Spread spectrum communication receiver

• US 4,943,975 A
• Filed: 10/07/1988
• Issued: 07/24/1990
• Est. Priority Date: 10/09/1987
• Status: Expired due to Fees

• Current Assignee: Clarion Co., Ltd. (Faurecia SA)
• Original Assignee: Clarion Co., Ltd. (Faurecia SA)
• Inventors: Kurihara, Takao, Mori, Masaharu, Hamatsu, Masahiro
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US07/256,394
• Time in Patent Office: 655 Days
• Field of Search: 375/1, 380/34
• US Class Current: 375/150
• CPC Class Codes: H04B 1/70712 with demodulation by means of convolvers, e.g. of the SAW type SAW convolvers in general G06G7/195
• CPC Class Codes: H04B 1/7093 Matched filter type

Abstract

A spread spectrum communication receiver is disclosed, which is provided with a correlator for correlating a received PN code contained in a received signal with a reference PN code contained in a reference signal generated on the receiver side, the output of which is given to pattern judgment means such as a matched filter, etc., and an operation of the initial synchronization of the two PN codes in the correlator is effected by using a judgment output obtained when the pattern of the output of the correlator is in accordance with a predetermined judgment pattern.

Claims

1. A spread spectrum communication receiver comprising:

correlating means for correlating a received PN code contained in a received signal with a reference PN code contained in a reference signal;

correlation pulse generating means for generating a series of correlation pulses, corresponding to the polarity of a correlation spike outputted by said correlating means;

reference signal generating means for generating said reference signal;

means for generating sampling pulses before and after said correlation pulse in time and extracting a correlation pulse from said series of correlation pulses by using those sampling pulses;

digital phase lock means for holding the synchronization between said received PN code and said reference PN code;

phase control means for controlling the phase of said reference PN code, responding to the output of said digital phase lock means; and

data demodulation means for demodulating said received signal to obtain data by extracting a correlation pulse from said series of correlation pulses by using a window pulse having a time interval between said sampling pulses generated before and after said correlation pulse in time.

2. A spread spectrum communication receiver comprising:

reference PN code generator means for generating a reference PN code;

convolver means for correlating a received PN code contained in a received signal with said reference PN code to generate a correlation spike;

correlation pulse generator means for generating a series of correlation pulses corresponding to the polarity of said correlation spike from said convolver means and having a pattern;

detecting means for detecting coincidence between said pattern of said series of correlation pulses and a predetermined pattern, and for producing a detection signal upon detection of said coincidence;

an up/down counter supplied with a start signal indicative of the start of said reference PN code and supplied with said detection signal from said detecting means, said counter starting counting in one of up and down directions in response to receipt of said start signal, changing the counting direction with respect to an obtained count value in response to receipt of said detection signal, and producing an output pulse when the count value reaches a predetermined value; and

phase control means responsive to said output pulse of said counter for producing a control signal for controlling the phase of said reference PN code.

3. The spread spectrum communication receiver according to claim 2, wherein said up/down counter is initialized with an offset count value which is a function of a delay time from said correlation spike to a point in time at which said detecting means detects said coincidence, and wherein said counting in response to said start signal starts from said offset count value.

4. The spread spectrum communication receiver according to claim 2, wherein said code generator means includes means for generating said start signal, and includes means responsive to said control signal from said phase control means for controlling the phase of said reference PN code.

5. A spread spectrum communication receiver comprising:

reference PN code generator means for generating a reference PN code;

convolver means for correlating a received PN code contained in a received signal with said reference PN code to generate a correlation spike;

correlation pulse generator means for generating a series of correlation pulses corresponding to the polarity of said correlation spike from said convolver means;

means for generating an early sampling pulse prior to and a later sampling pulse after a point in time at which a correlation pulse should be generated by said pulse generator means when the received PN code has a predetermined relationship with respect to said reference PN code;

detecting means supplied with said series of correlation pulses and responsive to said sampling pulses for detecting a time deviation from said point in time of a correlation pulse generated by said pulse generating means; and

phase control means responsive to detection of said time deviated correlation pulse for generating a phase control signal to control the phase of said reference PN code.

6. The spread spectrum communication receiver according to claim 5, wherein said means for detecting a time deviated correlation pulse includes a counter for counting the number of correlation pulses sampled in response to a plurality of said early sampling pulses as a result of a time deviation representing a time advance and for counting the number of correlation pulses sampled in response to a plurality of said later sampling pulses as a result of a time deviation representing a time delay, said counter generating a deviation signal indicative of the amount of advance or delay time deviation based on its count value and supplying said deviation signal to said phase control means, said phase control means generating said phase control signal in response to said deviation signal.

7. The spread spectrum communication receiver according to claim 5, wherein said code generator means is responsive to said phase control signal for controlling the phase of said reference PN code.

8. A spread spectrum communication receiver, comprising:

reference PN code generator means for generating a reference PN code;

convolver means for correlating a received PN code contained in a received signal with said reference PN code to produce a correlation spike;

correlation pulse generator means for generating a series of correlation pulses corresponding to the polarity of said correlation spike from said convolver means;

means for generating an early sampling pulse prior to and a later sampling pulse after a point in time at which a correlation pulse should be generated by said pulse generator means when the received PN code has a predetermined relationship with respect to said reference PN code;

window pulse means for generating a window pulse based on said sampling pulses and having a predetermined time width; and

data demodulating means responsive to said window pulse for extracting a correlation pulse from said series of correlation pulses and demodulating data therefrom.

9. The spread spectrum communication receiver according to claim 8, wherein said window pulse begins when said early sampling pulse begins and terminates when said later sampling pulse terminates.

10. The spread spectrum communication receiver according to claim 8, including matching means for detecting a relative match between said demodulated data and a predetermined pattern in order to detect the start timing of information data present in said demodulated data and to produce a detection output for an exterior circuit, said matching means being weighted according to said predetermined pattern.

11. A spread spectrum communication receiver comprising:

reference PN code generator means for generating a reference PN code;

convolver means for correlating a received PN code contained in a received signal with said reference PN code to produce a correlation spike;

correlation pulse generator means for generating a series of correlation pulses corresponding to the polarity of said correlation spike from said convolver means and having a pattern;

first detecting means for detecting coincidence between the pattern of said series of correlation pulses and a pattern whose bits are all "1" or "0" and for producing a detection output in response to detection of said coincidence;

initial synchronizing means responsive to said detection output for controlling the phase of said reference PN code to establish initial synchronization between said received and reference PN codes;

data demodulating means for extracting a desired pulse from said series of correlation pulses and for demodulating data therefrom; and

second detecting means for detecting coincidence between said demodulated data and one of a predetermined Barker code and its phase-inverted pattern and for producing a detecting signal representing the start timing of information data contained in said demodulated data.