Method and apparatus for the modulation of spread spectrum radio signals

• US 5,157,686 A
• Filed: 06/24/1991
• Issued: 10/20/1992
• 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:
  US07/720,142
• Time in Patent Office: 484 Days
• Field of Search: 375/1, 375/38, 375/48, 380/34, 380/42, 380/49, 380/50, 370/18, 370/17, 370/69.1, 465/59, 341/55, 341/59, 341/67, 341/70, 341/82, 341/83, 341/182
• US Class Current: 375/146
• 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 modulator for use on a data bit sequence, comprising:

means for generating a Manchester bit sequence from the data bit sequence by encoding each data bit of the data bit sequence with Manchester encoding bits;

means coupled to said generating means and responsive to a first bit and a second bit in the Manchester bit sequence for substituting a normal chip code for the second bit when the first bit and the second bit are identical, for substituting a shortened chip code for the second bit when the first bit and the second bit are a "1" bit followed by a "0" bit, and for substituting an extended chip code for the second bit when the first bit and the second bit are a "0" bit followed by a "1" bit, thereby generating a sequence of concatenated codes;

means coupled to said substituting means for pseudorandomly inverting the sequence of concatenated codes; and

means coupled to said inverting means for modulating a carrier signal with the pseudorandomly inverted sequence of concatenated codes.

2. A spread spectrum modulator for use on a data bit sequence, comprising:

means for generating a Manchester bit sequence from the data bit sequence by encoding each data bit of the data bit sequence with Manchester encoding bits;

means coupled to said generating means and responsive to a first bit and a second bit in the Manchester bit sequence for substituting a normal chip code for the second bit when the first bit and the second bit are identical, for substituting a shortened chip code for the second bit when the first bit and the second bit are a "1" bit followed by a "0" bit, and for substituting an extended chip code for the second bit when the first bit and the second bit are a "0" bit followed by a "1" bit, thereby generating a sequence of concatenated codes; and

means coupled to said substituting means and responsive to the sequence of concatenated codes for modulating a carrier signal.

3. A spread spectrum modulator for use on a data bit sequence, comprising:

means responsive to each bit of the data bit sequence for substituting a first chip code for each bit of the data bit sequence when each bit is a "1" bit, and for substituting a second chip code for each bit of the data bit sequence when each bit is a "0" bit, thereby generating a sequence of concatenated first and second chip codes;

means coupled to said substituting means for pseudorandomly inverting the sequence of concatenated first and second chip codes; and

means coupled to said inverting means and responsive to the inverted sequence of concatenated first and second chip codes for modulating a carrier signal.

4. A spread spectrum modulator for use on a data symbol sequence, comprising:

means responsive to each symbol of the data symbol sequence for substituting a first chip code for each symbol of the data symbol sequence when each symbol is a first data symbol, and for substituting a second chip code for each symbol of the data symbol sequence when each symbol is a second data symbol, for substituting a third chip code for each symbol of the data symbol sequence when each symbol is a third data symbol, and for substituting a fourth chip code for each symbol of the data symbol sequence when each symbol is a fourth data symbol, thereby generating a sequence of concatenated first, second, third and fourth chip codes; and

means coupled to said substituting means and responsive to the sequence of concatenated first, second, third and fourth chip codes, for modulating a carrier signal.

5. A spread spectrum modulator for use on a data symbol sequence, comprising:

means responsive to each symbol of the data symbol sequence for substituting a first chip code for each symbol of the data symbol sequence when each symbol is a first data symbol, for substituting a second chip code for each symbol of the data symbol sequence when each symbol is a second data symbol, for substituting a third chip code for each symbol of the data symbol sequence when each symbol is a third data symbol, and for substituting a fourth chip code for each symbol of the data symbol sequence when each symbol is a fourth data symbol, thereby generating a sequence of concatenated first, second, third and fourth chip codes;

means coupled to said substituting means for pseudorandomly inverting the sequence of concatenated first, second, third and fourth chip codes; and

means coupled to said inverting means and responsive to the inverted sequence of concatenated first, second, third and fourth chip codes, for modulating a carrier signal.

6. A spread spectrum modulator for use on a data symbol sequence, comprising:

means responsive to each symbol of the data symbol sequence for substituting a corresponding chip code for each corresponding data symbol of the data symbol sequence, thereby generating a sequence of chip codes;

means coupled to said substituting means for pseudorandomly inverting the sequence of chip codes; and

means coupled to said inverting means and responsive to each inverted chip code for modulating a carrier signal.

7. A method using a processor for modulating a data bit sequence with spread spectrum, comprising the steps, using the processor, of:

generating a Manchester bit sequence from the data bit sequence by encoding each data bit of the data bit sequence with Manchester encoding bits;

substituting, responsive to a first bit and a second bit in the Manchester bit sequence, a normal chip code for the second bit when the first and second bits are identical;

substituting, responsive to the first bit and the second bit in the Manchester bit sequence, a shortened chip code for the second bit when the first and second bits are a "1" bit followed by a "0" bit;

substituting, responsive to the first bit and the second bit in the Manchester bit sequence, an extended chip code for the second bit when the first and second bits are a "0" bit followed by a "1" bit;

generating from the normal chip code, shortened chip code and extended chip code, a sequence of concatenated codes; and

modulating a carrier signal with the sequence of concatenated codes.

8. The method as set forth on claim 7 further comprising the steps of pseudorandomly inverting the sequence of concatenated codes and modulating the carrier with the inverted sequence of concatenated codes.

9. A method using a processor for modulating a data bit sequence with spread spectrum, comprising the steps, using the processor, of:

substituting a first chip code for each bit of the data bit sequence when each bit is a "1" bit;

substituting a second chip code for each bit of the data bit sequence when each bit is a "0" bit;

generating a sequence of concatenated first and second chip codes;

pseudorandomly inverting the sequence of concatenated first and second chip codes for generating a pseudorandomly inverted sequence; and

modulating a carrier signal when the pseudorandomly inverted sequence.

10. A method using a processor for modulating a data symbol sequence with spread spectrum, comprising the steps, using the processor, of:

substituting a first chip code for each symbol of the data symbol sequence when each symbol is a first data symbol;

substituting a second chip code for each symbol of the data symbol sequence when each symbol is a second data symbol;

substituting a third chip code for each symbol of the data symbol sequence when each symbol is a third data symbol;

substituting a fourth chip code for each symbol of the data symbol sequence when each symbol is a fourth data symbol;

generating a sequence of concatenated first, second, third and fourth chip codes; and

modulating a carrier signal with the sequence of concatenated first, second, third, and fourth chip codes.

11. A method using a processor for modulating a data symbol sequence with spread spectrum, comprising the steps, using the processor, of:

substituting a first chip code for each symbol of the data symbol sequence when each symbol is a first data symbol;

substituting a second chip code for each symbol of the data symbol sequence when each symbol is a second data symbol;

substituting a third chip code for each symbol of the data symbol sequence when each symbol is a third data symbol;

substituting a fourth chip code for each symbol of the data symbol sequence when each symbol is a fourth data symbol;

generating a sequence of concatenated first, second, third and fourth chip codes;

pseudorandomly inverting the sequence of concatenated first second, third and fourth chip codes for generating a pseudorandomly inverted sequence; and

modulating a carrier signal with the pseudorandomly inverted sequence.

12. A method using a processor for modulating a data symbol sequence with spread spectrum, comprising the steps, using the processor, of:

substituting a corresponding chip code for each corresponding data symbol of the data symbol sequence;

generating a sequence of chip codes;

pseudorandomly inverting the sequence of chip codes for generating a pseudorandomly inverted sequence; and

modulating a carrier signal with the pseudorandomly inverted sequence.