Method and apparatus for the reception and demodulation of spread spectrum radio signals

• US 5,166,952 A
• Filed: 05/24/1990
• Issued: 11/24/1992
• Est. Priority Date: 05/24/1990
• Status: Expired due to Term

• Current Assignee: Taggert Hodings LLC (Intellectual Ventures LLC)
• Original Assignee: Cylink Corp. (Thales SA)
• Inventors: Avidor, Dan, Omura, Jimmy K., Heising, Mark
• Primary Examiner(s): SWANN, TOD R
• Application Number:
  US07/528,020
• Time in Patent Office: 915 Days
• Field of Search: 380/33, 380/34, 380/49, 375/1, 375/89, 375/38, 375/48, 455/59, 455/103, 370/120
• US Class Current: 375/149
• CPC Class Codes: H04B 1/70757 with increased resolution, i.e. higher than half a chip H04B1/70758 takes precedence
• CPC Class Codes: H04B 1/7077 Multi-step acquisition, e.g. multi-dwell, coarse-fine or validation
• CPC Class Codes: H04B 1/7085 using a code tracking loop, e.g. a delay-locked loop

Abstract

A spread spectrum receiver with filters matched to transmitter chip codes are implemented in digital circuits along with a digital circuit for acquisition and tracking of the arrival times of the chip codes. The digital circuit implementations are used for the noncoherent demodulation of pulse position spread spectrum modulation signals where the pulse is a carrier modulator by a chip code and for the noncoherent demodulation of multiple chip code modulation signals where each information symbol is represented by one of several chip codes modulating a carrier.

Claims

1. A spread spectrum receiver for demodulating a spread spectrum signal having a concatenated sequence of shortened chip codes, extended chip codes and normal chip codes, comprising:

means for receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

first means coupled to said receiving means for repetitively sampling the in-phase signal, thereby generating a plurality of in-phase samples;

second means coupled to said receiving means for repetitively sampling the quadrature-phase signal, thereby generating a plurality of quadrature-phase samples;

correlator means coupled to said first sampling means and to said second sampling means and responsive to a normal correlator chip code for correlating the plurality of in-phase samples with the normal correlator chip code to generate an in-phase correlation signal, for correlating the plurality of quadrature-phase samples with the normal correlator chip code to generate a quadrature-phase correlation signal, and for generating an output correlation signal from a square root of a sum of the square of the in-phase correlation signal plus the square of the quadrature-phase correlation signal;

means coupled to said correlator means for acquiring and tracking the output correlation signal for generating a reference timing signal; and

means coupled to said correlator means and to said acquiring and tracking means and responsive to comparing the output correlation signal with the reference timing signal, for detecting the timing of the output correlation signal with respect to the reference timing signal, thereby detecting shortened chip codes, extended chip codes and normal chip codes of the spread spectrum signal.

2. The spread spectrum receiver as set forth in claim 1 wherein:

said first sampling means samples the in-phase signal at twice a chip rate of the spread spectrum signal to generate the plurality of in-phase samples; and

said second sampling means samples the quadrature-phase signal at twice a chip rate of the spread spectrum signal to generate the plurality of quadrature-phase samples.

3. The spread spectrum receiver as set forth in claim 1 wherein:

said first sampling means samples the in-phase signal at n greater than 1 times a chip rate of the spread spectrum signal to generate the plurality of in-phase samples; and

said second sampling means samples the quadrature-phase signal at n greater than 1 time a chip rate of the spread spectrum signal to generate the plurality of quadrature-phase samples.

51. The spread spectrum receiver as in any one of claims 1, 18, 19, 31, 34, 35, 45, 49, or 50, further comprising:

an adding means, responsive to an in-phase correlation signal and to an quadrature-phase correlation signal, for adding the square of each at least one in-phase correlation signal and the square of each at least one quadrature-phase correlation signal; and

a means for generating a square root of the sum of the squares of each at least one in-phase correlation signal and of each at least one quadrature-phase correlation signal as an output correlation signal.

4. A spread spectrum receiver for demodulating a spread spectrum signal comprising:

means for receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

first means coupled to said receiving means for repetitively sampling the in-phase signal at twice a chip rate of the spread spectrum signal and separating the two samples per chip of the spread spectrum signal into a first sequence of in-phase samples and a second sequence of in-phase samples;

second means coupled to said receiving means for repetitively sampling the quadrature phase signal at twice the chip rate of the spread spectrum signal and separating the two samples per chip of the spread spectrum signal into a first sequence of quadrature-phase samples and a second sequence of quadrature-phase samples;

first correlating means coupled to said first sampling means and responsive to when the first sequence of in-phase samples are identical to a first plurality of 1-bit code chips for generating a first correlation signal;

second correlating means coupled to said first sampling means and responsive to when the second sequence of in-phase samples are identical to the first plurality of 1-bit code chips for generating a second correlation signal;

third correlating means coupled to said second sampling means and responsive to when the first sequence of quadrature phase samples are identical to a second plurality of 1-bit code chips for generating a third correlation signal;

fourth correlating means coupled to said second sampling means and responsive to when the second sequence of quadrature phase samples are identical to the second plurality of 1-bit code chips for generating a fourth correlation signal; and

means coupled to said first correlating means, said second correlating means, said third correlating means, and said fourth correlating means for squaring the first correlating signal, for squaring the second correlation signal, for squaring the third correlation signal, and for squaring the fourth correlation signal, and adding the squared first, second, third, and fourth correlation signals.

5. A spread spectrum receiver for demodulating a spread spectrum signal comprising:

means for receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase;

first means for repetitively sampling the in-phase signal at n greater than 1 times a chip rate of the spread spectrum signal and separating the n samples per chip of the spread spectrum signal into a plurality of sequences of in-phase samples;

second means for repetitively sampling the quadrature-phase signal at n greater than 1times a chip rate of the spread spectrum signal and separating the n samples per chip of the spread spectrum signal into a plurality of sequences of quadrature-phase samples;

a first plurality of correlating means responsive to when the plurality of sequences of in-phase samples are identical to a first plurality of 1-bit code chips for generating a first plurality of correlation signals;

a second plurality of correlating means responsive to when the plurality of sequences of quadrature-phase samples are identical to a second plurality of 1-bit code chips for generating a second plurality of correlation signals; and

means responsive to the first plurality of correlation signals for squaring each of the first plurality of correlation signals, responsive to the second plurality of correlation signals for squaring each of the second plurality of correlation signals, and for adding each of the squared first plurality of correlation signals and the squared second plurality of correlation signals.

6. A method using a spread spectrum receiver for demodulating a spread spectrum signal comprising the steps of:

generating an in-phase signal and a quadrature-phase signal from the spread spectrum signal;

sampling repetitively the in-phase signal with at least twice a chip rate of the spread spectrum signal;

adding, for a plurality of chips of the in-phase signal, at least two samples per chip to generate a plurality of in-phase samples;

comparing each of the plurality of in-phase samples to a chip code to generate a first plurality of comparison signals;

adding the first plurality of in-phase samples to a chip code to generate a first plurality of comparison signals;

adding the first plurality of comparison signals to generate an in-phase correlation signal;

sampling repetitively the quadrature-phase signal with at least twice a chip rate of the spread spectrum signal;

adding, for a plurality of chips of the quadrature-phase signal, at least two samples per chip to generate a plurality of quadrature-phase samples;

comparing each of the plurality of quadrature-phase samples to a chip code to generate a second plurality of comparison signals;

adding the second plurality of comparison signals to generate a quadrature-phase correlation signal;

squaring the in-phase correlation signal and squaring the quadrature-phase correlation signal; and

adding the squared in-phase correlation signal to the squared quadrature-phase correlation signal.

7. A method using a spread spectrum radio receiver for demodulating a spread spectrum signal comprising:

receiving the spread spectrum signal with the spread spectrum radio receiver;

generating an in-phase signal and a quadrature-phase signal from the spread spectrum signal;

sampling repetitively the in-phase signal at twice a chip rate of the spread spectrum signal;

separating the two samples per chip of the in-phase signal into a first sequence of in-phase samples and a second sequence of in-phase samples;

sampling repetitively the quadrature phase signal at twice the chip rate of the spread spectrum signal;

separating the two samples per chip of the quadrature-phase signal into a first sequence of quadrature phase samples and a second sequence of quadrature phase samples;

generating a first correlation signal from the first sequence of in-phase samples;

generating a second correlation signal from the second sequence of in-phase samples;

generating a third correlation signal from the first sequence of quadrature-phase samples;

generating a fourth correlation signal from the second sequence of quadrature-phase samples;

squaring the first correlating signal;

squaring the second correlation signal;

squaring the third correlation signal;

squaring the fourth correlation signal; and

adding the squared first, second, third, and fourth correlation signals.

8. A method using a spread spectrum radio receiver for demodulating a spread spectrum signal comprising:

receiving the spread spectrum signal;

generating an in-phase signal and a quadrature-phase signal from the spread spectrum signal;

sampling repetitively the in-phase signal at n greater than 1 times a chip rate of the spread spectrum signal;

separating the n samples per chip of the in-phase signal into a plurality of sequences of in-phase samples;

sampling repetitively the quadrature phase signal at n greater than 1 times a chip rate of the spread spectrum signal;

separating the n samples per chip of the quadrature-phase signal into a plurality of sequences of quadrature phase samples;

generating a first plurality of correlation signals when the plurality of sequences of in-phase samples are identical to a first plurality of 1-bit code chips;

generating a second plurality of correlation signals when the plurality of sequences of quadrature phase samples are identical to a second plurality of 1-bit code chips; and

squaring each of the first plurality of correlation signals;

squaring each of the second plurality of correlation signals; and

adding each of the squared first plurality of correlation squared second plurality of correlation signals.

9. A spread spectrum receiver for demodulating a spread spectrum signal having a sequence of concatenated first and second chip codes, comprising:

receiver means for receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

first means for repetitively sampling the in-phase signal, thereby generating a plurality of in-phase samples;

second means for repetitively sampling the quadrature-phase signal, thereby generating a plurality of quadrature-phase samples;

first correlator means for correlating the in-phase samples and the quadrature-phase samples with a first correlator chip code to generate a first correlation signal;

second correlator means for correlating the in-phase samples and the quadrature-phase samples with a second correlator chip code, thereby generating a second correlation signal;

means for acquiring and tracking the first correlation signal and the second correlation signal, thereby generating a reference signal; and

means responsive to the timing from the reference signal for detecting the first correlation signal and responsive to the timing from the reference signal for detecting the second correlation signal.

10. The spread spectrum receiver as set forth in claim 9 wherein:

said first sampling mean samples the in-phase signal with at least twice a chip rate of the spread spectrum signal and adds, for a plurality of chips of the in-phase signal, at least two samples per chip to generate the plurality of in-phase samples; and

said second sampling mean samples the quadrature-phase signal with at least twice a chip rate of the spread spectrum signal and adds, for a plurality of chips of the quadrature-phase signal, at least two samples per chip to generate the plurality of quadrature-phase samples.

11. The spread spectrum receiver as set forth in claim 9 wherein:

said first sampling means samples the in-phase signal at n greater than 1 times a chip rate of the spread spectrum signal to generate the plurality of in-phase samples; and

said second sampling means samples the quadrature-phase signal at n greater than 1 times a chip rate of the spread spectrum signal to generate the plurality of quadrature-phase samples.

12. A spread spectrum receiver for demodulating a spread spectrum signal having a sequence of concatenated first, second, third and fourth chip codes, comprising:

receiver means for receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

first means for repetitively sampling the in-phase signal, thereby generating a plurality of in-phase samples;

second means for repetitively sampling the quadrature-phase signal, thereby generating plurality of quadrature-phase samples,

first correlator means for correlating the in-phase samples and the quadrature-phase samples with a first correlator chip code, thereby generating a first correlation signal;

second correlator means for correlating the in-phase samples and the quadrature phase samples with a second correlator chip code, thereby generating a second correlation signal;

third correlator means for correlating the in-phase samples and the quadrature-phase samples with a third correlator chip code, thereby generating a third correlation signal;

fourth correlator means for correlating the in-phase samples and the quadrature-phase samples with a fourth correlator chip code, thereby generating a fourth correlation signal;

means for acquiring and tracking the first correlation signal, the second correlation signal, the third correlation signal and the fourth correlation signal, thereby generating a reference signal; and

means responsive to the reference signal for detecting the first correlation signal, the second correlation signal, the third correlation signal and the fourth correlation signal, respectively, and for outputting a first data symbol, a second data symbol, a third data symbol or a fourth data symbol, corresponding to the first, second, third or fourth correlation signal having a greatest value, respectively.

13. The spread spectrum receiver as set forth in claim 12 wherein:

said first sampling means samples the in-phase signal at twice a chip rate of the spread spectrum signal to generate the plurality of in-phase samples; and

said second sampling means samples the quadrature-phase signal at twice a chip rate of the spread spectrum signal to generate the plurality of quadrature-phase samples.

14. The spread spectrum receiver as set forth in claim 12 wherein:

said first sampling means samples the in-phase signal at n greater than 1 times a chip rate of the spread spectrum signal to generate the plurality of in-phase samples; and

said second sampling means samples the quadrature-signal at n greater than 1 times a chip rate of the spread spectrum signal to generate the plurality of quadrature-phase samples.

15. A spread spectrum receiver for demodulating a spread spectrum signal having a concatenated sequence of a plurality of chip codes, comprising:

receiver means for receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

first means for repetitively sampling the in-phase signal, thereby generating a plurality of in-phase samples;

second means for repetitively sampling the quadrature-phase signal, thereby generating plurality of quadrature-phase samples,

correlator means for correlating the in-phase samples and the quadrature-phase samples with a plurality of correlator chip codes, respectively, thereby generating a plurality of correlation signals, respectively;

acquiring and tracking means responsive to the plurality of correlation signals for generating a reference signal; and

means responsive to the reference signal, for detecting the plurality of correlation signals and outputting one of a plurality of data symbols, corresponding to the correlation signal having a greatest value, respectively.

16. The spread spectrum receiver as set forth in claim 15 wherein:

said first sampling means samples the in-phase signal at twice a chip rate of the spread spectrum signal to generate the plurality of in-phase samples; and

said second sampling means samples the quadrature-phase signal at twice a chip rate of the spread spectrum signal to generate the plurality of quadrature-phase samples.

17. The spread spectrum receiver as set forth in claim 15 wherein:

said first sampling means samples the in-phase signal at n greater than 1 times a chip rate of the spread spectrum signal to generate the plurality of in-phase samples; and

said second sampling means samples the quadrature-phase signal at n greater than 1 times a chip rate of the spread spectrum signal to generate the plurality of quadrature-phase samples.

18. A spread spectrum receiver for demodulating a spread spectrum signal having a sequence of concatenated first and second chip codes, comprising:

receiver means for receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

first means for repetitively sampling the in-phase signal at twice a chip rate of the spread spectrum signal and for generating, from first and second samples per chip of the in-phase signal, a first plurality of in-phase samples and a second plurality of in-phase samples, respectively;

second means for repetitively sampling the quadrature-phase signal at twice a chip rate of the spread spectrum signal and for generating, from first and second samples per chip of the quadrature-phase signal, a first plurality of quadrature-phase samples and a second plurality of quadrature-phase samples, respectively;

first correlator means for correlating the first plurality of in-phase samples of the first plurality of quadrature-phase samples with a first correlation chip code, for generating a first in-phase correlation signal and a first quadrature-phase correlation signal, respectively, and for generating a first output correlation signal from a square root of a sum of the square of the first in-phase correlation signal plus the square of the first quadrature-phase correlation signal;

second correlator means for correlating the second plurality of in-phase samples and the second plurality of quadrature-phase samples with the first correlator chip code, for generating a second in-phase correlation signal and a second quadrature-phase correlation signal, respectively, and for generating a second output correlation signal from a square root of a sum of the square of the second in-phase correlation signal plus the square of the second quadrature-phase correlation signal;

third correlator means for correlating the first plurality of in-phase samples and the first plurality of quadrature of in-phase samples with a second correlator chip code, for generating a third in-phase correlation signal and a third quadrature-phase correlation signal, respectively, and for generating a third output correlation signal from a square root of a sum of the square of the third in-phase correlation signal plus the square of the third quadrature-phase correlation signal;

fourth correlator means for correlating the second plurality of in-phase samples and the second plurality of quadrature-phase samples with the second correlator chip code, for generating a fourth in-phase correlation signal and a fourth quadrature-phase correlation signal, respectively, and for generating a fourth output correlation signal from a square root of a sum of the square of the fourth in-phase correlation signal plus the square of the fourth quadrature-phase correlating signal;

means for acquiring and tracking the first output correlation signal, the second output correlation signal, the third output correlation signal, and the fourth output correlation signal, for generating a reference signal; and

means responsive to the reference signal for detecting the first output correlation signal, the second output correlation signal, the third output correlation signal and the fourth output correlation signal, respectively, and responsive to the the first or second output correlation signal having a greatest value for outputting a first data symbol, and responsive to the third or fourth output correlation signal having a greater value for outputting a second data symbol.

19. A spread spectrum receiver for demodulating a spread spectrum signal having a sequence of concatenated first and second chip codes, comprising:

receiver means for receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

first means for repetitively sampling the in-phase signal at n greater than 1 times a chip rate of the spread spectrum signal for generating, from n samples per chip of the in-phase signal, n pluralities of in-phase samples, respectively;

second means for repetitively sampling the quadrature-phase signal at n greater than 1 time a chip rate of the spread spectrum signal for generating, from n samples per chip of the quadrature-phase signal, n pluralities of quadrature-phase samples, respectively;

first correlator means for correlating the n pluralities of in-phase samples and the n pluralities of quadrature-phase samples with a first correlator chip code, for generating a first in-phase correlation signal and a first quadrature-phase correlation signal, respectively, and for generating a first output correlation signal from a square root of a sum of the square of the first in-phase correlation signal plus the square of the first quadrature-phase correlation signal;

second correlator means for correlating the n pluralities of in-phase samples and the n pluralities of quadrature-phase samples with a second correlator chip code, for generating a second in-phase correlation signal and a second quadrature-phase correlation signal, respectively, and for generating a second output correlation signal from a square root of a sum of the square of the second in-phase correlation signal plus the square of the second quadrature-phase correlation signal;

means for acquiring and tracking the first output correlation signal and the second output correlation signal, for generating a reference signal; and

means responsive to the reference signal for detecting the first output correlation signal and the second output correlation signal, respectively, responsive to detecting the first output correlation signal having a greater value for outputting a first data symbol, and responsive to detecting the second output correlation signal, having the greatest value for outputting a second data symbol, respectively.

20. A method using a spread spectrum receiver for demodulating a spread spectrum signal having a sequence of concatenated first and second chip codes, comprising the steps, using said spread spectrum receiver, of:

receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

sampling repetitively the in-phase signal to generate a plurality of in-phase samples;

sampling repetitively the quadrature-phase signal to generate a plurality of quadrature-phase samples;

correlating noncoherently the in-phase samples and the quadrature-phase sample with a first correlator chip code for generating a first in-phase correlation signal and a first quadrature-phase correlation signal, respectively, and for generating a first output correlation signal from a square root of a sum of the square of the first in-phase correlation signal plus the square of the first quadrature-phase correlation signal;

correlating noncoherently the in-phase samples and the quadrature phase samples with a second correlator chip code for generating a second in-phase correlation signal and a second quadrature-phase correlation signal, respectively, and for generating a second output correlation signal from a square root of a sum of the square of the second in-phase correlation signal plus the square of the second quadrature-phase correlation signal;

acquiring and tracking the first output correlation signal and the second output correlation signal to generate a reference signal;

detecting the first output correlation signal and the second output correlation signal using timing from the reference signal;

outputting a first data symbol in response to the first output correlation signal having a greatest value; and

outputting a second data symbol in response to the second output correlation signal having a greatest value.

21. The method as set forth in claim 20 wherein:

said first sampling step samples the in-phase signal at twice a chip rate of the spread spectrum signal to generate the plurality of in-phase samples; and

said second sampling step samples the quadrature-phase signal at twice a chip rate of the spread spectrum signal to generate the plurality of quadrature-phase samples.

22. The method as set forth in claim 20 wherein:

said first sampling step samples the in-phase signal at n greater than 1 times a chip rate of the spread spectrum signal to generate the plurality of in-phase samples; and

said second sampling step samples the quadrature-phase signal at n greater 1 time a chip rate of the spread spectrum signal to generate the plurality of quadrature-phase samples.

52. The method using a spread spectrum receiver as in any one of claims 20, 23, 29, 30, 36, 39, 47, or 48, wherein the steps of generating an output correlation signal include:

summing the square of each at least one in-phase correlation signal and the square of each at least one quadrature-phase correlation signal; and

generating a square root of the sum of the square of each at least one in-phase correlation signal and of each at least one quadrature-phase correlation signal as an output correlation signal.

23. A method using a spread spectrum receiver for demodulating a spread spectrum signal having a sequence of concatenated first, second, third and fourth chip codes, comprising the steps, using said spread spectrum receiver, of:

receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

sampling repetitively the in-phase signal to generate a plurality of in-phase samples;

sampling repetitively the quadrature-phase signal to generate a plurality of quadrature-phase samples;

correlating noncoherently the in-phase samples and the quadrature-phase samples with a first correlator chip code for generating a first in-phase correlation signal and a first quadrature-phase correlation signal, respectively, and for generating a first output correlation signal from a square root of a sum of the square of the first in-phase correlation signal plus the square of the first quadrature-phase correlation signal;

correlating noncoherently the in-phase samples and the quadrature-phase samples with a second correlator chip code for generating a second in-phase correlation signal and a second quadrature-phase correlation signal, respectively, and for generating a second output correlation signal from a square root of a sum of the square of the second in-phase correlation signal plus the square of the second quadrature-phase correlation signal;

correlating noncoherently the in-phase samples and the quadrature-phase samples with a third correlator chip code for generating a third in-phase correlation signal and a third quadrature-phase correlation signal, respectively, and for generating a third output correlation signal from a square root of a sum of the square of the third in-phase correlation signal plus the square of the third quadrature-phase correlation signal;

correlating noncoherently the in-phase samples and the quadrature-phase samples with a fourth correlator chip code for generating a fourth in-phase correlation signal and a fourth quadrature-phase correlation signal, respectively, and for generating a fourth output correlation signal from a square root of a sum of the square of the fourth in-phase correlation signal plus the square of the fourth quadrature-phase correlation signal;

acquiring and tracking the first output correlation signal, the second output correlation signal, the third output correlation signal and the fourth output correlation signal to generate a reference signal; and

detecting the first output correlation signal, the second output correlation signal, the third output correlation signal and the fourth output correlation signal, respectively, and outputting a first data symbol, a second data symbol, a third data symbol or a fourth data symbol corresponding to the first, second, third or fourth output correlation signal having a greatest value, respectively.

24. The method as set forth in claim 23 wherein:

said first sampling step samples the in-phase signal at twice a chip rate of the spread spectrum signal to generate the plurality of in-phase samples; and

said second sampling means samples the quadrature-phase signal at twice a chip rate of the spread spectrum signal to generate the plurality of quadrature-phase

25. The method as set forth in claim 23 wherein:

said first sampling step samples the in-phase signal at n greater than 1 times a chip rate of the spread spectrum signal to generate the plurality of in-phase samples; and

said second sampling step samples the quadrature-phase signal at n greater than 1 times a chip rate of the spread spectrum signal to generate the plurality of quadrature-phase samples.

26. A method using a spread spectrum receiver for demodulating a spread spectrum signal having a sequence of a plurality of chip codes, comprising the steps, using said spread spectrum receiver:

receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

sampling repetitively the in-phase signal to generate a plurality of in-phase samples;

sampling repetitively the quadrature-phase signal to generate a plurality of quadrature-phase samples;

correlating noncoherently the in-phase samples and the quadrature-phase samples with the plurality of correlation chip codes, respectively, to generate a plurality of correlation signals, respectively;

acquiring and tracking the plurality of correlation signals to generate a reference signal; and

detecting the plurality of correlation signals and outputting one of a plurality of data symbols corresponding to the correlation signal having a greatest value, respectively.

27. The method as set forth in claim 26 wherein:

said first sampling step samples the in-phase signal at twice a chip rate of the spread spectrum signal to generate the plurality of in-phase samples; and

said second sampling step samples the quadrature-phase signal at twice a chip rate of the spread spectrum signal to generate the plurality of quadrature-phase samples.

28. The method as set forth in claim 26 wherein:

said first sampling step samples the in-phase signal at n greater than 1 times a chip rate of the spread spectrum signal to generate the plurality of in-phase samples; and

said second sampling step samples the quadrature-phase signal at n greater than 1 times a chip rate of the spread spectrum signal to generate the plurality of quadrature-phase samples.

29. A method using a spread spectrum receiver for demodulating a spread spectrum signal having a sequence of concatenated first and second chip codes, comprising the steps, using said spread spectrum receiver, of:

receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

sampling repetitively the in-phase signal at twice a chip rate of the spread spectrum signal for generating, from first and second samples per chip of the in-phase signal, a first plurality of in-phase samples and a second plurality of in-phase samples, respectively;

sampling repetitively the quadrature-phase signal at twice a chip rate of the spread spectrum signal for generating, from first and second samples per chip of the quadrature-phase signal, a first plurality of quadrature-phase samples and a second plurality of quadrature-phase samples, respectively;

correlating noncoherently the first plurality of in-phase samples and the first plurality of quadrature-phase samples with a first correlator chip code for generating a first in-phase correlation signal and a first quadrature-phase correlation signal respectively, and for generating a first output correlation signal from a square root of a sum of the square of the first in-phase correlation signal plus the square of the first quadrature-phase correlation signal;

correlating the second plurality of in-phase samples and the second plurality of quadrature-phase samples with the first correlator chip code for generating a second in-phase correlation signal and a second quadrature-phase correlation signal, respectively, and for generating a second output correlation signal from a square root of a sum of the square of the second in-phase correlation signal plus the square of the second quadrature-phase correlation signal;

correlating the first plurality of in-phase samples and the first plurality of quadrature-phase samples with a second correlator chip code for generating a third in-phase correlation signal and a third quadrature-phase correlation signal, respectively, and for generating a third output correlation signal from a square root of a sum of the square of the third in-phase correlation signal plus the square of the third quadrature-phase correlation signal;

correlating the second plurality of in-phase samples and the second plurality of quadrature-phase samples with the second correlator chip code for generating a fourth in-phase correlation signal and a fourth quadrature-phase correlation signal, respectively, and for generating a fourth output correlation signal from a square root of a sum of the square of the fourth in-phase correlation signal plus the square of the fourth quadrature-phase correlation signal;

acquiring and tracking the first output correlation signal, the second output correlation signal, the third output correlation signal and the fourth output correlation signal to generate a reference signal; and

detecting the first output correlation signal, the second output correlation signal, the third output correlation signal and the fourth output correlation signal, respectively, outputting, in response to detecting the first or second output correlation signal having a greatest value, a first data symbol, and outputting, in response to detecting the second or third output correlation signal having the greatest value, a second data symbol, respectively.

30. A method using a spread spectrum receiver for demodulating a spread spectrum signal having a sequence of concatenated first and second chip codes, comprising the steps, using said spread spectrum receiver, of:

receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

sampling repetitively the in-phase signal at n greater than 1 times a chip rate of the spread spectrum signal for generating, from the n samples per chip of the in-phase signal, n pluralities of in-phase samples, respectively;

sampling respectively the quadrature-phase signal at n greater than 1 times a chip rate of the spread spectrum signal for generating, from n samples per chip of the quadrature-phase signal, n pluralities of quadrature-phase samples, respectively;

correlating the n pluralities of in-phase samples and the n pluralities of quadrature-phase samples with a first correlator chip code for generating as first in-phase phase correlation signal and a first quadrature-phase correlation signal, respectively, and for generating a first output correlation signal from a square root of a sum of the square of the first in-phase correlation signal plus the square of the first quadrature-phase correlation signal;

correlating the n pluralities of in-phase samples and the n pluralities of quadrature-phase samples with a second correlator chip code for generating a second in-phase correlation signal and a second quadrature-phase correlation signal, respectively, and for generating a second output correlation signal from a square root of a sum of the square of the second in-phase correlation signal plus the square of the second quadrature-phase correlation signal;

acquiring and tracking the first output correlation signal, and the second output correlation signal, to generate a reference signal; and

detecting the first output correlation signal, and the second output correlation signal, and outputting a first data symbol in response to the first output correlation signal having a greatest value, and a second data symbol in response to the second output correlation signal having the greatest value, respectively.

31. A spread spectrum receiver for demodulating a spread spectrum signal having a concatenated sequence of shortened chip codes, extended chip codes and normal chip codes, comprising:

means for receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

first means for sampling the in-phase signal, thereby generating a plurality of in-phase samples;

second means for sampling the quadrature-phase signal, thereby generating a plurality of quadrature-phase samples;

correlator means responsive to a normal correlator chip code for correlating the plurality of in-phase samples with the normal correlator chip code to generate an in-phase correlation signal, for correlating the plurality of quadrature-phase samples with the normal correlator chip code to generate a quadrature-phase correlation signal, and for generating an output correlation signal from a square root of a sum of the square of the in-phase correlation signal plus the square of the quadrature-phase correlation signal;

means for acquiring and tracking the output correlation signal for generating a reference timing signal; and

means responsive to comparing the output correlation signal with the reference timing signal, for detecting the timing of the output correlation signal with respect to the reference timing signal, for decoding the output correlation signal.

32. The spread spectrum receiver as set forth in claim 31 wherein:

said first sampling means samples the in-phase signal at twice a chip rate of the spread spectrum signal to generate the plurality of in-phase samples; and

said second sampling means samples the quadrature-phase signal at twice a chip rate of the spread spectrum signal to generate the plurality of quadrature-phase samples.

33. The spread spectrum receiver as set forth in claim 31 wherein:

said first sampling means samples the in-phase signal at n greater than 1 times a chip rate of the spread spectrum signal to generate the plurality of in-phase samples; and

said second sampling means samples the quadrature-phase signal at n greater than 1 times a chip rate of the spread spectrum signal to generate the plurality of quadrature-phase samples.

34. A method using a spread spectrum receiver for demodulating a spread spectrum signal having a concatenated sequence of shortened chip codes, extended chip codes and normal chip codes, comprising:

means for receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

first means for sampling the in-phase signal at twice a chip rate o the spread spectrum signal for generating, from the two samples per chip of the in-phase signal, a first and a second plurality of in-phase samples;

second means for sampling the quadrature-phase signal at twice a chip rate of the spread spectrum signal for generating, from the two samples per chip of the quadrature-phase signal, a first and second plurality of quadrature-phase samples;

correlator means responsive to a normal chip code for correlating the first and second plurality of in-phase samples with the normal chip code to generate the first and second in-phase correlation signal, respectively, for correlating the first and second plurality of quadrature-phase samples with the normal chip code to generate a first and second quadrature-phase correlation signal, respectively, and for generating an output correlation signal from a square root of a sum of the square of the first in-phase correlation signal, the square of the second in-phase correlation signal, the square of the first quadrature-phase correlation signal, plus the square of the second quadrature-phase correlation signal;

means coupled to said correlator means for acquiring and tracking the output correlation signal, for generating a reference timing signal; and

means coupled to said correlator means, coupled to said acquiring and tracking means, and responsive to comparing the output correlation signal with the reference timing signal, for detecting the timing of the output correlation signal with respect to the reference timing signal, and for decoding the output correlation signal.

35. A method using a spread spectrum receiver for demodulating a spread spectrum signal having a concatenated sequence of shortened chip codes, extended chip codes and normal chip codes, comprising:

means for receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

first means for repetitively sampling the in-phase signal at n greater than 1 times a chip rate of the spread spectrum signal for generating, from n samples per chip of the in-phase signal, n pluralities of in-phase samples;

second means coupled to said receiving means for sampling the quadrature-phase signal at n greater than 1 times a chip rate of the spread spectrum signal for generating, from n samples per chip of the spread spectrum signal, n pluralities of quadrature-phase signals;

correlator means coupled to said first sampling means and said second sampling means and responsive to a normal chip code for correlating the n pluralities of in-phase samples with the normal chip code to generate in-phase correlation signals, for correlating the n pluralities of quadrature-phase samples with the normal chip code to generate quadrature-phase correlation signals, and for generating an output correlation signal from a square root of a sum of the square of each in-phase correlation signal plus the square of each quadrature-phase correlation signal;

means coupled to said correlator means for acquiring and tracking the output correlation signal, for generating a reference timing signal; and

means coupled to said correlator means and said acquiring and tracking means and responsive to comparing the output correlation signal with the reference timing signal, for detecting the timing of the output correlation signal with respect to the reference timing signal, and for decoding the output correlation signal.

36. A method using a spread spectrum receiver for demodulating a spread spectrum signal having a concatenated sequence of shorted chip codes, extended chip codes and normal chip codes, comprising the steps, using said spread spectrum receiver, of:

receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

sampling repetitively the in-phase signal, thereby generating a plurality of in-phase samples;

sampling repetitively the quadrature-phase signal, thereby generating a plurality of quadrature-phase samples;

correlating the plurality of in-phase samples with a normal correlator chip code to generate an in-phase correlation signal;

correlating the plurality of quadrature-phase samples with the normal correlator chip code to generate a quadrature-phase correlation signal;

generating an output correlation signal from a square root of a sum of the square of the in-phase correlation signal plus the square of the quadrature-phase correlation signal;

acquiring and tracking the output correlation signal, for generating a reference timing signal; and

detecting the timing of the output correlation signal with respect to the reference timing signal, for decoding the output correlation signal.

37. The method as set forth in claim 36 wherein:

sampling repetitively the in-phase signal includes sampling the in-phase signal at twice a chip rate of the spread spectrum signal and adding, for a plurality of chips in the in-phase signal, the two samples per chip of the spread spectrum signal to generate the plurality of in-phase samples; and

sampling repetitively the quadrature-phase signal includes sampling the quadrature-phase signal at twice a chip rate of the spread spectrum signal and adding, for a plurality of chips in the quadrature-phase signal, the two samples per chip of the spread spectrum signal to generate the plurality of quadrature-phase samples.

38. The method as set forth in claim 36 wherein:

sampling repetitively the in-phase signal includes sampling the in-phase signal at n greater than 1 times a chip rate of the spread spectrum signal and adding, for a plurality of chips in the in-phase signal, the n samples per chip of the spread spectrum signal to generate the plurality of in-phase samples; and

sampling repetitively the quadrature-phase signal includes sampling the quadrature-phase signal at n greater than 1 times a chip rate of the spread spectrum signal and adding, for a plurality of chips in the quadrature-phase signal, the n samples per chip of the spread spectrum signal to generate the plurality of quadrature-phase samples.

39. A method using a spread spectrum receiver for demodulating a spread spectrum signal having a concatenated sequence of shortened chip codes, extended chip codes and normal chip codes, comprising the steps, using said spread spectrum receiver, of:

receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

sampling repetitively the in-phase signal with at least a chip rate of the spread spectrum signal for generating, from first and second samples per chip of the in-phase signal, a first plurality of in-phase samples and a second plurality of in-phase samples, respectively;

sampling repetitively the quadrature-phase signal with at least twice a chip rate of the spread spectrum signal for generating, from first and second samples per chip of the quadrature-phase signal, a first plurality of quadrature-phase samples and a second plurality of quadrature-phase samples, respectively;

correlating the first plurality of in-phase samples with the normal chip code to generate a first in-phase correlation signal;

correlating the second plurality of in-phase samples with the normal chip code to generate a second in-phase correlation signal;

correlating the first plurality of quadrature-phase samples with the normal chip code to generate a first quadrature-phase correlation signal;

correlating the second plurality of quadrature-phase samples with the normal chip code to generate a second quadrature-phase correlation signal;

generating an output correlation signal from a square root of sum of the square of the first in-phase correlation signal, the square of the second in-phase correlation signal, the square of the first quadrature-phase correlation signal plus the square of the second quadrature-phase correlation signal;

acquiring and tracking the output correlation signal, thereby generating a reference timing signal; and

detecting the timing of the output correlation signal with respect to the reference timing signal, thereby decoding the output correlation signal.

40. A spread spectrum receiver for demodulating a spread spectrum signal comprising:

means for receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

first means coupled to said receiving means for repetitively sampling the in-phase signal at twice a chip rate of the spread spectrum signal to generate a sequence of in-phase samples;

second means coupled to said receiving means for repetitively sampling the quadrature phase signal with at least twice a chip rate of the spread spectrum signal to generate a sequence of quadrature phase samples;

first correlating means coupled to said first sampling means and responsive to when the sequence of in-phase samples is identical to a first plurality of 1-bit code chips for generating a first correlation signal;

second correlating means coupled to said second sampling means and responsive to when the sequence of quadrature-phase samples is identical to with a second plurality of 1-bit code chips for generating a second correlation signal; and

means coupled to said first correlating means and said second correlation means, for squaring the first correlating signal, for squaring the second correlation signal, for adding the squared first and second correlation signals, computing a square root of the sum of the squares.

41. A spread spectrum receiver for demodulating a spread spectrum signal comprising:

means for receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

first means for repetitively sampling the in-phase signal at n greater than 1 times a chip rate of the spread spectrum signal for generating a plurality of in-phase samples;

second means for repetitively sampling the quadrature phase signal at n greater than 1 times a chip rate of the spread spectrum signal for generating a plurality of quadrature phase samples;

first correlating means responsive to when the plurality of in-phase samples correlate with a first plurality of 1-bit code chips for generating a first correlation signal;

second correlating means responsive to when the plurality of quadrature phase samples correlate with a second plurality of 1-bit code chips for generating a second correlation signal; and

means for squaring the first correlation signal, for squaring the second correlation signal, and for adding the squared first correlation signal and the squared second correlation signal, and for computing a square root of the sum of the squares.

42. A method using a spread spectrum receiver for demodulating a spread spectrum signal comprising the steps of:

generating an in-phase signal and a quadrature phase signal from the spread spectrum signal;

sampling repetitively the in-phase signal with at least twice a chip rate of the spread spectrum signal to generate a plurality of in-phase samples;

correlating the plurality of in-phase samples with a chip code to generate a first correlation signal;

sampling the quadrature signal at least twice a chip rate of the spread spectrum signal to generate a plurality of quadrature phase samples;

correlating the plurality of quadrature samples with the chip code to generate a second correlation signal;

squaring the in-phase correlation signal and squaring the quadrature phase correlation signal; and

adding the squared in-phase correlation signal to the squared quadrature phase correlation signal.

43. A method using a spread spectrum receiver for demodulating a spread spectrum signal comprising:

receiving the spread spectrum signal with the spread spectrum receiver;

generating an in-phase signal and a quadrature phase signal from the spread spectrum signal;

sampling repetitively the in-phase signal with at least twice a chip rate of the spread spectrum signal to generate a sequence of in-phase samples;

sampling repetitively the quadrature-phase signal with at least twice a chip rate of the spread spectrum signal to generate a sequence of quadrature-phase samples;

generating a first correlation signal from the sequence of in-phase samples;

generating a second correlation signal from the sequence of quadrature-phase samples;

squaring the first correlation signal;

squaring the second correlation signal; and

adding the squared first correlation signal and the squared second correlation signal.

44. A method using a spread spectrum receiver for demodulating a spread spectrum signal comprising:

receiving the spread spectrum signal;

generating an in-phase signal and a quadrature-phase signal from the spread spectrum signal;

sampling repetitively the in-phase signal at n greater than 1 times a chip rate of the spread spectrum signal to generate a sequence of in-phase samples;

sampling repetitively the quadrature-phase signal at n greater than 1 times a chip rate of the spread spectrum signal to generate a sequence of quadrature phase samples;

generating a first correlation signal when the sequence of in-phase samples correlate with a first chip code;

generating a second correlation signal when the sequence of quadrature-phase samples correlate with a second chip code; and

squaring the first correlation signal;

squaring the second correlation signal; and

adding the squared first correlation signal and the squared second correlation signal.

45. A spread spectrum receiver for demodulating a spread spectrum signal having a sequence of concatenated first and second chip codes, comprising:

receiver means for receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

first means for repetitively sampling the in-phase signal at twice a chip rate of the spread spectrum signal and for generating a plurality of in-phase samples;

second means for repetitively sampling the quadrature-phase signal at twice a chip rate of the spread spectrum signal and for generating a plurality of quadrature-phase samples;

first correlator means for correlating the plurality of in-phase samples and the plurality of quadrature-phase samples with a first correlator chip code, for generating a first in-phase correlation signal and a first quadrature-phase correlation signal, respectively, and for generating a first output correlation signal from a square root of a sum of the square of the first in-phase correlation signal plus the square of the first quadrature-phase correlation signal;

second correlator means for correlating the plurality of in-phase samples and the plurality of quadrature-phase samples with a second correlator signal and a second quadrature-phase correlation signal, respectively, and for generating a second output correlation signal from a square root of a sum of the square of the second in-phase correlation signal plus the square of the second quadrature-phase correlation signal;

means for acquiring and tracking the first output correlation signal and the second output correlation signal, for generating a reference signal; and

means responsive to the reference signal for detecting the first output correlation signal and the second output correlation signal, respectively, and responsive to the first output correlation signal having a greatest value for outputting a first data symbol, and responsive to the second output correlation signal having the greatest value for outputting a second data symbol.

46. A spread spectrum receiver for demodulating a spread spectrum signal having a sequence of concatenated first and second chip codes, comprising:

receiver means for receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

first means for repetitively sampling the in-phase signal at n greater than 1 times a chip rate of the spread spectrum signal for generating a plurality of in-phase samples;

second means for repetitively sampling the quadrature-phase signal at n greater than 1 times a chip rate of the spread spectrum signal for generating a plurality of quadrature-phase samples;

first correlator means for correlating the plurality of in-phase samples and the plurality of quadrature-phase samples with a first correlator chip code, thereby generating a first correlation signal;

second correlator means for correlating the plurality of in-phase samples and the plurality of quadrature-phase samples with a second correlator chip code, thereby generating a second correlation signal;

means for acquiring and tracking the first correlation signal and the second correlation signal, for generating a reference signal; and

means responsive to the reference signal and detecting the first correlation signal and the second correlation signal, respectively, responsive to the first correlation signal having a greatest value for outputting a first data symbol, and responsive to the second correlation signal having the greatest value for outputting a second data symbol, respectively.

47. A method using a spread spectrum receiver for demodulating a spread spectrum signal having a sequence of concatenated first and second chip codes, comprising the steps, using said spread spectrum receiver, of:

receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

sampling repetitively the in-phase signal at twice a chip rate of the spread spectrum signal for generating a plurality of in-phase samples;

sampling repetitively the quadrature-phase signal at twice a chip rate of the spread spectrum signal for generating a plurality of quadrature-phase samples;

correlating noncoherently the plurality of in-phase samples and the plurality of quadrature-phase samples with a first correlator chip code for generating a first in-phase correlation signal and a first quadrature-phase correlation signal, respectively, and for generating a first output correlation signal from a square root of a sum of the square of the first in-phase correlation signal plus the square of the first quadrature-phase correlation signal;

correlating noncoherently the plurality of in-phase samples and the plurality of quadrature-phase samples with a second correlator chip code for generating a second in-phase correlation signal and a second quadrature-phase correlation signal, respectively, and for generating a second output correlation signal from a square root of a sum of the square of the second in-phase correlation signal plus the square of the second quadrature-phase correlation signal;

acquiring and tracking the first output correlation signal and the second output correlation signal, to generate a reference signal; and

detecting the first output correlation signal and the second correlation signal, respectively, and outputting, in response to detecting the first output correlation signal having a greatest value, a first data symbol, and outputting, in response to detecting the second output correlation signal having the greatest value, a second data symbol, respectively.

48. A method using a spread spectrum receiver for demodulating a spread spectrum signal having a sequence of concatenated first and second chip codes, comprising the steps using said spread spectrum receiver of:

receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

sampling repetitively the in-phase signal at n greater than 1 times a chip rate of the spread spectrum signal for generating a plurality of in-phase samples;

sampling repetitively the quadrature-phase signal at n greater than 1 times a chip rate of the spread spectrum signal for generating a plurality of quadrature-phase samples;

correlating noncoherently the plurality of in-phase samples and the plurality of quadrature-phase samples with a first correlator chip code for generating a first in-phase correlation signal and a first quadrature-phase correlation signal, respectively, and for generating to generate a first output correlation signal from a square root of a sum of the square of the first in-phase correlation signal plus the square of the first quadrature-phase correlation signal;

correlating noncoherently the plurality of in-phase samples and the plurality of quadrature-phase samples with a second correlator chip code for generating a second in-phase correlation signal and a second quadrature-phase correlation signal, respectively, and for generating a second output correlation signal from a square root of a sum of the square of the second in-phase correlation signal plus the square of the second quadrature-phase correlation signal;

acquiring and tracking the first output correlation signal and the second output correlation signal, to generate a reference signal; and

detecting the first output correlation signal and the second output correlation signal, outputting in response to the first output correlation signal having a greatest value a first data symbol, and outputting in response detecting to the second output correlation signal having the greatest value a second data symbol, respectively.

49. A spread spectrum receiver for demodulating a spread spectrum signal having a concatenated sequence of shortened chip codes, extended chip codes and normal chip codes, comprising:

means for receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

first means for sampling the in-phase signal at twice a chip rate of the spread spectrum signal for generating a plurality of in-phase samples;

second means for sampling the quadrature-phase signal at twice a chip rate of the spread spectrum signal for generating a plurality of quadrature-phase samples;

correlator means responsive to a normal chip code for correlating the plurality of in-phase samples with the normal chip code to generate an in-phase correlation signal, for correlating the plurality of quadrature-phase samples with the normal chip code to generate a quadrature-phase correlation signal, and for generating an output correlation signal from a square root of a sum of the square of the in-phase correlation signal plus the square of the quadrature-phase correlation signal;

means coupled to said correlator means for acquiring and tracking the output correlation signal, for generating a reference timing signal; and

means coupled to said correlator means, coupled to said acquiring and tracking means, responsive to comparing the output correlation signal with the reference timing signal, for detecting the timing of the output correlation signal with respect to the reference timing signal, and for decoding the output correlation signal.

50. A spread spectrum receiver for demodulating a spread spectrum signal having a concatenated sequence of shortened chip codes, extended chip codes and normal chip codes, comprising:

means for receiving the spread spectrum signal and generating an in-phase signal and a quadrature-phase signal;

first means for sampling the in-phase signal at n greater than 1 times a chip rate of the spread spectrum signal for generating a plurality of in-phase samples;

second means for sampling the quadrature-phase signal at n greater than 1 times a chip rate of the spread spectrum signal for generating a plurality of quadrature-phase samples;

correlator means responsive to a normal chip code for correlating the plurality of in-phase samples with the normal chip code to generate an in-phase correlation signal, for correlating the plurality of quadrature-phase samples with the normal chip code to generate a quadrature-phase correlation signal, and for generating an output correlation signal from a square root of a sum of the square of the in-phase correlation signal plus the square of the quadrature-phase correlation signal;

means coupled to said correlator means for acquiring and tracking the output correlation signal, for generating a reference timing signal; and

means coupled to said correlator means, coupled to said acquiring and tracking means, responsive to comparing the output correlation signal with the reference timing signal, for detecting the timing of the output correlation signal with respect to the reference timing signal, and for decoding the output correlation signal.