Code sequence synchronization system for spread spectrum communication receiver

• US 4,423,517 A
• Filed: 01/19/1981
• Issued: 12/27/1983
• Est. Priority Date: 01/21/1980
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Kanno, Masashi, Danno, Tsuneo, Murata, Eiichiro
• Primary Examiner(s): Safourek, Benedict V.
• Assistant Examiner(s): Chin, Stephen
• Application Number:
  US06/226,472
• Time in Patent Office: 1,072 Days
• Field of Search: 375/1, 375/93, 375/115, 375/116, 375/118, 375/25, 370/107, 370/108, 343/5 PN, 343/100 CL
• US Class Current: 375/150
• CPC Class Codes: H04B 1/7075 with code phase acquisition
• CPC Class Codes: H04B 1/709 Correlator structure

Abstract

A synchronization system for a spread spectrum communication receiver generates a receiving code sequence which is identical to an input code sequence and then varies the timing of the receiving code sequence using a correlator until the two code sequences are correlated.

Claims

1. A spread spectrum receiver for receiving a spread spectrum signal, comprising:

a correlating means for correlating a pseudonoise code with a received signal spectrum signal so as to collapse the spread spectrum of the received signal;

a demodulating means coupled to said correlating means for demodulating the thus collapsed received signal;

a detecting means coupled to said demodulating means for detecting synchronization between said pseudonoise code and said demodulated collapsed received signal;

a clock pulse generating means coupled to said detecting means for generating a clock pulse which is the same as that of said received signal when said pseudonoise code and said demodulated received signal are synchronized with each other, and which has a clock rate which has a small offset from that of said demodulated received signal so as to search the synchronization when said pseudonoise code and said demodulated received signal are out of synchronization with each other; and

a pseudonoise code generating means coupled to said detecting means and also coupled to and driven by said clock pulse generating means for generating said pseudonoise code so as to restore the relative position between said pseudonoise code and a pseudonoise code of said demodulated received signal at least before a time that the synchronization has been detected by said detecting means;

wherein said detecting means comprises;

a first filter for extracting a noise component from the output of said demodulating means in order to ensure the detecting of said synchronization;

and wherein said detecting means further comprises;

a second filter for extracting a pilot signal component from the output of said demodulating means, and a comparator for comparing said noise component with said pilot signal component in order to ensure the detecting of said synchronization.

2. A spread spectrum receiver according to claim 1, wherein said demodulating means comprises an FM discriminator for obtaining a base band signal.