Spread-spectrum communication system
AssigneeClarion Co., Ltd.
InventorMasahiro Tsuchiya
Life of this patent
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Abstract
A receiver in a spread-spectrum communication system is adapted to receive a signal which is modulated by a binary code modulated by a binary code or a data, and includes a matched filter which detects a correlation between the received signal and a reference signal modulated by a reference code produced by a code generator. When the received code supplied from the matched filter coincides with or is slightly displaced from the reference code, a pulse is produced from a correlation spike waveform with a relatively large amplitude to extract a desired pulse from the pulse and use it to initialize the reference code generator.
Claims1
A receiver in a spread-spectrum communication system adapted to receive a signal which is modulated by a binary code modulated by a binary code or data, including a surface acoustic wave filter for detecting a correlation between the received signal and a signal modulated by a time-reversed reference binary code 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 said surface acoustic wave filter 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.
Dependencies are inferred from the claim text.