US PATENT SUBCLASS 324 / 76.41
.~.~ Frequency comparison, (e.g., heterodyne, etc.)

Current as of: June, 1999
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324 /   HD   ELECTRICITY: MEASURING AND TESTING

76.11  DF  MEASURING, TESTING, OR SENSING ELECTRICITY, PER SE {46}
76.39  DF  .~ Frequency of cyclic current or voltage (e.g., cyclic counting etc.) {6}
76.41.~.~ Frequency comparison, (e.g., heterodyne, etc.) {4}
76.42  DF  .~.~.~> With sampler
76.43  DF  .~.~.~> With plural mixers
76.44  DF  .~.~.~> With filtering {2}
76.47  DF  .~.~.~> Digital output {1}

DEFINITION

Classification: 324/76.41

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

(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, 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,

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

30+, for tuners combined with resonant indicators.

455, Telecommunications, for this subject matter in combination with a radio receiving system, particularly

145+, for panoramic receivers.