(under subclass 401) Subject matter wherein a device is used in which an energy source alters the value of a parameter of an energy storage element for frequency conversion.
SEE OR SEARCH CLASS
324, Electricity: Measuring and Testing,
76.41, for electric current frequency measuring systems, utilizing heterodyne means; and subclass 85 for electric current phase measuring systems utilizing frequency conversion.
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems,
113+, for miscellaneous frequency conversion circuits.
329, Demodulators,
323+, 346 or 358+ for frequency, phase or amplitude modulation demodulators combining the incoming signal with a second locally generated signal. 330, Amplifiers,
4.5+, for parametric amplifiers wherein the output signal waveform is an amplified replica of the input signal waveform and linearly related thereto.
331, Oscillators,
37+, for beat frequency oscillators.
332, Modulators,
117+, or 144+ for frequency or phase modulators, and particularly subclasses 140 and 142+ for variable reactance tubes in a frequency modulator.
359, Optics: Systems (Including Communication) and Elements, appropriate subclasses for optical systems, per se and
326+, for optical or quasi - optical parametric frequency converters.
363, Electric Power Conversion Systems,
1+, for frequency conversion without intermediate conversion to d.c. in cascaded or combined diverse conversion systems.
455, Telecommunications, 313+, for frequency converters adapted for use in modulated carrier wave receivers and wherein an incoming signal-modulated carrier wave is combined or mixed with a local carrier wave to produce an intermediate frequency signal of value lower than that of the incoming modulated carrier wave.
