Measuring electric variables or properties.

Measuring electric variables directly, e.g. electromechanical instruments (see Glossary of terms) where the measured electric variables directly effect the indication of the measured value.

Measuring electric variables by derivation from other electric variables, i.e. arrangements (see Glossary of terms) involving circuitry to obtain an indication of a measured value by deriving, calculating or otherwise processing electric variables, e.g. by comparison with another value.

Measuring or investigating electric properties of materials.

Electric testing of analogue or digital electric devices, apparatus or networks, or measuring their characteristics.

Indicating presence or sign of current or voltage.

The following technical subjects are therefore covered, the list being non-exhaustive:

Measuring time integral of electric power or current (i.e. Energy), e.g. Of consumption

Displaying electric variables or waveforms

Measuring currents or voltages or for indicating presence or sign thereof

Measuring electric power or power factor

Measuring time integral of electric power or current, e.g. By electronic methods

Measuring frequencies (of electric signals); measuring and analysing frequency spectra (of electric signals)

Measuring phase angle between a voltage and a current or between voltages or currents

Measuring resistance, reactance, impedance, or electric characteristics derived therefrom

Testing electric properties of apparatus, e.g. Discharge tubes, amplifiers, transistors, integrated circuits

Locating electric faults

Electrical testing characterised by what is being tested not provided for elsewhere

Testing for digital signal parameters (delay, skew, signal level) and characterization of device performance by use of test patterns; test apparatus or integrated test circuits therefor; methods for test pattern generation

Details, testing or calibrating of G01R related instruments or arrangements

Measuring magnetic variables or properties

Measuring magnetic variables.

Measuring or investigating magnetic properties of materials.

The following technical subjects are therefore covered, the list being non-exhaustive:

Measuring direction or amount of magnetic fields, or measuring characteristics of magnetic materials

Apparatus based on magnetic resonance, e.g. Nmr, mri, epr (i.e. Esr) (see synonyms and keywords) and not specially adapted for a particular application

Details, testing or calibrating of related instruments or arrangements

Investigating electric variables or properties

This subclass covers measuring or investigating electric properties of materials, whereas measuring or investigating non-electric or non-magnetic properties of materials by the use of electric means or based on electrical variables is covered by e.g. group G01N 27/00.

Investigating magnetic variable or properties

This subclass also covers, under group G01R 33/00, measuring or investigating magnetic properties of materials, whereas measuring or investigating non-magnetic or non-electric properties of materials by the use of magnetic means is covered by group G01N 27/72.

In particular, group G01R 33/20 covers measuring magnetic variables/properties by using magnetic resonance, e.g. NMR, EPR or other spin effects, whereas investigating or analysing materials by using such spin effects is covered by group G01N 24/00.

Concerning the "measuring of electric variables" part, the following applies when classifying: The most pertinent group is given as an EC. If several groups are equally pertinent (so if it is not clear which EC to allocate), several EC's or an EC and additional Indexing Codes are given.

General remark: G01R (electric part) is a big subclass with many low level subgroups. When classifying at group or subgroup level, care should taken to see to it that the document(s) really concern the measuring of an electric variable and that all higher level (subclass, group, subgroup) definitions are met with.

The scheme was created at a time when electromechanical instruments were common. The groups closely linked to such instruments are rarely used for classifying measuring or testing devices that fall under G01R.

It means what it says; many groups of G01R are not used any more, because the definitions are outdated (contrary to other fields we do not "bend" EC interpretations to fit present days technology.

Structural, tangible details of devices.

Details concerning arrangements of terminals for the testing of circuits, which do not fit into the definitions of G01R 1/04 and dependent subgroups, are classified in G01R 31/2886. Examples: Contacting devices or procedures without clear mechanical or geometrical features (as defined in the subgroups of G01R 1/04).

Test clips, which are contacting devices that clip onto the integrated circuit to be tested.

Probes for connecting to electric devices for measuring or testing purposes.

Connecting devices or methods for the testing of electrical circuits which do not fit into G01R 1/067 or a subgroup of G01R 1/067 are classified in G01R 31/2886.

Sockets, and details of sockets such as contacts, for receiving integrated circuits for testing are classified in G01R 1/0433.

Constructional details of individual probe elements or tips.

Geometric details where the dimensions are of microscopic dimensions, corresponding to features of integrated elements.

Details related to the material as such (alloy, heat treatment, surface deposit...)

Circuits being part of or closely linked to a probe, such as amplifiers, filters or power supplies integrated in a probe.

Probes adapted for the measuring of high frequencies, for example by having low inductance leads, low loss or linear frequency properties.

Probes specially adapted for measuring high voltages.

Probes having multiple contacting points

Probes mounted on a flexible membrane, such as so called "membrane probes".

Probes having long needles, which flex when pressed against the DUT.

Features related to geometrical adaption between probe tips and probe output, e.g. using an adapter board.

Manipulation of one or more individual probe elements, e.g. the tip part.

Instruments classified in this group may be used as indicating instruments for electric or non-electric variables.

Instruments classified in this group may be used as indicating instruments for electric or non-electric variables.

Electromechanical arrangements for measuring time integral of electric power or current such as conventional electromechanical electricity meters, i.e. comprising a rotating disk.

Unless one of the subgroups apply, add-ons, such as electronic counters or optical ports, are seen as "constructional details".

Housings for electromechanical electricity meters. "Supporting racks" are the internal supports for holding the Ferraris wheels, decade counters, transformers and other internal components of the electromechanical electricity meters. See e.g. US4791362, CH158284.

Housings which are used only for electronic meters are classified in G01R 22/065.

Supporting, cabinets comprising installation places for electricity meters but also other installation places e.g. for circuit breakers are classified in H02B 1/03.

If the arrangement for avoiding or indicating fraudulent use is related to electronic electricity meters the document should be classified in the corresponding subgroups of G01R 22/066 .

If the arrangement for indicating or signalling faults is related to electronic electricity meters the document should be classified in the corresponding subgroups of G01R 22/068 .

Oscilloscopes and the like for measuring and displaying waveforms.

If the document is directed to aspects of measuring of current or voltage (e.g. A/D conversion, signal conditioning) the classes G01R 19/2506 and lower take preference.

Modular arrangements for computer based systems (e.g. virtual systems) are classified in G01R 19/2516 (when the document is related to the measuring part).

Display by mechanical displacement only is classified in G01R 5/00, G01R 7/00, G01R 9/00.

Recording frequency spectrum is classified in G01R 23/18

All digital oscilloscopes.

Older type cathode-ray oscilloscopes using digital processors and intermediate A.D. and D.A. converters are classified in G01R 13/345.

If the emphasis is set on the current or voltage measuring part, e.g. signal conditioning, details concerning sampling, digitizing G01R 19/2506 and lower, as well as G01R 19/252, G01R 19/255 and G01R 19/257 take preference.

Modular arrangements for computer based systems are classified in G01R 19/2516.

When the type of the display is of importance, e.g. LCD display G01R 13/403 is used.

Systems for displaying a waveform by a table or the like with numerical values. Other characterising values, even single values, of waveforms are also covered here.

Displaying charts of waveforms are classified in G01R 13/0218 and lower and in G01R 13/029 or in the parent class G01R 13/02.

Details of sampling circuits when they are used only in digital oscilloscopes.

More general details of sampling are classified in G01R 19/2506 and lower. These classes can in cases of interest also be given in parallel.

Software used in digital oscilloscopes and the like.

If the software calculates a trigger event an additional class is given in G01R 13/0254 (although the title thereof relates to circuits). Similarly the other groups of G01R 13/0218 are given in parallel to G01R 13/029.

Analogue oscilloscopes with cathode-ray screens or oscilloscopes which have an intermediate digital part but which use a traditional cathode-ray screen.

Digital oscilloscopes are classified in G01R 13/02 and lower. If the type of display is of interest, G01R 13/40 and lower is used, e.g. G01R 13/403 for liquid crystal displays (LCD).

Circuits of analogue storage oscilloscopes.

Cathode-ray oscilloscopes whereby the intermediary signal processing is performed by a digital processor but the resulting waveform is converted back to an analogue signal to be displayed on the cathode-ray screen.

Documents where the type of the display of the oscilloscope is of interest.

Cathode ray oscilloscopes are classified in G01R 13/20 and lower. Digital oscilloscopes wherein the type of display is not of importance are classified in G01R 13/02 and lower.

Documents where the type of the display of the oscilloscope is of interest.

Cathode ray oscilloscopes are classified in G01R 13/20 and lower. Digital oscilloscopes wherein the type of display is not of importance are classified in G01R 13/02 and lower.

Measuring of voltage or through capacitive coupling with the conductor to be measured.

Measuring current or voltage using coils or transformers (having interacting windings; the primary winding can be made up by a straight conductor surrounded by the secondary).

Measuring of amplitude of periodic voltage or current is also covered.

Threshold detectors as such, when seen as a measurement circuit (for current or voltage).

Adaptations where the measured signals have wavelengths in the order of magnitude of the circuits present, i.e. high frequencies (theoretically, signals on very long conductors are also covered, but such applications are unusual).

Analogue and digital measurements of power or power factor.

Also measurements of power for high frequency signals.

This group covers additionally the measurement of power when it is an essential aspect of a measurement of electric energy (time integral of power).

Electronic measurements of energy (time integral of power) is classified in G01R 22/06 when the power measurement therein is not the essential part.

maximum load or demand monitors.

Power measurements whereby the wavelength comes into the geometrical order of the underlying medium, i.e. for very high frequencies.

Power measurements by thermal methods for high frequency signals.

Power measurements by thermal methods whereby the wavelength comes into the geometrical order of the underlying medium, i.e. for very high frequencies.

Power measurements by using voltage and current measurements whereby the wavelength comes into the geometrical order of the underlying medium, i.e. for very high frequencies.

Power measurements by using galvano-magnetic effect devices whereby the wavelength comes into the geometrical order of the underlying medium, i.e. for very high frequencies.

Power measurement for high frequency signals which use such square-law characteristics of circuit elements.

Power measurements by using square-law characteristics of circuit elements whereby the wavelength comes into the geometrical order of the underlying medium, i.e. for very high frequencies.

Power meters using a digital processor.

Additionally measurements of power in meters for electric energy (time integral of power) when the measurement of power is the essential aspect.

Digital energy meters (time integral of power) are classified in G01R 22/10 when the power measuring part thereof is not of main importance. However if the power measuring aspect in such digital energy meters is of main interest then it is classified here in G01R 21/133 and lower.

Digital measurements of voltages or currents in electric power systems are classified in G01R 19/2513, e.g. for monitoring the quality of the power signal.

Maximum load or maximum demand power meters.

Methods other than electromechanical for measuring time integral of electric power.

An arrangement for measuring time integral of electric power is classified in group G01R 21/00 if the essential characteristic is the measuring of electric power.

Electronic methods for measuring time integral of power, whereby analogue or digital techniques can be used.

Aspects of electricity meters for remote reading in the sense that the meter has special adaptations which go beyond standard communication systems.

Managing power networks by using distributed power monitors and using standard communication protocols is classified in H02J 13/00.

If the communication protocol as such is of interest the document is classified in H04B 1/00.

Housings specially adapted (or used only) for electronic electricity meters.

This group also covers adaptations to the housing of an electronic electricity meter in order to add a certain functionality and whereby mechanical aspects of this adaptation are of importance.

Electricity meters which are based on an analogue electronic circuit.

Digital arrangements for measuring time integral of electric power, such as electricity meters, whereby the digital processing is of importance.

Details relating to measuring of electric power are classified in G01R 21/133.

Digital measurements of voltages or currents in electric power systems are classified in G01R 19/2513, e.g. for monitoring the quality of the power signal.

Arrangements for measuring frequencies of electrical signals as such.

arrangements for analysing frequency spectra of electric signals if the analysis thereof comprises aspects of the determination of frequency components.

The mere use of known frequency measurement or analysis methods or devices is classified in the appropriate application class, such as G01N 27/00 or G01N 22/00.

Measurements of frequencies whereby the wavelength comes into the geometrical order of the underlying medium, i.e. for very high frequencies.

Measuring instruments using a resonant frequency, e.g. an oscillator output energy which changes in the vicinity of a resonant circuit which is tuned to the frequency the oscillator generates.

Frequency measurements wherein signals of different frequencies are combined in order to generate intermediate frequencies / interference signals which are used for the measurement (heterodyning).

Also frequency measurements based on a comparison to a signal of a similar reference frequency.

Frequency measurements wherein the reference signal is a harmonic signal of an (adjustable) oscillator.

Also digital determinations of a single frequency.

Spectrum-analysers and the like, e.g. digital spectrum analysers using algorithms performed on a microprocessor whereby the electric signal measurement apparatus, and not only a pure mathematical algorithm, is of interest.

Digital spectrum analysers are normally classified in this class unless one or more of the subgroups are relevant. The subgroups are however directed to devices for spectrum analysis which were not based on algorithm performed on microprocessors.

Determination of a single frequency is classified in G01R 23/15. Frequency selective measuring of voltage level is classified in G01R 19/04.

Spectrum analysis for frequencies whereby the wavelength comes into the geometrical order of the underlying medium, i.e. for very high frequencies.

Digital spectrum analysers using an algorithm performed on a microprocessor are classified in G01R 23/16.

For example devices which such provisions for recording in order to display the result on a screen.

The measurement of non-linear distortion by frequency analysis.

Phase measurements of electrical signals as such.

Phase measurements whereby the wavelength comes into the geometrical order of the underlying medium, i.e. for very high frequencies.

Measurements of resistance, reactance or impedance as such whereby the measurement comprises aspects which are not generally known in the art.

The use of such measurements is classified in the appropriate application places.

Measurements of complex impedance.

Groups G01R 27/02 - G01R 27/22 cover variables that directly or indirectly can be measured over two poles of a component or a Thevenin two-pole equivalent. Subgroup G01R 27/26 also covers other techniques, e.g. using electro-magnetic waves or network analyzers.

Measurements of capacitance only is classified in G01R 27/2605.

Measurements of inductance only is classified in G01R 27/2611.

Impedance measurements whereby the wavelength comes into the geometrical order of the underlying medium, i.e. for very high frequencies.

Measurements of resistance between a high voltage line and ground when current from another source is passing the high voltage line.

Measurements of resistance of lines which are intended for grounding, such as the resistance of the PE line or of the resistance of the earth as such.

Contact resistance measurements, e.g. of earth connections, but also of other connections, e.g. between terminal blades and sockets.

The group G01R 27/26 represents only a parent-class which is not actively used. Instead the groups G01R 27/2605 - G01R 27/2688 are used.

In cases where an impedance with a real and an imaginary part is determined, and none of the groups listed hereabove are relevant, the group G01R 27/02 is used.

Measurements of capacitance as such in the sense that particular steps of the measurement or particular features thereof are disclosed.

Only in very rare and exceptional cases where the capacity measurement has particular aspects capacitive sensors may be classified here.

The mere use of an existing capacity measurement method or device should not be classified in this group. In particular no sensors which are based on capacitance effects are classified here. Such sensors are classified in the classes of the corresponding applications.

Measurements of inductance as such in the sense that particular steps of the measurement or particular features thereof are disclosed.

Only in very rare and exceptional cases where the inductance measurement has particular aspects, sensors may be classified here.

Measurements of the relative permittivity or electric susceptibility X_e

or the like of a dielectric material.

Dielectric loss measurements e.g. of cables.

For example hf network analysers.

Calibrations of network analysers are classified in G01R 35/005 and G01R 27/28 in parallel if the network analyser differs from known network analysers.

The use of known network analysers for special applications is classified in the corresponding classes of the applications, e.g. for analysis of materials in G01N 27/00.

Measuring attenuation, gain, phase shift or derived characteristics of electric four pole networks whereby the wavelength comes into the geometrical order of the underlying medium, i.e. for very high frequencies, and this fact is essential for the invention.

Testing of antennas and/or measurements of radiation diagrams of aerials.

Indicating phase sequence or Indicating synchronism of power supply networks.

The measurement of charge often goes together with the measurement of the electrostatic field.

The classes G01R 29/12, G01R 15/165 and G01R 5/28 should therefore also be considered and in cases where the measurement of the electrostatic field as such is also of particular interest one of these classes can be given in parallel to G01R 29/24. Otherwise G01R 29/24 takes precedence for charge measurements.

The measurement of noise figure, signal-to-noise ratio and of jitter (phase noise).

Electric testing of electric devices.

Stress and burn-in testing, subjecting the DUT to hot or cold temperatures, radiation, vibration or similar.

Determining the exact location of a fault on a cable, transmission line or network.

Time domain and frequency domain reflectometry.

A raw wafer, not having any circuits or parts of circuits on it, is considered as an individual semiconductor element.

Testing of printed circuits, integrated and hard-wired circuits.

Statistical aspects of IC testing. Quality control procedures for IC testing.

Testing of integrated circuit packages as such, i.e. not involving the solid state circuits they surround.

Testing of electric aspects of electronic circuits using contact-less exchange of information or energy, e.g. contact-less exciting or signal-sampling.

Wireless exchange of information between tester apparatus and DUT during electronic testing of integrated circuits.

The testing, measuring or monitoring ̶ through electrical means ̶ of accumulators or electric batteries.

G01R 31/36 covers the testing, measuring or monitoring of accumulators or electric batteries taking place through electrical measurements. The testing, measuring or monitoring of batteries making use of other variables, e.g. ultrasonic measurements or chemical analysis of electrolyte, is covered in other subclasses, in particular subclasses G01N or H01M.

In particular, testing or monitoring of fuel cells by analysing reactants or residues is classified in subclass H01M.

Furthermore, electric testing arrangements structurally associated with the batteries are covered by H01M as shown by the references out of the residual place G01R 31/36.

The software aspect of testing of accumulators or electric batteries, e.g. computational or data processing aspects.

Examples include:

The testing, measuring or monitoring of accumulators or electric batteries where the electric-variable sensing and the display of the result occur in different locations, characterized by different environmental parameters, e.g. temperature, pressure, noise.

The display can be a system with another main function, e.g. a mobile phone, provided that that system does not encompass the battery-sensing element(s), although it could perform a controlling function on these elements.

Another example of subject matter covered in this group is an indicator mounted on a vehicle's dashboard, indicating the electrical condition of the vehicle's battery.

Methods to assess the condition of an individual cell or group or cells in a multi-cell battery, in which data are transmitted to processing means outside the battery, allowing the condition of a subset of cells (e.g. one) within the battery to be determined without dismantling the battery.

When electrochemical cells are tested or monitored through integrated means, as if they were stand-alone cells, classification is made in subclass H01M. G01R 31/396 covers the collecting and use or processing of data taking place outside the battery, but leading to knowledge of the condition of cells within the battery, without intrusive measurements.

Tests for open circuits (lack of continuity) .

Testing line connections, e.g. for correctness or for electrical characteristics.

Testing to validate the correct position or placement of conductors or connections, e.g. in a wiring loom.

Magnetic sensors and measuring aspects for measuring all kind of magnetic variables.

NMR is classified in the subgroups of G01R 33/20, but general aspects of measuring magnetic variables is classified in G01R 33/0005-M.

The different types of magnetic sensors.

G01R 33/0005 - G01R 33/0052 concern general aspects of measuring magnetic variables and may also be given as additional class to the sub-classes of G01R 33/02.

3D Magnetometers.

Apparatus and methods concerning measurements with charged or magnetic particles.

Gradiometers.

Devices using compensation measurements.

Magnetometers using the relationship between currents, magnetic fields and/or magnetic force.

All kind of MEMS devices.

All kind of magneto-optical devices and methods, e.g. Cotton-Mouton (magnetic double refraction in liquid, caused by lining-up of anisotropic molecules in magnetic field. Analogue of ELECTRO-optic Kerr effect, not related to Zeeman effect.)

e.g. Faraday effect (rotation of polarization plane of plane-polarized light, consequence of longitudinal Zeeman effect, field parallel to light beam); e.g. Voigt effect (magnetic double refraction, different diffraction for polarization parallel to field and polarization perpendicular to field, consequence of transverse Zeeman effect, field perpendicular to light beam)

E.g. Kerr magneto-optic effect (normally incident plane-polarized light becomes elliptically polarized in magnetic field. To be distinguished from ordinary elliptical polarization under oblique incidence and from electro-optical Kerr effect).

All aspects concerning the relationship between strain/stress/shape/volume of a material and a magnetic field/the magnetic properties of the material.

SQUIDs and superconductive magneto-resistance.

Magnetometers using the magneto-resistance in superconductors.

Fluxgate sensors.

Microfluxgate sensors, e.g. manufactured in CMOS technology.

Aspects concerning magneto-impedance.

This class does not concern the sensors as such, but the adaptation of their environment for specific applications.

AMR, GMR, TMR sensors.

This class does not concern the sensors as such, but the adaptation of their environment for specific applications.

GMR, spin valve and AMR sensors.

TMR sensors.

Imaging of magnetic variables.

Aspects of measuring the different magnetic variables and may be classified in addition to the sub-classes of G01R 33/02.

G01R 33/0005 - G01R 33/0052 may be considered additionally.

Qualification of hard disks and MRAMs.

Investigation of magnetic properties and critical current of superconductors is classified.

Magnetic Biosensors.

Spintronics devices.

Aspects concerning domain wall analysis and racetrack memories.

Hysteresis measurements.

Aspects concerning magnetic susceptibility measurements.

Equipment for making measurements involving magnetic resonance such as nuclear magnetic resonance [NMR], magnetic resonance imaging [MRI], electron paramagnetic resonance [EPR], nuclear quadrupole resonance [NQR] or other spin resonance effects;

Technical details of the equipment;

Testing or calibrating of the equipment;

Activities involved in making the measurements or in processing the signals collected during the measurements.

The following places may also be relevant for classification:

A61B 5/055: Detecting, measuring or recording for diagnostic purposes

involving electronic or nuclear magnetic resonance

There is an overlap between the scope of G01R 33/20 (or its relevant subgroup) and A61B 5/055 in the sense that, depending on the disclosure of a given document, the document may have to be classified in G01R 33/20 (or its relevant subgroup) only, in A61B 5/055 only or in both places.

For instance, if the invention information of a document to be classified was primarily directed to the MR process as such (e.g. a novel pulse sequence which, according to the document, facilitates the diagnosis of a disease on the basis of the resulting MR images wherein the document merely mentions the diagnosis but does not specifically disclose its implementation in detail), the document should be classified in G01R 33/20 (or its relevant subgroup) and the additional information related to the diagnosis may be classified using the appropriate Indexing Code corresponding to A61B 5/055.

However, if the invention information of the document was primarily directed to the diagnosis as such (e.g. a novel way of processing MRI data in order to enable the diagnosis of a disease wherein the MRI data was acquired using a commonly known standard MRI technique), the document should be classified in A61B 5/055 only.

G01N 24/00 : Investigating or analysing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects

There is an overlap between the scope of G01R 33/20 (or its relevant subgroup) and G01N 24/00 (or its relevant subgroup) in the sense that, depending on the disclosure of a given document, the document may have to be classified in G01R 33/20 (or its relevant subgroup) only, in G01N 24/00 (or its relevant subgroup) only or in both places.

For instance, if the invention information of a document to be classified was primarily directed to the MR process as such (e.g. a novel pulse sequence which, according to the document, can be applied for analyzing materials wherein the document merely mentions this application but does not specifically disclose its implementation in detail), the document should be classified in G01R 33/20 (or its relevant subgroup) and the additional information related to the potential application for analyzing materials may be classified using the appropriate Indexing Code corresponding to G01N 24/00 (or its relevant subgroup).

However, if the invention information of the document was primarily directed to the analysis of a material using a known standard MR technique, the document should be classified in G01N 24/00 (or its relevant subgroup) only.

G01V 3/32: Electric or magnetic prospecting or detecting specially adapted for well-logging operating with electron or nuclear magnetic resonance

There is an overlap between the scope of G01R 33/20 (or its relevant subgroup) and G01V 3/32 in the sense that, depending on the disclosure of a given document, the document may have to be classified in G01R 33/20 (or its relevant subgroup) only, in G01V 3/32 only or in both places.

For instance, if the invention information of a document to be classified was primarily directed to the MR process as such (e.g. a novel pulse sequence which, according to the document, can be applied for MR in a borehole wherein the document merely mentions this application but does not specifically disclose its implementation in detail), the document should be classified in G01R 33/20 (or its relevant subgroup) and the additional information related to the potential application in the borehole may be classified using the appropriate Indexing Code of G01V 3/32.

However, if the invention information of the document was primarily directed to geophysics aspects or the application of MR in a borehole, the document should be classified in G01V 3/32 only.

In this subgroup, classification of additional information, i.e. non-invention information, is compulsory using the appropriate Indexing Code (G01R 33/20 ... G01R 33/64).

Comments on subgroups:

G01R 33/323: For the purpose of classification in this subgroup, the expression "RF" is to be interpreted as referring to an RF magnetic field. Therefore, a document disclosing a technique of detecting MR using an RF electric field should be classified in this subgroup.

G01R 33/34046: For the purpose of classification in this subgroup, a "volume type coil" is to be understood as a coil which encloses the object to be investigated (in contrast to a surface coil which is positioned on a surface of the object to be investigated rather than enclosing the object).

G01R 33/34053: For the purpose of classification in this subgroup, a single-turn solenoid coil encircling the trunk of a patient to be investigated is understood as a volume type coil and therefore classified in subgroup G01R 33/34053.

In contrast thereto, a single-turn surface coil being placed on a surface of a patient is not understood as a volume type coil and should therefore not be classified in subgroup G01R 33/34053. Rather, classification symbol G01R 33/341 (or its subgroup G01R 33/3415) should be assigned in that case.

G01R 33/34061: For the purpose of classification in this subgroup, a Helmholtz coil is to be understood as any arrangement wherein two coils are placed symmetrically one on each side of the experimental area along a common axis.

Even if these coils are realized in the form of surface coils, the classification symbol G01R 33/341 should normally not be assigned.

G01R 33/34084 Implantable coils or coils being geometrically adaptable to the sample.

This subgroup does also cover coil assemblies with mutually movable parts, e.g. a Helmholtz coil assembly comprising two coils located on opposite sides of the trunk of a patient wherein the distance between the two coils can be adapted to the size of the trunk.

However, a single rigid surface coil which is mounted on a flexible mechanical support (e.g. a flexible arm) should not be classified in subgroup G01R 33/34084. Rather, classification symbol G01R 33/34007 should be assigned in that case.

G01R 33/3628: An RF coil being inductively matched to the transceiver in the sense that the RF coil is not galvanically connected to the transceiver, but only coupled to the transceiver via mutual inductance or mutual capacitance between the RF coil and a further coupling element (e.g. a driving coil), should not be classified in subgroup G01R 33/3628. Rather, classification symbol G01R 33/3642 should be assigned.

G01R 33/365 See comment under G01R 33/3657.

G01R 33/3657: For the purpose of classification in this subgroup as well as subgroup G01R 33/365, the "function" of the multiple RF coils is defined in relation to their use for spin excitation, MR signal reception or both.

For instance, an RF coil being used for exciting proton spins and another RF coil being used for exciting fluorine spins are therefore understood to perform the same function in MR, namely spin excitation.

G01R 33/4828: This group does not cover fat suppression which is to be classified under subgroup G01R 33/5607.

G01R 33/565: This subgroup does also cover the prevention of image distortions.

For instance, an RF coil being manufactured from susceptibility compensated wire, thereby preventing image distortions due to magnetic susceptibility variations, should be classified in the appropriate subgroup of G01R 33/565, probably using the corresponding Indexing Code (G01R 33/56536 in the example given above).

G01R 33/62: This subgroup covers the combined use of at least two different spin resonance techniques, e.g. the combined use of NMR and NQR.

This group does not cover RF coils being resonant at two distinct Larmor frequencies. Rather, such RF coils are covered by subgroup G01R 33/3635.

Calibrating of measuring devices such as network analysers, but also other measuring devices of the preceding groups.

Standards or reference devices comprising new aspects and being new over standards known in the art.