Detection of angular modulated electromagnetic signals

Claim 2

A signal processing circuit for detecting spread spectrum radio frequency signals at a predetermined output frequency comprising: a source of spread spectrum radio frequency signals; means for splitting said signals into first and second part signals on first and second paths, respectively; first local oscillator means for generating a radio frequency output signal of frequency equaling the center frequency of said spread spectrum signals; second local oscillator means for generating a radio frequency output signal of frequency one-half said predetermined output signal center frequency; first single sideband modulator means connected with said first and second local oscillator means for generating from said first and second local oscillator means outputs, a summation frequency output signal; second single sideband modulator means connected with said first and second local oscillator means for generating from said first and second local oscillator means outputs, a difference frequency output signal; first mixer means for mixing said first part signal and said summation frequency signal to form a first mixer output signal; second mixer means for mixing said second part signal and said difference frequency signal to form a second mixer output signal; and third mixer means for mixing said first and second mixer output signals to form a resultant output signal at said predetermined center frequency.

Claim 3

The processing circuit of claim 1 further including first and second wide bandpass filters located between said first and third and between said second and third mixer means respectively and tuned, respectively, to the sum frequency of the two input signals of said second mixer means and to the difference frequency of the two input signals of said second mixer means.

Claim 4

The signal processing circuit of claim 2 further including angular modulation detection means coupled with said resultant output of said third mixer means.

Claim 7

The method of claim 4 further including the steps of: filtering said upper intermediate signal using a wide bandpass centered at the difference of said upper sideband component and said spread spectrum input signal prior to said blending step; and suppressing all but a wide bandpass component centered at the difference of said lower sideband component and said spread spectrum input signal from said lower intermediate signal prior to said blending step.

Claim 8

Signal bandwidth compression apparatus for detecting spread spectrum angular modulation signals of center frequency f i comprising: means for generating first and second local oscillator signals of radio frequencies f i and one-half f o , respectively; single sideband combining means for combining said first and second local oscillator signals into an upper sideband combination signal and a lower sideband combination signal; wide bandpass input filtering means for removing signals outside a predetermined band from the input signal of said apparatus; first mixing means for mixing said upper sideband combination signal with said spread spectrum filtered input signal to form a first internal signal; first wide bandpass filtering means for extracting from said first internal signal a sideband component having a response centered at the sum of said upper bandpass and said spread spectrum signals to form a filtered first internal signal; second mixing means for mixing said lower sideband combination signal with said spread spectrum input signal to form a second interval signal; second wide bandpass filtering means for extracting from said second internal signal a wideband component having a response centered at the difference of said lower bandpass and said spread spectrum signals to form a filtered second internal signal; third mixing means for mixing said filtered first and second internal signals; narrow bandpass filtering means centered at the sum of said filtered first and second internal signals for extracting an f o centered component therefrom; and amplitude modulation detection means for detecting the amplitude modulation component of said f o centered component.

Claim 9

Signal bandwidth compression apparatus for detecting spread spectrum angular modulation signals of center frequency f i comprising: means for generating first and second local oscillator signals of radio frequencies f i and one-half f o , respectively; single sideband combining means for combining said first and second local oscillator signals into an upper sideband combination signal and a lower sideband combination signal; wide bandpass input filtering means for removing signals outside a predetermined band from the input signal of said apparatus; first mixing means for mixing said upper sideband combination signal with said spread spectrum filtered input signal to form a first internal signal; first wide bandpass filtering means for extracting from said first internal signal a sideband component having a response centered at the sum of said upper bandpass and said spread spectrum signals to form a filtered first internal signal; second mixing means for mixing said lower sideband combination signal with said spread spectrum input signal to form a second interval signal; second wide bandpass filtering means for extracting from said second internal signal a wideband component having a response centered at the difference of said lower bandpass and said spread spectrum signals to form a filtered second internal signal; third mixing means for mixing said filtered first and second internal signals; narrow bandpass filtering means centered at the sum of said filtered first and second internal signals for extracting an f o centered component therefrom; and amplitude modulation detection means for detecting the amplitude modulation component of said f o centered component.