U.S. PATENT AND TRADEMARK OFFICE
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U.S. Patent Classification System - Classification Definitions
as of June 30, 2000
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Class 329
DEMODULATORS
Class Definition:
A. BASIC SUBJECT MATTER OF CLASS
This is the generic class for demodulators. A demodulator is
a device which extracts an arbitrarily varying information
carrying signal from a signal formed by varying a
characteristic of a repetitious electrical or electromagnetic
wave of less than infrared frequency in accordance with this
information carrying signal. Classification herein is
broadly by the type of modulation exhibited by the input
signal.
B. COMBINATIONS WITH BASIC SUBJECT MATTER INCLUDED IN THIS
CLASS
1. A demodulator combined with perfecting structure is
classified here. Such structure might include, for example,
a particular power supply for electronic devices within the
demodulator.
2. A demodulator combined with or incorporated in other
structure not otherwise classifiable is classified here.
This might include, for example, a demodulator combined with
an acoustical device such as a loudspeaker.
3. A combination including both a modulator and a
demodulator is classified elsewhere. See Lines With Other
Classes and Within This Class, below.
C. MISCELLANEOUS SYSTEMS AND DEVICES USED WITH DEMODULATORS
This class provides for (1) miscellaneous systems and devices
which are not of general utility and which are limited to use
with demodulators and (2) miscellaneous systems and devices
useful with demodulators which are not otherwise classified.
An example of this would be convertible demodulators which
convert between different types of demodulators or which
convert to or from devices other than demodulators.
LINES WITH OTHER CLASSES AND WITHIN THIS CLASS
A combination including both a modulator and a demodulator is
classified in Class 332 where such combination is not
provided for elsewhere.
Excluded from this class are pulse code demodulators and
delta modulation demodulators which are now classified
elsewhere. See References to other Classes, below.
Several classes contain structure which is closely analogous
to demodulators. Particularly significant among these is the
art in the class for miscellaneous active electrical
nonlinear devices, circuits, and systems. See the relevant
SEARCH CLASS notes below in References to Other Classes in
completing the search for subject matter of Class 329.
Many classes contain subject matter which includes
demodulators or analogous devices as subcombinations thereof.
Among these are receivers and complete communication systems
(i.e., transmitters and receivers). (See References to Other
Classes, below.) Therefore, these classes and others
contained in the SEARCH CLASS notes below in References to
Other Classes, should be considered in completing the search
for subject matter of Class 329.
The terms "discriminator" and "detector" are often but not
always used synonymously with "demodulator". Classification
in Class 329 is appropriate where the terms "discriminator"
or "detector" are recited and which clearly disclose a
corresponding function of demodulation per the definition
above. Classification is elsewhere where no such disclosure
is present. See the SEARCH CLASS notes below in References
to Other Classes, particularly those for the class for
miscellaneous active electrical nonlinear devices, circuits,
and systems.
Demodulators having a modulated input of less than infrared
frequency which may utilize an internal optical element
(e.g., an optical isolator) are classified in Class 329 by
the type of modulation.
The combination of modulation converter (e.g., FM to AM) with
a demodulator is classified in Class 329 according to the
modulation type of the input to the converter. Modulation
converters, per se, are classified elsewhere. See References
to Other Classes, below.
For classification herein there must be complete extraction
of the modulating signal. Mere frequency converters (e.g.,
RF to IF mixers) are not classified here. See References to
Other Classes, below.
Class 329 provides for demodulators, per se, with structure
for noise or distortion control (see Subclass References to
the Current Class, below). Class 455, Telecommunications,
provides for noise or interference control in: (a) a
telecommunication system (i.e., transmitter and receiver);
(b) a complete telecommunication receiver; and (c) a
combination of two or more receiver elements (viz. wave
collector, wave mixer or modifier, demodulator, and
utilization device) where the combination is not elsewhere
classified. Therefore, consideration must be given to
extending the search for demodulator noise control circuitry
into relevant subclasses of Class 455. See also the SEARCH
CLASS notes in References to Other Classes, below, relating
to Class 455.
Subclasses of this class (329) relate to suppressed carrier
double sideband demodulators, per se, and single/vestigial
sideband demodulators, per se (see Subclass References to
the Current Class, below). Class 455 accepts this subject
matter in combination with what may be broadly recited
diverse receiver elements (viz. wave collector, wave modifier
or mixer, and utilization device). Therefore, in completing
the search for demodulators of an amplitude modulated wave
not having the full complement of carrier and two complete
sidebands, consideration must be given to extending the
search to relevant subclasses in Class 455. See also the
SEARCH CLASS notes in References to Other Classes, below,
relating to Class 455.
SEE OR SEARCH THIS CLASS, SUBCLASS:
318 and 349+ for demodulators, per se, with structure for
noise or distortion control.
356 for suppressed carrier double sideband demodulators, per
se.
357 single/vestigial sideband demodulators, per se.
REFERENCES TO OTHER CLASSES
SEE OR SEARCH CLASS:
73, Measuring and Testing, appropriate subclasses for
measuring or testing of a parameter which is typically
neither electrical, optical, thermal, nor chemical and which
may include a demodulation technique.
178, Telegraphy, 66.1 for a teles:graphic system which
transmits messages between stations using alternating or
pulsating currents and particularly subclass 66.2 for such a
system having a transmitter which is turned on and off,
subclass 117 for a teles:graphic system utilizing a coherer,
and subclasses 118+ for teles:graphic receivers in general.
250, Radiant Energy, appropriate subclasses for the detection
of invisible radiation or the testing of material by
invisible radiation which may include a modulation -
demodulation technique.
257, Active Solid-State Devices (e.g., Transistors,
Solid-State Diodes), appropriate subclasses for active
solid-state devices used as demodulators, including subclass
10, 11, 21, 53-56, 113-118, 184-189, 225-234, 257-258,
290-294, and 414-466 for radiation-sensitive active
semiconductor devices.
307, Electrical Transmission or Interconnection Systems, 401
for miscellaneous nonlinear reactor systems.
310, Electrical Generator or Motor Structure, 311 for
piezoelectric elements and devices.
313, Electric Lamp and Discharge Devices, appropriate
subclasses for the structure of electronic tubes.
315, Electrical Lamp and Discharge Devices: Systems, 1 for
cathode-ray tube circuits with power supply or the
combination of cathode-ray tube and circuit element in a
unitary device, and subclasses 94+ for an electron discharge
device which is an ultimate load together with a cathode or
cathode heater supply circuit.
318, Electricity: Motive Power Systems, 606 for servo
systems utilizing a feedback signal which frequency or phase
modulates a system carrier (particularly subclasses 607 and
608 for obtaining the modulating wave by reference signal
frequency or phase comparison, respectively) subclass 622 for
an AC lead or lag network which may include a demodulation
technique, and subclasses 671+ for particular servo system
motor control (particularly subclass 684 which utilizes a
specific demodulator).
323, Electricity: Power Supply or Regulation Systems,
appropriate subclasses for control of the magnitude or phase
of current or voltage in a system comprising a single
electrical source coupled to a single electrical load.
324, Electricity: Measuring and Testing, appropriate
subclasses for measurement of electrical properties, in
general, and particularly 76.11 for systems measuring and
testing electricity which may include demodulation,
particularly subclasses 76.39+ for frequency measurement and
subclasses 76.77+ for phase comparison, and subclass 118 for
modulation of voltage or current to be measured onto a
carrier combined with subsequent structure to recover a
replica of the original voltage or current by demodulation.
327, Miscellaneous Active Electrical Nonlinear Devices,
Circuits, and Systems, 1 for miscellaneous signal parameter
discriminating or comparing for input signals not carrying
intelligence, particularly subclasses 2+ for miscellaneous
phase discriminating, subclasses 31+ for miscellaneous pulse
spacing discriminating, subclasses 39+ for miscellaneous
frequency discriminating, and subclasses 50+ for
miscellaneous amplitude discriminating. (See Lines With Other
Classes, above)
330, Amplifiers, subclass 10 for an amplifier having an
input which is the output of a modulator and an output which
is the input of a subsequent demodulator.
331, Oscillators, 1 for automatic oscillator frequency
stabilization using phase or frequency sensing which may
include comparison with a reference oscillator or a
modulation technique, subclasses 46+ for plural oscillator
systems in general, and subclass 58 for an oscillator with
structure to perform an additional simultaneous function.
332, Modulators, 100 for a frequency shift keying modulator,
subclasses 103+ for a phase shift keying modulator,
subclasses 106+ for a pulse modulator, subclasses 117+ for a
frequency modulator, subclasses 144+ for a phase modulator
and subclasses 149+ for an amplitude modulator; subclasses
183+ for modulation converters, per se.
333, Wave Transmission Lines and Networks, 24 for
transmission line coupling networks (particularly subclasses
25+ for balanced to unbalanced circuits, subclasses 138+ for
lumped parameter delay lines, and subclasses165 - 212 for
filters), subclasses 236+ for long lines, per se, and
subclasses 245+ for long line elements and components.
334, Tuners, appropriate subclasses for tuner circuits, per
se, which may include a broad recitation of a demodulator
plus details of a tuner and particularly 30 for a tuner with
a resonance indicator in which a demodulator may be used and
subclass 39 for tuners combined with other devices which may
include a demodulator recited broadly.
336, Inductor Devices, appropriate subclasses for electrical
circuit elements exhibiting inductive properties.
338, Electrical Resistors, subclass 1 for a coherer-type
resistor and subclasses 13+ for a resistor whose resistance
value varies in response to a condition such as temperature
or magnetic field.
340, Communications: Electrical, 870.01 for telemetry
systems and especially subclasses 870.18+ indented thereunder
for such systems where the quantity to be telemetered is
imposed on a carrier by a particular type of modulation.
341, Coded Data Generation or Conversion, 126 for a pulse
code demodulator, per se, and subclass 143 for a delta
modulation demodulator, per se.
342, Communications: Directive Radio Wave Systems and Devices
(e.g., Radar, Radio Navigation), 350 for directive radio
wave systems which may include demodulation techniques and
particularly subclasses 385+ for a directive beacon or
receiver.
348, Television, 638 for a demodulator particularly adapted
for extracting a component of a natural color television
signal from a carrier or subcarrier, subclasses 726+ for
television signal receivers and subcombination thereof.
358, Facsimile and Static Presentation Processing, subclass
469 for modulation onto a carrier of a facsimile signal
derived from scanning a picture or for demodulation of such a
modulated carrier to reconstruct the picture.
360, Dynamic Magnetic Information Storage or Retrieval,
subclass 28 for control of a demodulator by a reference
carrier signal stored concurrently with the information
signal to be demodulated and subclasses 29+ for dynamic
magnetic recording or reproducing containing particular
demodulator circuitry.
363, Electric Power Conversion Systems, particularly 13 for
current conversion which includes generic AC to DC rectifiers
and generic DC to AC inverters of diverse type.
367, Communications, Electrical: Acoustic Wave Systems and
Devices, subclass 134 for acoustic wave demodulation in an
underwater telemetry system.
369, Dynamic Information Storage or Retrieval, subclass 90
for demodulation of a previously modulated quadraphonic
subchannel signal after retrieval.
370, Multiplex Communications, appropriate subclasses for
multiplexing systems which may utilize demodulation
techniques.
374, Thermal Measuring and Testing, appropriate subclasses
for measurement systems responsive to an external thermal
condition which may utilize a modulation technique.
375, Pulse or Digital Communications, appropriate subclasses
for demodulators combined with receiving structure to couple
a modulated pulse wave from a transmission medium (i.e., a
receiver) or complete systems (i.e., transmitter and
receiver) incorporating such a combination, particularly
subclasses 237-242 + for a system or receiver utilizing
pulse number modulation, pulse width modulation, pulse
position, frequency, or spacing modulation, pulse amplitude
modulation, or pulse code modulation, subclasses 259+ for
other diverse types of digital communication systems which
may include a particular demodulator, and subclasses 316+ for
other diverse types of digital communication receivers which
may include a particular demodulator. (also see Lines With
Other Classes, above)
380, Cryptography, for all electrical communications
equipment which process an information signal for purposes of
concealment.
381, Electrical Audio Signal Processing Systems and Devices,
1 for broadcast stereophonic signal processing not elsewhere
classified.
386, Television Signal Processing for Dynamic Recording or
Reproducing, 26 for frequency modulation of a color
television signal.
455, Telecommunications, appropriate subclasses for
nondigital demodulators combined with receiving structure to
couple a modulated wave from a transmission medium (i.e., a
receiver) or complete systems (i.e., transmitter and
receiver) incorporating such a combination, particularly
subclass 21 for frequency conversion in a repeater including
a demodulator, subclasses 39+ for separated transmitter and
receiver which may include a particular demodulator,
subclasses 73+ for a transceiver which may include a
particular demodulator, and subclasses 130+ for a
telecommunications receiver which may include a particular
demodulator; subclasses 202 and 204 for suppressed carrier
double sideband demodulators, per se, and single/vestigial
sideband demodulators, in combination with what may be
broadly recited diverse receiver elements (viz. wave
collector, wave modifier or mixer, and utilization device);
subclasses 313+ for mere frequency converters (e.g., RF to IF
mixers). (also see Lines With Other Classes, above)
GLOSSARY:
ARBITRARILY VARYING
Indicates having a future value which is not predictable from
past values. (Arbitrary is the opposite of repetitious).
CARRIER
An electrical or electromagnetic repetitious sinusoidal
wave.
CHARACTERISTIC
An attribute associated with the size or shape of a wave or
signal. Examples are amplitude, frequency, or phase of a
sine wave and repetition rate, position, amplitude, or width
of a nonsine wave.
DEMODULATOR
A device which extracts an arbitrarily varying modulating
signal from an electrical or electromagnetic modulated signal
of less than infrared frequency.
MODULATED SIGNAL
A repetitious wave which has had a characteristic thereof
varied by a modulating signal.
MODULATING SIGNAL
An information carrying signal whose informational content is
to be impressed on a carrier or pulse wave.
MODULATOR
A device which varies a characteristic of a repetitious
electrical or electromagnetic wave of less than infrared
frequency in accordance with a characteristic of an
arbitrarily varying modulating signal.
PULSE WAVE
An electrical or electromagnetic repetitious nonsinusoidal
wave. Examples are square wave, saw-tooth wave, or
trapezoidal wave.
REPETITIOUS WAVE
A cyclic wave whose individual component cycles are
substantially identical. Examples of repetitious waves are
sine waves, square waves, saw-tooth waves and trapezoidal
waves.
SUBCLASSES
Subclass:
300
FREQUENCY SHIFT KEYING OR MINIMUM SHIFT KEYING DEMODULATOR:
This subclass is indented under the class definition.
Subject matter where the demodulator extracts the modulating
signal from a signal which has undergone frequency shift
keying modulation or minimum shift keying modulation.
(1) Note. Frequency shift keying modulation occurs when the
frequency of a carrier is shifted among a plurality of
discrete values in accordance with the modulating signal.
(2) Note. Minimum shift keying modulation is a type of
frequency shift keying modulation in which there is phase
continuity at the frequency transition points.
(3) Note. This subclass includes frequency shift keying
demodulators, per se. See the SEARCH CLASS notes below for
combinations with the subject matter of this subclass.
SEE OR SEARCH THIS CLASS, SUBCLASS:
304 for a phase shift keying demodulator.
SEE OR SEARCH CLASS:
375, Pulse or Digital Communications, 272 for a frequency
shift keying system (i.e., transmitter and receiver) and
subclasses 322+ for a frequency shift keying demodulator
combined with receiving structure.
Subclass:
301
Including discrete semiconductor device:
This subclass is indented under subclass 300. Subject matter
containing an electrical device whose constituent portions
are constructed from solid material having room temperature
conductivity between that of a conductor and an insulator and
which conductivity is typically modified through the addition
of small amounts of dopant.
(1) Note. This might include, for example, semiconductor
diodes or transistors of diverse type.
Subclass:
302
Input signal combined with local oscillator or carrier
frequency signal:
This subclass is indented under subclass 300. Subject matter
where the modulated signal input to the demodulator interacts
with oscillations from a secondary source.
(1) Note. The secondary oscillations may be internally
generated or externally supplied and may be at a frequency
other than that of the modulated input signal's carrier.
SEE OR SEARCH THIS CLASS, SUBCLASS:
306 for similar structure in a phase shift keying or
quadrature amplitude demodulator.
323 for similar structure in a frequency modulation
demodulator.
346 for similar structure in a phase modulation
demodulator.
358 for similar structure in an amplitude modulation
demodulator.
Subclass:
303
Including logic element (e.g., logic gate or flip-flop):
This subclass is indented under subclass 300. Subject matter
containing a component which performs a Boolean Algebraic
operation.
(1) Note. Such components may be combinational or
sequential (e.g., AND gates, OR gates or J-K flip-flops).
Subclass:
304
PHASE SHIFT KEYING OR QUADRATURE AMPLITUDE DEMODULATOR:
This subclass is indented under the class definition.
Subject matter where the demodulator extracts the modulating
signal from a signal which has undergone phase shift keying
modulation or quadrature amplitude modulation.
(1) Note. Phase shift keying modulation occurs when the
phase of a carrier is shifted among a plurality of discrete
angles in accordance with the modulating signal.
(2) Note. Quadrature amplitude modulation occurs when the
phase and amplitude of a carrier is simultaneously shifted
among a plurality of discrete angle/magnitude pairs.
(3) Note. This subclass includes phase shift keying
demodulators or quadrature amplitude demodulators, per se.
See the SEARCH CLASS notes below for combinations with the
subject matter of this subclass.
SEE OR SEARCH THIS CLASS, SUBCLASS:
300 for a frequency shift keying demodulator.
SEE OR SEARCH CLASS:
375, Pulse or Digital Communications, subclass 261 for a
quadrature amplitude modulation system (i.e., transmitter and
receiver), subclasses 279+ for a phase shift keying system,
and subclasses 322+ for a phase shift keying demodulator
combined with receiving structure.
Subclass:
305
Including discrete semiconductor device:
This subclass is indented under subclass 304. Subject matter
containing an electrical device whose constituent portions
are constructed from solid material having room temperature
conductivity between that of a conductor and an insulator and
which conductivity is typically modified through the addition
of small amounts of dopant.
(1) Note. This might include, for example, semiconductor
diodes or transistors of diverse type.
Subclass:
306
Input signal combined with local oscillator or carrier
frequency signal:
This subclass is indented under subclass 304. Subject matter
where the modulated signal input to the demodulator interacts
therein with oscillations from a secondary source.
(1) Note. The secondary oscillations may be internally
generated or externally supplied and may be at a frequency
other than that of the modulated input signal's carrier.
SEE OR SEARCH THIS CLASS, SUBCLASS:
302 for similar structure in a frequency shift keying or
minimum shift keying demodulator.
323 for similar structure in a frequency modulation
demodulator.
346 for similar structure in a phase modulation
demodulator.
358 for similar structure in an amplitude modulation
demodulator.
Subclass:
307
Including phase or frequency locked loop:
This subclass is indented under subclass 306. Subject matter
in which a phase or frequency locked loop provides stability
to or synchronization with the secondary source of
oscillations.
SEE OR SEARCH CLASS:
331, Oscillators, 1 for phase or frequency locked loops, per
se.
375, Pulse or Digital Communications, subclass 327 and 376
for phase locked loops in digital receivers or synchronizers,
respectively.
Subclass:
308
With parallel signal combiners (e.g., costas loop):
This subclass is indented under subclass 307. Subject matter
utilizing a plurality of signal combiners where the modulated
input signal is combined with relatively phase shifted
versions of the secondary oscillations, or where the
secondary oscillations are combined with relatively phase
shifted versions of the modulated input signal.
Subclass:
309
Including logic element (e.g., logic gate or flip-flop):
This subclass is indented under subclass 308. Subject matter
containing a component which performs a Boolean Algebraic
operation.
(1) Note. Such components may be combinational or
sequential (e.g., AND gates, OR gates or J-K flip-flops).
Subclass:
310
Including logic element (e.g., logic gate or flip-flop):
This subclass is indented under subclass 304. Subject matter
containing a component which performs a Boolean Algebraic
operation.
(1) Note. Such components may be combinational or
sequential (e.g., AND gates, OR gates or J-K flip-flops).
Subclass:
311
PULSE OR INTERRUPTED CONTINUOUS WAVE DEMODULATOR:
This subclass is indented under the class definition.
Subject matter where the demodulator extracts the modulating
signal from a modulated signal which has undergone pulse
modulation.
(1) Note. Pulse modulation occurs when a repetitious pulse
wave has a characteristic varied in accordance with the
modulating signal.
(2) Note. Interrupted continuous wave modulation occurs
when a pulsed continuous wave has a characteristic varied in
accordance with the modulating signal.
(3) Note. Examples of pulse waves are square waves,
sawtooth waves, and trapezoidal waves.
(4) Note. Comparable structure having an input which is
pulse code modulated (PCM) or delta modulated are found
elsewhere. See the Search Notes below.
(5) Note. This subclass includes pulse demodulators, per
se. See the SEARCH CLASS notes below for combinations with
the subject matter of this subclass.
SEE OR SEARCH THIS CLASS, SUBCLASS:
315 for a frequency modulation demodulator.
341 for an FM demodulator which initially transforms the
input signal into pulses.
345 for a phase modulation demodulator.
347 for an amplitude modulation demodulator.
SEE OR SEARCH CLASS:
341, Coded Data Generation or Conversion, 126 or 143 for a
structure comparable structure to this subclass (311) having
an input which is pulse code modulated (PCM) or delta
modulated.
375, Pulse or Digital Communications, appropriate subclasses,
for combinations of a pulse demodulator with receiving
structure.
Subclass:
312
Pulse width demodulator:
This subclass is indented under subclass 311. Subject matter
where the modulated signal input to the demodulator has
undergone pulse width modulation.
(1) Note. Pulse width modulation is a form of pulse
modulation in which the width (duration) of the pulses is the
characteristic that is varied.
SEE OR SEARCH CLASS:
375, Pulse or Digital Communications, subclass 238 or 340+
for a combination of pulse width demodulator with receiving
structure.
Subclass:
313
Pulse position, frequency, phase or spacing demodulator:
This subclass is indented under subclass 311. Subject matter
where the modulated signal input to the demodulator has
undergone pulse position, frequency, phase or spacing
modulation.
(1) Note. Pulse position, frequency, phase or spacing
modulation are forms of pulse modulation where the
characteristics being varied are the relative positions of
the pulses, the frequency (repetition rate) of the pulses,
the phase of the pulses, or the spacing (time) between the
pulses.
SEE OR SEARCH CLASS:
375, Pulse or Digital Communications, subclass 239 or 340+
for a combination of pulse position, frequency or spacing
demodulator with receiving structure.
Subclass:
314
Including discrete semiconductor device:
This subclass is indented under subclass 313. Subject matter
containing an electrical device whose constituent portions
are constructed from solid material having room temperature
conductivity between that of a conductor and an insulator and
which conductivity is typically modified through the addition
of small amounts of dopant.
(1) Note. This might include, for example, semiconductor
diodes or transistors of diverse type.
Subclass:
315
FREQUENCY MODULATION DEMODULATOR:
This subclass is indented under the class definition.
Subject matter where the demodulator extracts the modulating
signal from a modulated signal which has undergone frequency
modulation.
(1) Note. Frequency modulation occurs when the frequency of
a carrier is varied over a continuum of values in accordance
with the modulating signal.
(2) Note. This subclass includes frequency modulation
demodulators, per se. See the SEARCH CLASS notes below for
combinations with subject matter of this subclass.
SEE OR SEARCH THIS CLASS, SUBCLASS:
300 for a frequency shift keying or minimum shift keying
demodulator.
311 for a pulse modulation demodulator.
345 for a phase modulation demodulator.
347 for an amplitude modulation demodulator.
SEE OR SEARCH CLASS:
455, Telecommunications, 42 for frequency demodulation in a
system with separated transmitter and receiver, and
subclasses 205+ for a combination of frequency demodulator
with receiving structure.
Subclass:
316
Plural demodulation:
This subclass is indented under subclass 315. Subject matter
which utilizes a diverse intermediate type of demodulator
within the FM demodulator or combines the outputs of a
plurality of FM demodulators or has an output selectable from
a plurality of demodulators one of which must be an FM type.
Subclass:
317
Including amplitude demodulation:
This subclass is indented under subclass 316. Subject matter
which utilizes an intermediate amplitude demodulator.
Subclass:
318
Having specific distortion, noise or other interference
prevention, reduction or compensation:
This subclass is indented under subclass 315. Subject matter
including the neutralization of an undesirable characteristic
of a frequency modulation demodulator or its signals.
SEE OR SEARCH THIS CLASS, SUBCLASS:
349 for distortion or noise control in an amplitude
modulation demodulator.
SEE OR SEARCH CLASS:
455, Telecommunications, 63 and 501+ for noise control in a
telecommunication system with separated transmitter and
receiver, subclasses 210+ for carrier amplitude modulation
elimination in an FM receiver and subclasses 296+ for
receiver noise or interference control, particularly
subclasses 309 and 312.
Subclass:
319
Using feedback to reduce distortion, noise or other
interference:
This subclass is indented under subclass 318. Subject matter
which utilizes a returned portion of the output signal to
achieve neutralization.
Subclass:
320
By cancelling distortion, noise or other interference:
This subclass is indented under subclass 318. Subject matter
which combines a derived error or deviation signal with an
intermediate demodulator signal to achieve neutralization of
an undesirable characteristic in the final demodulator
output.
Subclass:
321
Using amplitude limiting within the demodulator:
This subclass is indented under subclass 318. Subject matter
which restricts the magnitude of signal fluctuations within
the demodulator itself to achieve the neutralization.
SEE OR SEARCH CLASS:
455, Telecommunications, 308 and particularly subclass 309
for amplitude limiting in a receiver noise elimination
structure.
Subclass:
322
Including microwave or distributed parameter structure:
This subclass is indented under subclass 315. Subject matter
utilizing a structure or device which is peculiar to
microwave frequencies or which has resistance, inductance or
capacitance not concentrated in lumped circuit elements.
SEE OR SEARCH THIS CLASS, SUBCLASS:
354 for similar structure in an amplitude modulation
demodulator.
Subclass:
323
Input signal combined with local oscillator or carrier
frequency signal:
This subclass is indented under subclass 315. Subject matter
where the modulated signal input to the demodulator interacts
therein with oscillations from a secondary source.
(1) Note. The secondary oscillations may be internally
generated or externally supplied and may be at a frequency
other than that of the modulated input signal's carrier.
SEE OR SEARCH THIS CLASS, SUBCLASS:
302 for similar structure in a frequency shift keying or
minimum shift keying demodulator.
306 for similar structure in a phase shift keying or
quadrature amplitude demodulator.
346 for similar structure in a phase modulation
demodulator.
358 for similar structure in an amplitude modulation
demodulator.
SEE OR SEARCH CLASS:
455, Telecommunications, 208 for synchronized or controlled
local oscillator in a FM receiver and subclasses 255+ for
generic local oscillator frequency control in a receiver.
Subclass:
324
Input signal applied directly to local oscillator:
This subclass is indented under subclass 323. Subject matter
in which the modulated input signal has a direct interaction
with the secondary source of oscillations and where the
modulating signal is extracted directly therefrom.
Subclass:
325
Including phase or frequency locked loop:
This subclass is indented under subclass 323. Subject matter
in which a phase or frequency locked loop provides stability
to the secondary source of oscillations.
SEE OR SEARCH CLASS:
331, Oscillators, 1 for phase or frequency locked loops, per
se.
455, Telecommunications, subclass 260 for phase lock loop or
frequency synthesizer in a receiver.
Subclass:
326
Including discrete semiconductor device:
This subclass is indented under subclass 325. Subject matter
containing an electrical device whose constituent portions
are constructed from solid material having room temperature
conductivity between that of a conductor and an insulator and
which conductivity is typically modified through the addition
of small amounts of dopant.
(1) Note. This might include, for example, semiconductor
diodes or transistors of diverse type.
Subclass:
327
Input signal split into plural signals:
This subclass is indented under subclass 315. Subject matter
where the modulated signal input to the demodulator is
separated into a plurality of closely analogous or identical
representations.
SEE OR SEARCH THIS CLASS, SUBCLASS:
363 for input signal splitting in an AM demodulator.
Subclass:
328
Including piezoelectric resonant element:
This subclass is indented under subclass 327. Subject matter
which incorporates a resonant component having the ability to
transform mechanical energy into electrical energy (e.g.,
piezoelectric).
(1) Note. Piezoelectric resonant elements are typically
crystals.
SEE OR SEARCH CLASS:
310, Electrical Generator or Motor Structure, 311 for
piezoelectric elements, per se.
Subclass:
329
Using a transformer to split input signal:
This subclass is indented under subclass 327. Subject matter
in which the separated signal representations are obtained at
the various wound portions of a transformer (e.g., primary or
secondary windings).
Subclass:
330
Signals taken from primary and secondary windings:
This subclass is indented under subclass 329. Subject matter
where representations of the modulated input signal are
extracted from the primary and the secondary windings of the
transformer.
Subclass:
331
Including plural detector diodes (e.g., ratio detector
type):
This subclass is indented under subclass 330. Subject matter
which additionally utilizes a plurality of diodes in
demodulation.
(1) Note. An example of this structure is a ratio detector
where the ratio of a pair of diode rectified currents is
proportional to frequency variations of an input signal.
Subclass:
332
Signals taken from plural secondary windings:
This subclass is indented under subclass 329. Subject matter
where representations of the modulated input signal are
extracted from plural secondary windings of the transformer.
Subclass:
333
Including plural detector diodes (e.g., ratio detector
type):
This subclass is indented under subclass 332. Subject matter
which additionally utilizes a plurality of diodes in
demodulation.
(1) Note. An example of this structure is a ratio detector
where the ratio of a pair of diode rectified currents is
proportional to frequency variations of an input signal.
Subclass:
334
Including resonant circuits tuned above and below input
signal carrier frequency:
This subclass is indented under subclass 333. Subject matter
which additionally utilizes a pair of tuned circuits having
resonant frequencies above and below the carrier frequency of
the input signal.
Subclass:
335
Including plural detector diodes (e.g., ratio detector
type):
This subclass is indented under subclass 329. Subject matter
which additionally utilizes a plurality of diodes in
demodulation.
(1) Note. An example of this structure is a ratio detector
where the ratio of a pair of diode rectified currents is
proportional to frequency variations of an input signal.
Subclass:
336
Input signal combined with phase shifted or delayed portion
of input signal:
This subclass is indented under subclass 327. Subject matter
in which an unmodified modulated signal is subsequently
combined with a time delayed version thereof.
(1) Note. Such a time delay can also be considered to be a
phase shift.
SEE OR SEARCH CLASS:
455, Telecommunications, subclass 304 for phase shifting
among plural signal paths used in receiver noise
elimination.
Subclass:
337
Including lc resonant phase shift circuit:
This subclass is indented under subclass 336. Subject matter
in which an inductive-capacitive resonant network provides
the required phase shift.
Subclass:
338
Input signal split by lc resonant circuit:
This subclass is indented under subclass 327. Subject matter
in which the input signal is separated into plural
representations by an inductive-capacitive resonant circuit.
Subclass:
339
Including lc resonant circuits tuned above and below input
signal carrier frequency:
This subclass is indented under subclass 338. Subject matter
utilizing a pair of inductive-capacitive tuned circuits
having resonant frequencies above and below the carrier
frequency of the input signal.
Subclass:
340
Including plural detector diodes (e.g., ratio detector
type):
This subclass is indented under subclass 327. Subject matter
which additionally utilizes a plurality of diodes in
demodulation.
(1) Note. An example of this structure is a ratio detector
where the ratio of a pair of diode rectified currents is
proportional to frequency variations of an input signal.
Subclass:
341
Input signal converted to and processed in pulse form (e.g.,
pulse counter or digital type demodulator):
This subclass is indented under subclass 315. Subject matter
in which the frequency modulated input signal is first
changed to a pulse equivalent and then processed.
SEE OR SEARCH THIS CLASS, SUBCLASS:
311 for pulse demodulators, per se.
Subclass:
342
Including discrete semiconductor device:
This subclass is indented under subclass 341. Subject matter
containing an electrical device whose constituent portions
are constructed from solid material having room temperature
conductivity between that of a conductor and an insulator and
which conductivity is typically modified through the addition
of small amounts of dopant.
(1) Note. This might include, for example, semiconductor
diodes or transistors of diverse type.
Subclass:
343
Including digital logic circuitry:
This subclass is indented under subclass 341. Subject matter
which includes processing circuitry which is not exclusively
of an analog nature.
(1) Note. Such components include, for example, AND gates,
OR gates, and J-K flip-flops.
Subclass:
344
Input signal passed through single demodulating path
including resonant circuit:
This subclass is indented under subclass 315. Subject matter
in which the modulated input signal transits a single
demodulating circuit path which contains a tuned circuit.
Subclass:
345
PHASE MODULATION DEMODULATOR:
This subclass is indented under the class definition.
Subject matter where the demodulator extracts the modulating
signal from a modulated signal which has undergone phase
modulation.
(1) Note. Phase modulation occurs when the phase of a
carrier is varied over a continuum of values in accordance
with the modulating signal.
(2) Note. This subclass includes phase modulation
demodulators, per se. See SEARCH CLASS notes below for
combinations with the subject matter of this subclass.
SEE OR SEARCH THIS CLASS, SUBCLASS:
304 for a phase shift keying or quadrature amplitude
demodulator.
311 for a pulse demodulator.
315 for a frequency demodulator.
347 for an amplitude demodulator.
SEE OR SEARCH CLASS:
455, Telecommunications, 42 for phase demodulation in a
system with separated transmitter and receiver, and
subclasses 205+ for a combination of phase demodulator with
receiving structure.
Subclass:
346
Input signal combined with local oscillator or carrier
frequency signal:
This subclass is indented under subclass 345. Subject matter
where the modulated signal input to the demodulator interacts
therein with oscillations from a secondary source.
(1) Note. The secondary oscillations may be internally
generated or externally supplied and may be at a frequency
other than that of the modulated input signal's carrier.
SEE OR SEARCH THIS CLASS, SUBCLASS:
302 for similar structure in a frequency shift keying or
minimum shift keying demodulator.
306 for similar structure in a phase shift keying or
quadrature amplitude demodulator.
323 for similar structure in a frequency modulation
demodulator.
358 for similar structure in an amplitude modulation
demodulator.
SEE OR SEARCH CLASS:
455, Telecommunications, 208 for a synchronized or
controlled local oscillator in a phase modulation receiver
and subclasses 255+ for generic local oscillator frequency
control in a receiver.
Subclass:
347
AMPLITUDE MODULATION DEMODULATOR:
This subclass is indented under the class definition.
Subject matter where the demodulator extracts the modulating
signal from an input AM signal.
(1) Note. Amplitude modulation is achieved by varying the
amplitude of a carrier over a continuum of values in
accordance with a modulating signal.
(2) Note. This subclass includes amplitude modulation
demodulators, per se. See the SEARCH CLASS note below for
combinations with the subject matter of this subclass.
SEE OR SEARCH THIS CLASS, SUBCLASS:
311 for a pulse demodulator.
315 for frequency modulation demodulator.
345 for a phase modulation demodulator.
SEE OR SEARCH CLASS:
455, Telecommunications, 130 for a telecommunication
receiver utilizing an amplitude modulation demodulator as a
subcombination thereof.
Subclass:
348
Having plural demodulation outputs:
This subclass is indented under subclass 347. Subject matter
where there are more than one output signal which as
undergone demodulation, one of which must have undergone
amplitude demodulation.
Subclass:
349
Having specific distortion, noise or other interference
prevention, reduction or compensation:
This subclass is indented under subclass 347. Subject matter
including the neutralization of an undesirable characteristic
of an amplitude modulation demodulator or its signals.
SEE OR SEARCH THIS CLASS, SUBCLASS:
318 for distortion or noise control in a frequency
modulation demodulator.
SEE OR SEARCH CLASS:
455, Telecommunications, 63 and 501+ for noise control in a
telecommunication system with separated transmitter and
receiver, and subclasses 296+ for receiver noise or
interference control, particularly subclasses 309 and 312.
Subclass:
350
Automatic amplitude stabilization or control:
This subclass is indented under subclass 349. Subject matter
in which undesirable fluctuations in the magnitude of a
demodulator signal are eliminated or reduced.
Subclass:
351
Nonlinearity reduction or compensation:
This subclass is indented under subclass 349. Subject matter
where an undesirable nonlinear characteristic of a
demodulator, its components or its signals is neutralized.
Subclass:
352
Temperature compensation:
This subclass is indented under subclass 349. Subject matter
in which undesirable effects of ambient temperature on a
demodulator are diminished.
Subclass:
353
Noise reduction or compensation:
This subclass is indented under subclass 349. Subject matter
in which undesired signal components superimposed upon a
desired demodulator signal are attenuated.
(1) Note. In some instances, noise is generated due to an
inherent characteristic of a demodulator circuit component.
Subclass:
354
Including microwave or distributed parameter structure:
This subclass is indented under subclass 347. Subject matter
utilizing a structure or device which is peculiar to
microwave frequencies or which has resistance, inductance or
capacitance not concentrated in lumped circuit elements.
SEE OR SEARCH THIS CLASS, SUBCLASS:
322 for similar structure in a frequency modulation
demodulator.
Subclass:
355
With electron discharge device:
This subclass is indented under subclass 354. Subject matter
utilizing a device which has electrical current flow between
two spaced electrodes in a gas, vapor or vacuum.
(1) Note. This might include, for example, vacuum or gas
tubes such as diodes, triodes or pentodes.
(2) Note. Additional control electrodes may be present.
Subclass:
356
Suppressed carrier double sideband type:
This subclass is indented under subclass 347. Subject matter
where the input AM signal has had the carrier attenuated and
both sidebands are present.
SEE OR SEARCH CLASS:
455, Telecommunications, subclass 46 for a suppressed
carrier system having separated transmitter and receiver and
subclass 202 for a suppressed carrier- type receiver.
Subclass:
357
Single or vestigial sideband type:
This subclass is indented under subclass 347. Subject matter
where the input AM signal has less than two complete
sidebands present.
(1) Note. The carrier may or may not be present in the
input signal.
SEE OR SEARCH CLASS:
455, Telecommunications, subclass 47 for a single or
vestigial sideband system with separated transmitter and
receiver and subclasses 203 or 204 for a single sideband or
vestigial sideband-type receiver, respectively.
Subclass:
358
Input signal combined with local oscillator or carrier
frequency signal (e.g., synchronous demodulator):
This subclass is indented under subclass 347. Subject matter
where the modulated signal input to the demodulator interacts
therein with oscillations from a secondary source.
(1) Note. The secondary oscillations may be internally
generated or externally supplied and may be at a frequency
other than that of the modulated input signal's carrier.
(2) Note. A synchronous demodulator uses a local carrier
frequency signal synchronized with the carrier of the
modulated input signal to cancel out the modulated input
signal's carrier.
SEE OR SEARCH THIS CLASS, SUBCLASS:
302 for similar structure in a frequency shift keying or
minimum shift keying demodulator.
306 for similar structure in a phase shift keying or
quadrature amplitude demodulator.
323 for similar structure in a frequency modulation
demodulator.
346 for similar structure in a phase modulation
demodulator.
SEE OR SEARCH CLASS:
455, Telecommunications, 255 for generic local oscillator
frequency control in a receiver.
Subclass:
359
Input signal applied directly to local oscillator:
This subclass is indented under subclass 358. Subject matter
where the input AM signal interacts directly with the local
secondary source of oscillations.
Subclass:
360
Including phase or frequency locked loop:
This subclass is indented under subclass 358. Subject matter
in which frequency stability is provided to the secondary
source of oscillations by a phase or frequency locked loop.
SEE OR SEARCH CLASS:
331, Oscillators, 1 for phase or frequency locked loops, per
se.
455, Telecommunications, subclass 260 for phase locked loop
or frequency synthesizer in a receiver.
Subclass:
361
Including sampling, gating or switching:
This subclass is indented under subclass 358. Subject matter
which additionally includes signal processing of an
interruptive or discrete nature.
(1) Note. This may include, for example, chopping of the
modulated input signal.
Subclass:
362
With three or more terminal discrete semiconductor device:
This subclass is indented under subclass 361. Subject matter
utilizing an electrical device with three external connection
points where the constituent portions of the device are
constructed from solid material having room temperature
conductivity between that of a conductor and an insulator and
which conductivity is typically modified through the addition
of small amounts of dopant.
(1) Note. This might include, for example, semiconductor
diodes or transistors of diverse type.
Subclass:
363
Input signal split into plural signals:
This subclass is indented under subclass 347. Subject matter
in which the modulated signal input to the demodulator is
separated into a plurality of closely analogous or identical
representations.
SEE OR SEARCH THIS CLASS, SUBCLASS:
327 for input signal splitting in a frequency modulation
demodulator.
Subclass:
364
Including three or more terminal discrete semiconductor
device:
This subclass is indented under subclass 363. Subject matter
utilizing an electrical device with three external connection
points where the constituent portions of the device are
constructed from solid material having room temperature
conductivity between that of a conductor and an insulator and
which conductivity is typically modified through the addition
of small amounts of dopant.
(1) Note. This might include, for example, semiconductor
diodes or transistors of diverse type.
Subclass:
365
Including diode demodulator device:
This subclass is indented under subclass 363. Subject matter
utilizing a unidirectional electrical element as
demodulator.
(1) Note. The diodes of this subclass may be either
semiconductor or tube type.
Subclass:
366
Plural diodes:
This subclass is indented under subclass 365. Subject matter
having a plurality of demodulating unidirectional electrical
elements.
Subclass:
367
Including regenerative feedback in nonoscillating
demodulator:
This subclass is indented under subclass 347. Subject matter
in which an AM demodulator, not requiring a supplemental
source of oscillations to achieve demodulation, positively
feeds back a portion of its output to provide signal
enhancement.
Subclass:
368
Electron discharge demodulator device having more than two
electrodes (e.g., triode, tetrode, etc.):
This subclass is indented under subclass 347. Subject matter
in which an AM demodulator utilizes a device which has
electrical current flow between two spaced electrodes in a
gas, vapor or vacuum and which current flow is controlled by
an additional electrode.
Subclass:
369
Including three or more terminal discrete semiconductor
demodulator device:
This subclass is indented under subclass 347. Subject matter
in which the AM demodulator utilizes an electrical device
with three external connection points where the constituent
portions of the device are constructed from solid material
having room temperature conductivity between that of a
conductor and an insulator and which conductivity is
typically modified through the addition of small amounts of
dopant.
(1) Note. This might include, for example, semiconductor
diodes or transistors of diverse type.
Subclass:
370
Including diode demodulator device:
This subclass is indented under subclass 347. Subject matter
where the AM demodulator incorporates a unidirectional
electrical element.
(1) Note. The diodes of this subclass may be either
semiconductor or tube type.
Subclass:
371
Coherer type demodulator:
This subclass is indented under subclass 347. Subject matter
where the demodulating element includes conductors loosely
resting against each other in imperfect conducting contact,
the conductors being of such a material and shape that
passage of a high frequency current therethrough modifies the
conducting contact.
(1) Note. Usually the demodulating element is formed from
loosely packed metallic granules, whose contact resistance
decreases upon passage of a high frequency current
therethrough. However, the contact resistance may increase
under these conditions to constitute an anticoherer, which is
also included here.
(2) Note. The coherer often includes structure, namely, a
decoherer, for breaking the coherence established by the high
frequency current.
SEE OR SEARCH CLASS:
178, Telegraphy, subclass 117 for an alternating current
teles:graphic system utilizing a coherer.
257, Active Solid-State Devices (e.g., Transistors,
Solid-State Diodes), subclass 43 for active solid-state type
coherers.
338, Electrical Resistors, subclass 1 for coherer-type
resistors, per se.
Subclass:
372
MISCELLANEOUS:
This subclass is indented under the class definition.
Subject matter not provided for in any previous subclass.
Information Products Division -- Contacts
Questions regarding this report should be directed to:
U.S. Patent and Trademark Office
Information Products Division
PK3- Suite 441
Washington, DC 20231
tel: (703) 306-2600
FAX: (703) 306-2737
email: oeip@uspto.gov
Last Modified: 6 October 2000