Patent No. 3641445 Frequency analyzer
Patent No. 3641445 Frequency analyzer (Green, Feb 8, 1972) Abstract A frequency analyzer is provided wherein real-time, narrow band-pass filters having large dynamic range are synthesized for each frequency. Each filter consists of a local clock driven synchronous detector followed by a simple integrating circuit. Large dynamic range is achieved through the use of a two-state switching device as the synchronous detector. Since the output of the synchronous detector depends on the phase relationship between the input signal and the local clock, two phase-quadrature filters are provided for each frequency. The output from the filter pair is processed in a manner that yields a signal whose amplitude is independent of the input signal-local clock phase relationship. Notes: BACKGROUND OF THE INVENTION This invention relates generally to a frequency discriminator and more particularly to a high resolution, real-time freque