Spread spectrum communication device

• US 5,048,052 A
• Filed: 02/02/1990
• Issued: 09/10/1991
• Est. Priority Date: 02/07/1989
• Status: Expired due to Fees

• Current Assignee: Clarion Co., Ltd. (Faurecia SA)
• Original Assignee: Clarion Co., Ltd. (Faurecia SA)
• Inventors: Mori, Masaharu, Minagawa, Shoichi, Hamatsu, Masahiro
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US07/475,185
• Time in Patent Office: 585 Days
• Field of Search: 375/1, 375/111, 375/114-120, 380/48, 380/46, 380/47
• US Class Current: 375/151
• CPC Class Codes: H04B 1/70718 with asynchronous demodulation, i.e. not requiring code synchronisation
• CPC Class Codes: H04B 1/709 Correlator structure

Abstract

The present invention is a spread spectrum communications system where the plural pseudonoise codes are switched such that one pseudonoise code represents binary "1" and another pseudonoise code represents binary "0" of the binary data to be transmitted. Further, in the receiver, a reference pseudonoise code is generated which is asynchronous with respect to the carrier and with respect to the pseudonoise codes of the transmitter. The reference pseudonoise code is used in a convolver to reproduce the transmitted information signal.

Claims

1. A spread spectrum communication device comprising:

a transmitter which includes;

spread-modulating means including a plurality of pseudo-noise code generators outputting different code patterns and a gate which, in response to information data, selects and outputs one of said code patterns from a respective one of said pseudo-noise code generators, said transmitter transmitting a spread signal which has a carrier frequency and includes said selected code pattern; and

a receiver which includes;

a reference pseudo-noise code generator generating a reference pseudo-noise code which is asynchronous to said carrier frequency and said selected code pattern from said transmitter and which is inverted in time with respect to the code pattern of one of said pseudo-noise code generators of said transmitter;

a surface acoustic wave convolver to which is applied said reference pseudo-noise code and the spread signal from said transmitter,

a waveform shaper which shapes a waveform of a correlation peak train outputted by said convolver; and

demodulator means for reproducing said information data in response to pulses of the shaped waveform from said waveform shaper.

2. A spread spectrum communication device according to claim 1, wherein said pseudo-noise code generators in said transmitter include first and second pseudo-noise code generators, and wherein said gate is a steering gate which, in response to first and second states of said information data, selects and outputs the code patterns respectively outputted by said first and said second pseudo-nose code generators.

3. A spread spectrum communication device according to claim 2 wherein said steering gate includes first and second NAND circuits, a NOT circuit and a NOR circuit.

4. A spread spectrum communication device comprising:

a transmitter which includes;

spread-modulating means including a plurality of pseudo-noise code generators outputting different code patterns and a gate which, in response to information data, selects and outputs one of said code patterns from a respective one of said pseudo-noise code generators, said transmitter transmitting a spread signal which has a carrier frequency and includes said selected code pattern; and

a receiver which includes;

a plurality of reference pseudo-noise code generators, each of which generates a reference pseudo-noise code which is asynchronous to said carrier frequency and said selected code pattern from said transmitter and which is inverted in time with respect to the code pattern of a respective one of said pseudo-noise code generators of said transmitter;

a plurality of surface acoustic wave convolvers which each have applied thereto a respective said reference pseudo-noise code and the spread signal from said transmitter;

a plurality of waveform shapers which each shape a waveform of a respective correlation peak train outputted by a respective one of said convolvers; and

comparing demodulating means for reproducing said information data by comparing the shaped waveforms from said plurality of waveform shapers.

5. A spread spectrum communication device according to claim 4, wherein said pseudo-noise code generators in said transmitter include first and second pseudo-noise code generators, and wherein said gate is a steering gate which, in response to first and second states of said information data, selects and outputs the code patterns respectively outputted by said first and said second pseudo-noise code generators.

6. A spread spectrum communication device according to claim 5, wherein said steering gate includes first and second NAND circuits, a NOT circuit and a NOR circuit.

7. A spread spectrum communication device comprising:

a transmitter which includes;

spread-modulating means including a plurality of pseudo-noise code generators outputting different code patterns and a gate which, in response to information data, selects and outputs one of said code patterns from a respective one of said pseudo-noise code generators, said transmitter transmitting a spread signal which has a carrier frequency and includes said selected code pattern; and

a receiver which includes;

a plurality of reference pseudo-noise code generators each generating a reference pseudo-noise code which is asynchronous to said carrier frequency and said selected code pattern from said transmitter and which is inverted in time with respect to the code pattern of a respective one of said pseudo-noise code generators of said transmitter;

a surface acoustic wave convolver to which is applied a selected one of said reference pseudo-noise codes and the spread signal from said transmitter;

a waveform shaper which shapes a waveform of a correlation peak train outputted by said convolver;

control means for effecting selection of said selected one of said plurality of reference pseudo-noise codes in response to the shaped waveform from said waveform shaper; and

comparing demodulating means for reproducing said information data from the shaped waveform.

8. A spread spectrum communication device according to claim 7 wherein said pseudo-noise code generators in said receiver include first and second pseudo-noise code generators and a steering gate which, in response to an output of said control means, selects and outputs one of said reference pseudo-noise codes which is inverted in time with respect to the code pattern in the spread signal and which is outputted by a respective one of said first and said second pseudo-noise code generators.

9. A spread spectrum communication device according to claim 8 wherein said steering gate includes first and second NAND circuits, a NOT circuit and a NOR circuit.

10. A spread spectrum communication device according to claim 7 wherein said comparing demodulating means reproduces and information data by demodulating the shaped waveform from said waveform shaper.

11. A spread spectrum communication device according to claim 7 wherein said comparing demodulating means includes a pulse width enlarging circuit which outputs a signal to a first toggle flipflop.

12. A spread spectrum communication device according to claim 11 wherein said control means includes a second toggle flipflop which receives said signal from said pulse width enlarging circuit.

13. A spread spectrum communication device according to claim 7, wherein said pseudo-noise code generators in said transmitter include first and second pseudo-noise code generators, and wherein said gate is a steering gate which, in response to first and second states of said information data, selects and outputs the code patterns respectively outputted by said first and second pseudo-noise code generators.

14. A spread spectrum communication device according to claim 13, wherein said steering gate includes first and second NAND circuits, a NOT circuit and a NOR circuit.

15. A spread spectrum communication device according to claim 7, wherein said control means includes a toggle flipflop.

16. A spread spectrum communication apparatus, comprising:

a transmitter which includes first pseudo-noise code generator means for producing first and second pseudo-noise codes which are different, selecting means for respectively selecting said first and second pseudo-noise codes when an information signal respectively has first and second states, and means for generating a spread signal which is transmitted by said transmitter and which has a carrier frequency and includes the pseudo-noise code selected by said selecting means; and

a receiver which includes second pseudo-noise code generator means for generating a third pseudo-noise code which is asynchronous to said carrier frequency and said selected pseudo-noise code and which is the time inverse of a respective one of said first and second pseudo-noise codes, a convolver to which is applied said third pseudo-noise code and the spread signal received from said transmitter, and means responsive to an output of said convolver for reproducing said information signal.

17. A spread spectrum communication apparatus according to claim 16, wherein said second pseudo-noise code generator means generates a fourth pseudo-noise code which is asynchronous to said carrier frequency and said selected pseudo-noise code, said third and fourth pseudo-noise codes respectively being time inverses of said first and second pseudo-noise codes, and including a further convolver to which is applied said fourth pseudo-noise code and the spread signal received from said transmitter, said means for reproducing said information signal being responsive to an output of said further convolver.

18. A spread spectrum communication apparatus according to claim 16, wherein said second pseudo-noise code generator means generates fourth and fifth pseudo-noise codes which are asynchronous to said carrier frequency and said selected pseudo-noise code, said fourth and fifth pseudo-noise codes respectively being time inverses of said first and second pseudo-noise codes, and including control means cooperable with said means which reproduces said information signal for causing said second pseudo-noise code generator means of said receiver to respectively select said fourth and fifth pseudo-noise codes to be said third pseudo-noise code when said information signal reproduced in said receiver is respectively in said two states thereof.