Digital compressive receiver
First Claim
1. A compressive surveillance receiver, comprising:
- frequency synthesizing means for generating a composite local oscillator signal including N discrete signal uniformly spaced in frequency;
first means for generating a repetitive digitally coded sequence having N bits;
second means responsive to said first means for providing N outputs, said coded sequence appearing at each of said N outputs in a delayed series whereby said coded sequence is extant at each successive output of said series delayed by one bit as compared to the preceding output in said series;
third means for modulating each of said N discrete local oscillator signals by said coded sequence extant at a corresponding one of said N outputs of said second means to provide N modulated outputs;
mixer means responsive to received input signals in a band of surveillance and to said third means outputs for converting said received input signals to signals in the intermediate frequency domain;
and means comprising a matched filter responsive to said intermediate frequency signals for correlating all coded sequence modulated intermediate frequency signals extant at the output of said mixer and corresponding to said received input signals to provide output pulses at times which are a function of the corresponding delay of the coded sequence modulated onto each corresponding local oscillator signal generated by said frequency synthesizer.
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Accused Products
Abstract
A compressive receiver for developing a series of time-based identifying pulses corresponding to discrete received signals having various frequencies within a predetermined band of surveillance. A multiple local oscillator function is included, effectively dividing the predetermined band of interest into small frequency increments, each of these local oscillator signals being coded by a pseudo-random coded sequence (bi-phase code) of maximal length. Each frequency increment thus developed is coded by this sequence delayed by one bit duration as compared to that applied to the local oscillator frequency immediately preceding it. A mixer receiving input signals in the band of interest, and also the multiple local oscillator signals thus generated and coded, has its output processed by a passive correlator which provides pulses at times determined by the frequencies extant in the input signal.
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Citations
12 Claims
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1. A compressive surveillance receiver, comprising:
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frequency synthesizing means for generating a composite local oscillator signal including N discrete signal uniformly spaced in frequency; first means for generating a repetitive digitally coded sequence having N bits; second means responsive to said first means for providing N outputs, said coded sequence appearing at each of said N outputs in a delayed series whereby said coded sequence is extant at each successive output of said series delayed by one bit as compared to the preceding output in said series; third means for modulating each of said N discrete local oscillator signals by said coded sequence extant at a corresponding one of said N outputs of said second means to provide N modulated outputs; mixer means responsive to received input signals in a band of surveillance and to said third means outputs for converting said received input signals to signals in the intermediate frequency domain; and means comprising a matched filter responsive to said intermediate frequency signals for correlating all coded sequence modulated intermediate frequency signals extant at the output of said mixer and corresponding to said received input signals to provide output pulses at times which are a function of the corresponding delay of the coded sequence modulated onto each corresponding local oscillator signal generated by said frequency synthesizer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification