Spread-spectrum communication system

Claim 1

A receiver in a spread-spectrum communication system adapted to receive a signal which is .Iadd.first .Iaddend.modulated by .[.a.]. .Iadd.binary data and thereafter by a .Iaddend.binary code .[.modulated by a binary code or data.]., and including a surface acoustic wave convolver for detecting a correlation between the received signal and a signal modulated by a .[.time-reversed.]. reference binary code .Iadd.in the form of a time-reversed replica .Iaddend.of said binary code, said receiver comprising: first means for producing a correlation spike pulse from a correlation waveform signal with a relatively large amplitude when said binary code in said received signal supplied .[.from.]. .Iadd.to .Iaddend.said surface acoustic wave convolver coincides with or has a small displacement from said reference binary code; second means for selectively extracting a desired correlation spike pulse from said correlation spike pulses from said first means and producing a reset pulse therefrom; and a code generator for producing said reference binary code and initialized by said reset pulse, wherein said first means include: an amplifier for amplifying said correlation waveform signal; an envelope detector for extracting a signal having an envelope waveform in an output signal from said amplifier; a threshold detector for comparing the amplitude of said envelope waveform signal with a predetermined threshold and generating a pulse responsive to the result of the comparison; and wherein said second means include: a wave shaping circuit for shaping said pulse from said threshold detector into a pulse with a predetermined width; said reference binary code being synchronized by a synchronizing pulse; a gate pulse generator for generating a gate pulse from said pulse synchronizing said reference binary code; and a gate circuit responsive to said gate pulse to selectively extract said pulse supplied from said wave shaping circuit. .Iadd.