US PATENT SUBCLASS 327 / 40
.~.~ Comparison between plural inputs

Current as of: June, 1999
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327 /   HD   MISCELLANEOUS ACTIVE ELECTRICAL NONLINEAR DEVICES, CIRCUITS, AND SYSTEMS

1  DF  SPECIFIC SIGNAL DISCRIMINATING (E.G., COMPARING, SELECTING, ETC.) WITHOUT SUBSEQUENT CONTROL {11}
39  DF  .~ By frequency {3}
40.~.~ Comparison between plural inputs {3}
41  DF  .~.~.~> With synchronous detection
42  DF  .~.~.~> Fixed frequency reference signal
43  DF  .~.~.~> With logic or bistable circuit

DEFINITION

Classification: 327/40

Comparison between plural inputs:

(under subclass 39) Subject matter wherein the output signal is a function of the differences among two or more input signal frequencies.

(1) Note. Systems wherein the claimed subject matter includes apparatus which responds only when a noninformation bearing input signal is in synchronism with a control signal locally generated (synchronous detectors) and which are not claimed as an integral part of a more comprehensive system will be classified herein. Detectors producing an output which is a result of demodulation of a carrier having previously been modulated by an intelligence waveform which varies arbitrarily will not be classified here. See SEARCH CLASS, below.

SEE OR SEARCH THIS CLASS, SUBCLASS:

3, for phase comparison between plural input signals.

SEE OR SEARCH CLASS

329, Demodulators, appropriate subclasses for a circuit having an output which is a result of demodulation of a carrier having previously been frequency modulated by an intelligence waveform.

455, Telecommunications, 130+, for mixers or converters utilized in a superheterodyne receiver (commonly referred to as a first detector), and subclasses 313+ for combining frequencies in a receiver to produce a beat frequency.