, copper, or indium antimonide.

SEE OR SEARCH THIS CLASS, SUBCLASS:

117,	for measuring electricity, per se, with a Hall effect device.
127,	for measuring current in a split core transformer with a Hall effect device.
207.2,	for magnetic displacement measurement wherein a sensor utilizes the Hall effect.

SEE OR SEARCH CLASS:

310,	Electrical Generator or Motor Structure, subclass 3 for Hall effect generators or converters.
323,	Electricity: Power Supply or Regulation Systems, subclass 368 for impedance systems including a Hall effect resistor.
327,	Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclass 511 for miscellaneous circuits having Hall effect devices sensitive to external magnetic effects.
329,	Demodulators, appropriate subclasses for magnetic demodulators which include Hall effect devices.
330,	Amplifiers, subclass 6 for amplifiers using the Hall effect.
332,	Modulators, subclass 172 for magnetic amplitude modulators using the Hall effect.
338,	Electrical Resistors, subclass 32 for Hall effect devices, per se.
365,	Static Information Storage and Retrieval, subclass 170 for Hall effect magnetic signal storage devices.

[List of Patents for class 324 subclass 252]

252

Semiconductor type solid-state or magneto-resistive magnetometers:

This subclass is indented under subclass 244. Subject matter wherein the apparatus to sense and indicate the sensing of a magnetic field includes (1) a resistance of magnetic material having a current flow there-through and an indicator connected to the resistance whereby the magnetic field tested passing through the material changes the current noted on the indicator, or (2) a sensor of semiconductor material having a current flow therethrough and an indicator connected to the sensor to note the change in current caused by the tested magnetic field acting on the sensor.

(1) Note. Subject matter of this subclass type includes, for example, p-n junction semi-conductor sensors wherein the current flow therethrough is used to indicate the magnetic field.

SEE OR SEARCH THIS CLASS, SUBCLASS:

207.21,	for magnetic displacement measurement wherein a sensor is magnetoresistive.
228,	for noncoil type magnetic sensors including transistors and other solid-state magnetic sensors responsive to a magnetic field modified by a tested material.

SEE OR SEARCH CLASS:

257,	Active Solid-State Devices (e.g., Transistors, Solid-State Diodes), appropriate subclasses, including subclasses 108 , 414, and 421-427, for devices responsive to magnetic field.
323,	Electricity: Power Supply or Regulation Systems, for circuits including active solid-state devices controlled by a magnetic field which controls the voltage or current in the circuits.
327,	Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 510+ for miscellaneous circuits and systems subjected to external magnetic effects.
330,	Amplifiers, subclass 62 for magneto-resistive-type amplifiers.
338,	Electrical Resistors, subclass 32 for magnetic field-type resistors.
360,	Dynamic Magnetic Information Storage or Retrieval, subclass 113 for information type magnetoresistive transducer structures.
361,	Electricity: Electrical Systems and Devices, subclass 235 for control circuits for electromagnetic devices having barrier layer devices controlled by a magnetic field.
365,	Static Information Storage and Retrieval, subclass 158 for magnetoresistive storage systems.

[List of Patents for class 324 subclass 253]

253

Saturable core magnetometers:

This subclass is indented under subclass 244. Subject matter wherein the apparatus to sense a magnetic field includes a ferromagnetic core having an alternating magnetic flux passing through the core, the magnetic field tested being concurrently passed through the core with the alternating flux and an electrical coil to sense the change in the magnetic flux caused by the magnetic field in the core, the apparatus to indicate being responsive to the electrical coil sensing the magnetic field change in the core.

SEE OR SEARCH THIS CLASS, SUBCLASS:

228,	for the magnetic testing of material.
236+,	particularly, which use coil-type magnetic field sensors.

SEE OR SEARCH CLASS:

33,	Geometrical Instruments, subclass 361 for flux gate sensors used in magnetic field responsive instruments indicating the direction of force traversing natural media.
318,	Electricity: Motive Power Systems, subclass 47 for magnetic field sensors that control an electric motor servo-system.
340,	Communications: Electrical, subclass 870.33 for continuously variable indicating apparatus having an inductor of the flux gate type.
341,	Coded Data Generation or Conversion, subclasses 20+ and 173+ for a code transmitter having a flux gate magnetic sensor.
360,	Dynamic Magnetic Information Storage or Retrieval, subclass 111 for flux gate magnetic sensing heads to sense or record information.
361,	Electricity: Electrical Systems and Devices, subclass 93.6 for abnormal current condition protection including transformer sensor, and subclasses 143+ for drive circuits for flux gate magnetic sensing devices which create the alternating flux for the sensing devices.

254	Second harmonic type:
	This subclass is indented under subclass 253. Subject matter wherein the electrical coil sensing the change in the magnetic field in the core is connected to the apparatus to indicate by means of a circuit which passes only a harmonic signal of the alternating magnetic flux impressed upon the core so that the apparatus to indicate the result of the sensing is responsive only to the harmonic signal passed by the circuit.

255	Peak voltage type:
	This subclass is indented under subclass 253. Subject matter wherein the composite alternating flux and the magnetic field tested produce a cyclically alternating magnetic flux in the core which will produce peak flux values each half cyclic of the alternating flux although the peaks are not symmetrical half waves of flux, and wherein electrical circuitry connected between the electrical sensing coil and the apparatus to indicate the sensing of the field determines the (1) peak value, (2) the difference in the peak value, or (3) the average value of the voltage induced in the sensing coil caused by the alternate half cycles of the flux in the core.

[List of Patents for class 324 subclass 256]

256

Energized movable sensing coil magnetometers:

This subclass is indented under subclass 244. Subject matter wherein the apparatus to sense a magnetic field is a movable electrically energized magnetic field sensing coil, the magnetic field created by the coil interacts with the magnetic field tested to produce a force which moves the sensing coil, and the apparatus to indicate the sensing of the field is connected to the coil to note the movement of the coil.

(1) Note. The magnetic field created in the sensing coil may be a steady state or a changing magnetic field.

(2) Note. The sensing coil may turn or be vibrated by the force caused by the interaction of the tested magnetic field with the field of the sensor.

SEE OR SEARCH THIS CLASS, SUBCLASS:

236,	for magnetic field sensors of the coil type which sense the change in a magnetic field caused by a tested material.
260,	for magnetic field sensors of the induction type not classified elsewhere.

[List of Patents for class 324 subclass 257]

257

Moving coil magnetometer:

This subclass is indented under subclass 244. Subject matter wherein the apparatus to sense a magnetic field is a movable magnetic field sensing coil placed within the field to be tested and has means to move the movable coil, and the apparatus to indicate the sensing of the magnetic field is connected to the sensing coil whereby the coil moving in the tested field has induced therein a voltage proportional to the number of turns of the coil and the time it takes for the moving coil to complete a cycle of movement.

(1) Note. The sensing coil may or may not have a ferromagnetic core.

(2) Note. The movement may be rotary, vibrator, or translatory.

(3) Note. A single conductor sensing a magnetic field connected to an indicator is included in the subject matter of this subclass type.

SEE OR SEARCH THIS CLASS, SUBCLASS:

323+,

for geophysical surface or subsurface exploration which may include a moving coil magnetometer to detect objects below the surface of the earth or material within the earth or a magnetic field within the earth.

SEE OR SEARCH CLASS:

33,	Geometrical Instruments, subclass 361 for indicators of direction of force traversing natural media which use a rotating or vibrating magnetic detector.
343,	Communications: Radio Wave Antennas, subclass 1 for radar devices which utilize a moving antenna, subclass 100 for directive radio systems that use a moving antenna, and subclass 757 for antennas with scanning, sweeping, or orienting means to move the antennas.

[List of Patents for class 324 subclass 258]

258

Fixed coil-magnetometer:

This subclass is indented under subclass 244. Subject matter wherein the apparatus to sense a magnetic field is a stationary electrical coil placed in a changing magnetic field to be tested, and the apparatus to indicate the sensing of the field is connected to the coil whereby the changing magnetic field induces in the coil a voltage proportional to the number of turns of the coil and the time it takes the changing field to make a complete change.

(1) Note. The tested changing field may be the movement of a magnetic core in the magnetic field tested, the magnetic core being moved relative to the sensing coil.

(2) Note. The sensing coil may include a ferromagnetic core.

[List of Patents for class 324 subclass 259]

259

Movable magnet or magnetic member interacts with magnetic field:

This subclass is indented under subclass 244. Subject matter with a movable permanent magnet acting as a magnetic field detector or a movable member of low magnetic reluctance acting as a magnetic field detector which includes material that can be temporarily magnetized by the tested field, the movable magnet"s magnetic field or the magnetic field of the temporarily magnetized material reacting to the tested magnetic field by moving until the force between the tested magnetic field and the movable magnet or the movable temporarily magnetized material is zero.

(1) Note. Magnetic polarity testers are here.

SEE OR SEARCH THIS CLASS, SUBCLASS:

205,	for permanent magnet testing.
225,	for test apparatus with compensation for a test variable.
256,	for magnetometers having a movable energized coil which reacts with a tested magnetic field to indicate the direction or strength of the tested field.

SEE OR SEARCH CLASS:

33,	Geometrical Instruments, subclass 310 for borehole movable magnetic indicators for direction or inclination, subclass 319 for gyroscopically mounted magnetic compasses, subclass 352 for magnetic compass type directional indicators, and subclasses 355+ for magnetic compasses.
73,	Measuring and Testing, subclasses 382+ for scales using permanent magnets to determine the force of gravity.
335,	Electricity: Magnetically Operated Switches, Magnets, and Electromagnets, subclasses 205+ for permanent magnet actuated switches, and subclasses 302+ for magnets, per se.

[List of Patents for class 324 subclass 260]

260

Magnetic field detection devices:

This subclass is indented under subclass 200. Subject matter which includes magnetic field sensing devices, per se, which are not classified elsewhere.

SEE OR SEARCH THIS CLASS, SUBCLASS:

213,	for a magnetic recording medium placed on a magnetized test material which assumes the magnetization of the material and requires iron particles to visibly see the pattern of recording medium.
214,	for paramagnetic particles placed in a tested magnetic field to note the pattern of the test field or on a magnetized test material to note the magnetization pattern of the magnetized material.
220+,	for magnetic field sensing device and a support for the device to hold, position, or move the device in a pipe or borehole.
226,	for apparatus involving a magnetic field detector combined with a diverse art device of another class.
228+,	for means to create a magnetic test field and a magnetic sensor of the test magnetic field.
244+,	for magnetometers which involve a magnetic sensor and an indicator responsive to the sensor.

SEE OR SEARCH CLASS:

29,	Metal Working, subclass 595 for indicating transducer making processes.
257,	Active Solid-State Devices (e.g., Transistors, Solid-State Diodes), appropriate subclasses, including subclasses 108 , 414, and 421-427, for devices responsive to magnetic field.
338,	Electrical Resistors, subclasses 32+ for magnetic field or compass resistive devices including those of the Hall and superconductive type.
343,	Communications: Radio Wave Antennas, subclasses 700+ for antennas.
360,	Dynamic Magnetic Information Storage or Retrieval, subclasses 110+ for magnetic transducers, per se, used in dynamic magnetic information systems.
361,	Electricity: Electrical Systems and Devices, subclasses 139+ , particularly subclasses 170+ for condition responsive control circuits for electromagnetic relay or solenoid devices, including subclasses 179+ for metal presence or absence devices.
365,	Static Information Storage and Retrieval, for static magnetic information devices and the storage elements, per se, especially subclass 157 for magnetostrictive; and subclass 160 for superconductive information storage devices.
367,	Communication, Electrical: Acoustic Wave Systems and Devices, subclasses 156 and 168 for underwater magnetostrictive transducers.

[List of Patents for class 324 subclass 261]

261

With support for article:

This subclass is indented under subclass 260. Subject matter wherein material is to be examined magnetically by a magnetic field sensing device and structure is provided to hold the material with respect to the sensor so that the sensing can be performed.

SEE OR SEARCH THIS CLASS, SUBCLASS:

226,	for testing material magneticallym and conveying the tested material to or from the test.
262,	for supports for magnetic sensing devices.
756.01	through 756.07 for support for device under test or test structure in electrical testing generally.

SEE OR SEARCH CLASS:

248,	Supports, subclasses 176+ for article stands, and subclasses 309+ for article brackets.
250,	Radiant Energy, subclass 491.1 for means to align or position an object relative to a detector.

[List of Patents for class 324 subclass 262]

262

Magnetic test structure elements:

This subclass is indented under subclass 200. Subject matter which includes supports for tested material and sensing devices, and other elements not provided for elsewhere.

SEE OR SEARCH THIS CLASS, SUBCLASS:

756.01

through 756.07 for support for device under test or test structure in electrical testing generally.

SEE OR SEARCH CLASS:

174,	Electricity: Conductors and Insulators, particularly subclasses 32+ for anti-inductive structures.
248,	Supports, for holding devices for materials, particularly subclasses 2+ for machinery supports.

[List of Patents for class 324 subclass 263]

263

Current through test material forms test magnetic field:

This subclass is indented under subclass 200. Subject matter which includes an electric circuit including terminals to contact a material to be magnetically tested so that current through the material and the terminals create a magnetic field in the material for test purposes.

(1) Note. Demagnetization as well as magnetization can be claimed as long as the test material forms the test field.

SEE OR SEARCH THIS CLASS, SUBCLASS:

217+,	for testing railroad rails by magnetizing the rail and sensing the magnetic field in the rail with or without an indication of the sensing.
228+,	for magnetically testing material.

SEE OR SEARCH CLASS:

335,	Electricity: Magnetically Operated Switches, Magnets, and Electromagnets, subclasses 209+ for magnets and electromagnets, and subclass 284 for magnetizing and demagnetizing magnets and electromagnets.
336,	Inductor Devices, subclasses 5+ for inductors, per se, which are impedance devices which produce a magnetic field when energized.
361,	Electricity: Electrical Systems and Devices, subclasses 143+ for systems for magnetizing, demagnetizing, or controlling the magnetic field, and subclass 267 for demagnetizing systems and processes.

[List of Patents for class 324 subclass 300]

300

PARTICLE PRECESSION RESONANCE:

This subclass is indented under the class definition. Subject matter relating to the measurement of the energy interchange between precessing atomic particles in a surrounding electromagnetic field.

(1) Note. The energy interchange may be characterized by a ratio between the mechanical angular momentum and the magnetic moment of an atomic system.

(2) Note. Precession is a change in the orientation of the axis of a rotating particle, the effect of which is to rotate this axis (axis of spin) about a line (axis of precession) perpendicular to its original direction and to the axis (axis of torque) of the moment producing the change.

(3) Note. Resonant frequency is the frequency at which a given system or object will respond with maximum amplitude when driven by an external sinusoidal force of constant amplitude.

[List of Patents for class 324 subclass 301]

301

Using magnetometer:

This subclass is indented under subclass 300. Subject matter utilizing means to measure the effects of external magnetic fields upon the resonance of a host material in a controlled electromagnetic field.

(1) Note. Host material is a material in which the resonance properties have been determined under controlled magnetic field conditions.

SEE OR SEARCH THIS CLASS, SUBCLASS:

244+,

for magnetometers, per se.

[List of Patents for class 324 subclass 302]

302

To determine direction:

This subclass is indented under subclass 301. Subject matter wherein the magnetometer is used to determine the direction of an external magnetic field relative to the location of the magnetometer.

(1) Note. External is used to mean those magnetic fields external of the instrument being used.

[List of Patents for class 324 subclass 303]

303

Using well logging device:

This subclass is indented under subclass 300. Subject matter in which earth subsurface materials are subjected to magnetic resonance measurement by using a well logging device to transport the components of the testing system to the location to be tested.

SEE OR SEARCH THIS CLASS, SUBCLASS:

346,	for systems using magnetic means to determine the electrical characteristics of the subsurface.

SEE OR SEARCH CLASS:

73,	Measuring and Testing, subclasses 152.02+ for a process or an apparatus for well logging, per se, wherein the process or the apparatus is not purely electrical or purely magnetic.

[List of Patents for class 324 subclass 304]

304

Using optical pumping or sensing device:

This subclass is indented under subclass 300. Subject matter in which a source of optical energy is applied to the sample and a resultant amount of optical energy is reradiated and sensed as a measure of a controlled interaction between the metastable state of an atomic system and a steady magnetic field.

(1) Note. Metastable is the marginal energy state of an electron above a reference ground within an atom, and having a definite lifetime.

305	Having particular optical cell structure:
	This subclass is indented under subclass 304. Subject matter wherein the optical cell is designed to aid the sensing of reradiated optical energy.

[List of Patents for class 324 subclass 306]

306

Determine fluid flow rate:

This subclass is indented under subclass 300. Subject matter in which a fluid is magnetically tagged as a net magnetization in a predetermined direction at a tagging station for detection at a known distance downstream at a detection station within a measured time interval.

(1) Note. Magnetically tagged refers to the magnetic resonance of a fluid volume upon passage through a magnetic induction coil.

SEE OR SEARCH CLASS:

73,	Measuring and Testing, subclass 861.11 for electromagnetic induction-type volume or rate of flow meters.
116,	Signals and Indicators, subclass 112 for fluid flow indicators.
600,	Surgery, particularly subclass 419 for magnetic resonance imaging or spectroscopy of fluid flow limited to medically evaluating a body liquid or gas traveling through a living body and where structure particularly adapted for placement on or in the body is claimed.

[List of Patents for class 324 subclass 307]

307

Using a nuclear resonance spectrometer system:

This subclass is indented under subclass 300. Subject matter in which a spectrometer is used to induce and measure resonance in the nucleus of an atom or group of atoms.

(1) Note. The spectrometer system would include at least a polarizing magnetic field element, a signal transmitter and receiver along with transducer coils coupled to a sample material being measured, and an indicator to readout information obtained.

SEE OR SEARCH CLASS:

600,	Surgery, particularly subclasses 410+ for a magnetic resonance imaging or spectroscopy device where structure particularly adapted for placement on or in a living body is claimed.
850,	Scanning-Probe Techniques or Apparatus; Applications of Scanning-Probe Techniques, e.g., Scanning-Probe Microscopy [SPM], subclasses 46 through 49for magnetic force microscopy.

308	Including a test sample and control sample:
	This subclass is indented under subclass 307. Subject matter in which the nuclear resonance measurement of an unknown material is made by comparison with the resonance of a known material.

309	To obtain localized resonance within a sample:
	This subclass is indented under subclass 307. Subject matter in which a measurement of nuclear magnetic resonance at controlled locations within a sample volume is obtained.

[List of Patents for class 324 subclass 310]

310

By scanning sample frequency spectrum:

This subclass is indented under subclass 307. Subject matter wherein the application of pulsed energy to an atom nucleus over a controlled range of frequencies results in relative energy absorption by the atom or atoms of a sample material at resonance.

(1) Note. Scanning may also take place as a result of an increase or decrease in magnetic field strength.

[List of Patents for class 324 subclass 311]

311

With signal decoupling:

This subclass is indented under subclass 307. Subject matter in which feedback from the signal receiver to the transmitter is suppressed or eliminated.

(1) Note. The receiver feedback is not restricted to signals from the receiving coil and electronic components, but also includes the received and reradiated energy of the resonant sample material.

[List of Patents for class 324 subclass 312]

312

By spectrum storage and analysis:

This subclass is indented under subclass 307. Subject matter wherein the nuclear resonant frequencies of the sample material are transformed to memory and recalled for computation.

(1) Note. Transformation may include the conversion of resonant frequency signal information from analog to digital form.

313	Including polarizing magnetic field/radio frequency tuning:
	This subclass is indented under subclass 307. Subject matter wherein the degree of resolution at resonance is a result of adjustment between magnetic field strength and the frequency at which magnetic resonance occurs.

[List of Patents for class 324 subclass 314]

314

With conditioning of transmitter signal:

This subclass is indented under subclass 307. Subject matter in which the signal information applied to the sample to induce resonance is made to conform with the predetermined frequency or phase conditions of a transmitter.

(1) Note. The subject matter under frequency or phase control of a transmitted signal would involve an improvement in sample resonance resolution, sensitivity, stability, or possibly the removal of unwanted sidebands from a frequency system.

315	With sample resonant frequency and temperature interdependence:
	This subclass is indented under subclass 307. Subject matter in which the nuclear resonance of the sample material is measured as a function of temperature, or the temperature of the sample material is measured as a function of nuclear resonance.

[List of Patents for class 324 subclass 316]

316

Using an electron resonance spectrometer system:

This subclass is indented under subclass 300. Subject matter in which a spectrometer is used to induce and measure electron resonance of a sample material.

(1) Note. The electrons of atoms of a sample material refers to the electrons of a single atom as well as electrons of bonded atoms.

(2) Note. A spectrometer system as used here would include at least a signal transmitter coupled to a microwave cavity in which a sample material is placed between the poles of a steady magnetic field and a receiver coupled to relay sample material resonance to an indicator.

317	Including a test sample and control sample:
	This subclass is indented under subclass 316. Subject matter wherein the electron resonance of an unknown material is made by comparison with the resonance of known material.

[List of Patents for class 324 subclass 318]

318

Spectrometer components:

This subclass is indented under subclass 300. Subject matter comprising structural components of a spectrometer.

SEE OR SEARCH CLASS:

600,	Surgery, particularly subclass 419 for a magnetic resonance imaging or spectroscopy system component where structure particularly adapted for contacting or conforming to a body part of a patient is claimed.

319	Polarizing field magnet:
	This subclass is indented under subclass 318. Subject matter comprising the details of polarizing field magnet structure designed specifically for use with a spectrometer.

320	With homogeneity control:
	This subclass is indented under subclass 319. Subject matter where magnetic circuit component design permits a uniform magnetic field gradient to be obtained.

321	Sample holder structure:
	This subclass is indented under subclass 318. Subject matter comprising sample holders to be used specifically with a spectrometer.

322	Electronic circuit elements:
	This subclass is indented under subclass 318. Subject matter comprising basic circuit elements which include active and passive devices designed specifically for use in a spectrometer system.

[List of Patents for class 324 subclass 323]

323

OF GEOPHYSICAL SURFACE OR SUBSURFACE IN SITU:

This subclass is indented under the class definition. Subject matter relating to the determination of an electrical characteristic of the subsurface of the earth in situ.

(1) Note. Subsurface is defined as including everything, whether composition, article, structure, or formation which lies below the upper natural surface of the earth. The upper surface is defined as being the uppermost nongaseous thing which lies on the earth, and may be mud, water, snow, leaves, dead trees, ice pavements, crops of buildings and such upper surface is defined as being natural if of the same type (e.g., leaves) which is found in nature, whether deposited by nature or not. Thus, under the subclass definition, the determination of geologic structure under building foundations or the location or treasure buried in the earth is included, but the location of treasure concealed in the building wall is not included.

(2) Note. The electrical characteristics which are determined may include streaming, telluric, terrestrial or self-potentials, resistance, dielectric constant, magnetic reluctance, inductance, conductance, capacitance, and magnetism.

SEE OR SEARCH THIS CLASS, SUBCLASS:

376,	for the analysis of core samples, not in situ in the earth, and other appropriate subclasses for the analysis of samples which are not in situ, or for the location of objects which are not below the natural surface of the earth. Note particularly subclasses 67, 158, and 200+.

SEE OR SEARCH CLASS:

23,	Chemistry: Physical Processes, subclass 230 for geochemical exploration.
73,	Measuring and Testing, subclasses 152.01+ for mechanical (e.g., thermal) analysis of bore holes.
166,	Wells, subclasses 250+ for well processes including indicating, testing, or measuring steps; subclass 64 for well apparatus including time or distance measuring, temperature responsive or counting means; and subclass 66 for well apparatus including electrical indicating means.
175,	Boring or Penetrating the Earth, subclass 40 and particularly subclass 50 for the combination of earth boring with electrical earth formation logging. The mere nominal recitation of a conventional earth boring step or means will not preclude classification in Class 324.
181,	Acoustics, subclass .5 for nonelectrical geophysical exploration by the use of seismic waves. Also note the reference to Class 340 below.
250,	Radiant Energy, subclasses 253+ for geophysical exploration by the use of radiant energy of the invisible type, including electromagnetic waves above the microwave frequency band.
340,	Communications: Electrical, subclass 853.8 for a wellbore telemetering system.
343,	Communications: Radio Wave Antennas, subclasses 5+ for radar systems which are used in geophysical exploration, as for example, radar sets which are lowered down a bore hole to determine the size of the bore.
367,	Communications, Electrical: Acoustic Wave Systems and Devices, subclasses 14+ for seismic prospecting using electrical acoustic wave systems.

[List of Patents for class 324 subclass 324]

324

Including borehole fluid investigation:

This subclass is indented under subclass 323. Subject matter relating to the determination of an electrical property of the fluid in a well, borehole, or other opening in the earth.

(1) Note. The fluid may be oil, gas, water, brine, or any other fluid.

SEE OR SEARCH THIS CLASS, SUBCLASS:

438,	for determining the pH or conductivity of an electrolyte.

SEE OR SEARCH CLASS:

73,	Measuring and Testing, subclasses 152.18+ for fluid analysis in a borehole or drilling test wherein the analysis is not made by purely electrical or purely magnetic means.
204,	Chemistry: Electrical and Wave Energy, subclasses 400+ as the residual home for apparatus used for electrolytic analysis or testing, per se.
205,	Electrolysis: Processes, Compositions Used Therein, and Methods of Preparing the Compositions, subclasses 775+ as the residual home for a process of electrolytic analysis or testing, per se.
252,	Compositions, subclass 62.2 for electrolytes of general utility.

[List of Patents for class 324 subclass 325]

325

To determine fluid entry:

This subclass is indented under subclass 324. Subject matter relating to the determination of the subsurface location of the point or region of entry of a fluid into or out of a well, borehole, or other opening in the earth.

SEE OR SEARCH CLASS:

73,

Measuring and Testing, subclass 40.5 for the determination of the leakage or ingress of fluid from or into a conduit in situ and subclasses 152.18+ for a rate of fluid flow measuring or fluid analysis in a borehole or drilling test wherein the measurement or the analysis is not made by purely electrical means or purely magnetic means.

[List of Patents for class 324 subclass 326]

326

For small object detection or location:

This subclass is indented under subclass 323. Subject matter relating to the detection or location in the earth of items which are relatively small compared to the size of the geoligic formation in which they are found.

(1) Note. The items may be objects such as land mines, unexploded shells, lost or buried treasure, pipes, etc.

SEE OR SEARCH THIS CLASS, SUBCLASS:

67,	and 200+, for the detection of concealed objects, not below the natural surface of the earth, using magnetic or electromagnetic sensing, as the location of pipe in walls.

[List of Patents for class 324 subclass 327]

327

Using oscillator coupled search head:

This subclass is indented under subclass 326. Subject matter wherein one or more parameters of an oscillator, coupled to or formed in conjunction with a coil or antenna moved over the region of exploration, are monitored.

SEE OR SEARCH THIS CLASS, SUBCLASS:

332,	for subject matter under subclass 323 using a radiant energy transmitter.

SEE OR SEARCH CLASS:

331,	Oscillators, for a particular type of oscillator circuitry.

[List of Patents for class 324 subclass 328]

328

Of the beat frequency type:

This subclass is indented under subclass 327. Subject matter having means for mixing the search head signal with another signal to produce a difference frequency output.

SEE OR SEARCH CLASS:

331,	Oscillators, subclasses 37+ for beat frequency oscillator circuits in general.

[List of Patents for class 324 subclass 329]

329

Using movable transmitter and receiver:

This subclass is indented under subclass 326. Subject matter wherein an antenna or coil means for generating an electromagnetic field and a separate pickup coil or antenna means responsive to the electromagnetic field as modified by the object to be detected are transported simultaneously over the area of investigation.

SEE OR SEARCH THIS CLASS, SUBCLASS:

330,	for transmitters and receiver combinations used in aerial surveys.
334,	for transmitter-receiver systems for geophysical prospecting in general.

SEE OR SEARCH CLASS:

455,	Telecommunications, subclass 90.1 for portable transmitter-receiver systems having particular application.

[List of Patents for class 324 subclass 330]

330

By aerial survey:

This subclass is indented under subclass 323. Subject matter in which the determination of the electrical property is made by means which are situated by a substantial distance above the earth"s surface.

(1) Note. The means may, for example, be carried by a projectile, rocket, aircraft, balloon, or may be supported on towers. The transportation of such means in a mere surface vehicle, such as an automobile, is not considered to be within the scope of this subclass.

[List of Patents for class 324 subclass 331]

331

For magnetic field detection:

This subclass is indented under subclass 330. Subject matter having means for detecting a component of the earth"s magnetic field.

SEE OR SEARCH THIS CLASS, SUBCLASS:

345,	for magnetic prospecting means in general.

[List of Patents for class 324 subclass 332]

332

With radiant energy or nonconductive-type transmitter:

This subclass is indented under subclass 323. Subject matter having means for radiating electrostatic or electromagnetic energy into the earth and for measuring a circuit parameter of the radiating means.

(1) Note. The means for radiating the energy, for example, may be an oscillator search coil, and the reaction of the formation on the oscillator field, due to variable loading, may furnish the indication which is desired.

SEE OR SEARCH THIS CLASS, SUBCLASS:

327,	for the measurement of oscillator circuit parameters in small object detection.

[List of Patents for class 324 subclass 333]

333

This subclass is indented under subclass 332. Subject matter in which the transmitter is adapted for use within a drill hole in the earth.

SEE OR SEARCH THIS CLASS, SUBCLASS:

338,	for borehole investigation with separate pickup of radiated energy.
346,	for borehole investigation using magnetic means.
351,	355 and 366+, for electrode arrangements used in a borehole.

[List of Patents for class 324 subclass 334]

334

With separate pickup:

This subclass is indented under subclass 332. Subject matter having means distinct from the radiating means, for detecting the energy which has been radiated.

(1) Note. The earth, for example, may act as a mutual inductance to convey a variable amount of energy from a transmitter coil to a receiver coil, in dependence upon the electrical characteristics of the formation.

SEE OR SEARCH THIS CLASS, SUBCLASS:

329,	for the detection of small objects using transmitter-receiver means.
330,	for transmitter-receiver systems used in aerial surveys.

SEE OR SEARCH CLASS:

455,	Telecommunications, subclasses 39+ for particular transmitter-receiver systems used in communication.

[List of Patents for class 324 subclass 335]

335

Employing multiple frequencies:

This subclass is indented under subclass 334. Subject matter in which more than one frequency is employed for investigating the subsurface formation between the transmitter and pickup.

(1) Note. The plurality of frequencies may be produced by varying the frequency of the signal from a single source, or, by provision of a plurality of different frequency sources.

[List of Patents for class 324 subclass 336]

336

To detect transient signals:

This subclass is indented under subclass 334. Subject matter wherein the transmitter signal is such as to cause decaying secondary signals to emanate from subsurface ore bodies and mineral deposits and the pickup means detects such decaying secondary signals.

SEE OR SEARCH THIS CLASS, SUBCLASS:

360,	for electrode systems which detect transient-type signals.

[List of Patents for class 324 subclass 337]

337

To detect return wave signals:

This subclass is indented under subclass 334. Subject matter having the pickup means positioned at the same location as the transmitter for receiving reflections or reradiations of the transmitted signal.

SEE OR SEARCH CLASS:

343,	Communications: Radio Wave Antennas, subclasses 5+ for radar systems.

[List of Patents for class 324 subclass 338]

338

With radiant energy or nonconductive-type receiver:

This subclass is indented under subclass 334. Subject matter adapted for use within a drill hole in the earth.

SEE OR SEARCH THIS CLASS, SUBCLASS:

333,	for measuring parameters of a radiant energy means positioned in the borehole.
346,	for borehole investigation using magnetic means.
351+,	355 and 366+, for electrode arrangements used in a borehole.

[List of Patents for class 324 subclass 339]

339

By induction logging:

This subclass is indented under subclass 338. Subject matter in which eddy currents are induced in the formations surrounding the borehole by an alternating electromagnetic field from a transmitter coil and a secondary electromagnetic field set up by the eddy currents induces an electromotive force in the pickup or receiver coil.

SEE OR SEARCH THIS CLASS, SUBCLASS:

239+,

for induced voltage-type sensors in magnetic testing.

340	To measure susceptibility:
	This subclass is indented under subclass 339. Subject matter relating to the measurement of magnetic properties of the formation.

341	To measure dielectric constant:
	This subclass is indented under subclass 339. Subject matter relating to the measurement of permittivity properties of the formation.

342	Using a toroidal coil:
	This subclass is indented under subclass 339. Subject matter in which one or both of the transmitter and pickup coils are in the configuration of a toroid.

343	Using angularly spaced coils:
	This subclass is indented under subclass 339. Subject matter in which the axis of one or more of the transmitter coils is nonparallel to the axis of one or more of the receiver coils.

[List of Patents for class 324 subclass 344]

344

This subclass is indented under subclass 323. Subject matter having means for receiving electrostatic or electromagnetic energy from above or below the surface of the earth.

(1) Note. The means, for example, may be responsive to radiant energy produced by natural sources but not by artificial sources. Receivers responsive to energy produced by an artificial source are classifiable elsewhere.

SEE OR SEARCH THIS CLASS, SUBCLASS:

332+,	for this subject matter having transmitter means to radiate electrostatic or electromagnetic energy into the earth.
334,	for receivers responsive to energy produced by an artificial source.
359,	for a radiant energy pickup means responsive to radiant energy produced by artificial earth currents.

[List of Patents for class 324 subclass 345]

345

By magnetic means:

This subclass is indented under subclass 323. Subject matter having magnetic means to determine the electrical characteristics of the subsurface.

(1) Note. For example, the magnetic field, due to artificial or natural earth current, may be determined.

SEE OR SEARCH THIS CLASS, SUBCLASS:

331,	for determining the magnetic field by aerial survey.

[List of Patents for class 324 subclass 346]

346

Using electrode arrays, circuits, structure, or supports:

This subclass is indented under subclass 345. Subject matter adapted for use within a drill hole in the earth.

SEE OR SEARCH THIS CLASS, SUBCLASS:

303,	for magnetic resonance measuring using well logging systems.
333,	for measuring parameters of a radiant energy means positioned in the borehole.
338,	for borehole investigation with separate pickup of radiant energy.
351,	355 and 366+, for electrode arrangements used in a borehole.

[List of Patents for class 324 subclass 347]

347

This subclass is indented under subclass 323. Subject matter relating to means for introducing electric currents into the subsurface or for collecting electric currents from the subsurface by conduction.

(1) Note. This subclass includes the structure or configuration of one or more electrodes and the means for supporting such electrodes. The electrodes and their supports are primarily of the borehole type, although not limited thereto.

SEE OR SEARCH THIS CLASS, SUBCLASS:

437,	445 through 449, for electrode structures and systems.

SEE OR SEARCH CLASS:

128,	Surgery, subclasses 2.06 and 2.1 for the structure of electrodes utilized in medical diagnosis, such as gelatin electrodes.

[List of Patents for class 324 subclass 348]

348

For detecting naturally occurring fields, currents, or potentials:

This subclass is indented under subclass 347. Subject matter for measuring a field, current, or potential which exists as a result of the inherent nature of the subsurface formations and not arising by virtue of an artificial current source.

(1) Note. For purposes of this subclass naturally occurring fields, currents, or potentials are considered to include those resulting from such sources as electric powerlines, electrical machinery, and underground pipes. These sources are considered a permanent part of the environment.

SEE OR SEARCH THIS CLASS, SUBCLASS:

72,	for detecting potentials in a specific environment.

349	Of the telluric type:
	This subclass is indented under subclass 348. Subject matter wherein the potentials or fields are associated with naturally occurring variable current which permanently circulate in vast sheets within the outermost layer of the earth"s crust.

350	Including magneto-telluric type:
	This subclass is indented under subclass 349. Subject matter for carrying out the telluric measurements in conjunction with measurements of the earth"s magnetic field.

[List of Patents for class 324 subclass 351]

351

Combined with artificial source measurement:

This subclass is indented under subclass 348. Subject matter adapted for use within a hole which has been drilled or is being drilled within the earth.

SEE OR SEARCH THIS CLASS, SUBCLASS:

333,	for measuring parameters of a radiant energy means positioned in the borehole.
338+,	for borehole investigation with separate pickup of radiated energy.
346,	for borehole investigation using magnetic means.
355,	for borehole electrodes coupled to an artificial current source.
366+,	for separate pickup electrodes.

[List of Patents for class 324 subclass 352]

352

This subclass is indented under subclass 351. Subject matter including one or more additional types of electrode measurements employing a source of electrical energy other than a natural source.

(1) Note. The "additional" types of measurements include only those which would be classified within this class (324).

353	With fluid movement or pressure variation:
	This subclass is indented under subclass 351. Subject matter including means for causing the movement of the fluid or variations in the pressure of the fluid existing within the borehole or the formations surrounding the borehole.

354	Coupled to artificial current source:
	This subclass is indented under subclass 347. Subject matter in which a parameter of the current introduced into the subsurface is measured.

[List of Patents for class 324 subclass 355]

355