System and method for communicating data using constant amplitude equalized waveform

• US 20060215786A1
• Filed: 03/24/2005
• Published: 09/28/2006
• Est. Priority Date: 03/24/2005
• Status: Active Grant

• Current Assignee: Harris Global Communications, Inc. (L3Harris Technologies, Inc.)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Nieto, John W., Furman, William N., Wadsworth, Michael A.
• Granted Patent: US 7,508,884 B2
• Time in Patent Office: Days
• US Class Current: 375/305
• CPC Class Codes: H04L 27/2014 in which the phase changes in a piecewise linear manner during each symbol period, e.g. minimum shift keying, fast frequency shift keying H04L27/201 takes precedence
• CPC Class Codes: H04L 27/2017 in which the phase changes are non-linear, e.g. generalized and Gaussian minimum shift keying, tamed frequency modulation H04L27/201 takes precedence

Abstract

A system communicates data and includes an encoder for encoding communications data with a forward error correction code. A data randomizer randomizes the communications data with a random bit sequence and a combining circuit combines the communications data with known symbols into frames. A modulator maps the communications data into minimum shift keying or Gaussian minimum shift keying (MSK or GMSK) symbols based on a specific mapping algorithm to form a communications signal having an MSK or GMSK waveform over which the communications data can be transmitted.

Claims

1. A system for communicating data, which comprises:

an encoder for encoding communications data using a forward error correction code;

a data randomizer that randomizes the communications data with a random bit sequence;

a combining circuit for combining the communications data with known symbols into frames; and

a modulator for mapping the communications data from the combining circuit into minimum shift keying or Gaussian minimum shift keying (MSK or GMSK) symbols based on a specific mapping algorithm to form a communications signal having a MSK or GMSK waveform over which the communications data can be transmitted.

2. A system according to claim 1 and further comprising a block interleaver for interleaving the communications data after encoding.

3. A system according to claim 1 wherein said data randomizer is operative for extracting communications data after said block interleaver is full.

4. A system according to claim 1 wherein said combining circuit is operative for combining the communications data with unknown symbols into frames.

5. A system according to claim 1, which further comprises a receiver having filter that is matched to a main pulse of the MSK or GMSK waveform for receiving the communications signal over which the communications data has been transmitted.

6. A system according to claim 1, which further comprises a receiver having a block or symbol equalizer and a clamping circuit for receiving and equalizing the communications signal and clamping communications data symbols to a purely real symbol (+/−

1) or a purely imaginary symbol (+/−

j).

7. A system according to claim 1, which further comprises a receiver having a block or symbol equalizer and a clamping circuit for receiving and equalizing the communications signal and clamping communications data symbols based on a substantially fixed rotation mapping.

8. A system according to claim 1, wherein said block or symbol equalizer and clamping circuit are operative for clamping odd or even communications data symbols to real symbols and clamping respective even or odd communications data symbols to imaginary symbols.

9. A system according to claim 1, wherein said encoder is operative for encoding communications data with a rate ½

convolutional code.

10. A system for communicating data, which comprises:

a transmitter for transmitting a communications signal that carries communications data, and including an encoder for encoding the communications data with a forward error correction code, a data randomizer that randomizes the communications data with a random bit sequence, a combining circuit for combining the communications data with known symbols into frames, and a modulator for mapping the communications data from the combining circuit into minimum shift keying or Gaussian minimum shift keying (MSK or GMSK) symbols based on a specific mapping algorithm to form a communications signal having a MSK or GMSK waveform over which the communications data can be transmitted; and

a receiver for receiving the communications signal from the transmitter, and including a filter that is matched to a main pulse of the MSK or GMSK waveform and a block or symbol equalizer for equalizing the communications signal.

11. A system according to claim 10, wherein said receiver comprises a block or symbol equalizer and a clamping circuit operative for clamping communications data symbols to a real symbol (+/−

1) or an imaginary symbol (+/−

j).

12. A system according to claim 10, wherein said block or symbol equalizer and clamping circuit are operative for clamping odd or even communications data symbols to real symbols and clamping respective even or odd communications data symbols to imaginary symbols.

13. A system according to claim 10, wherein said transmitter further comprises a block interleaver for interleaving the communications data after encoding.

14. A system according to claim 10, wherein said data randomizer is operative for extracting communications data after said block interleaver is full.

15. A system according to claim 10, wherein said combining circuit is operative for combining the communications data with unknown symbols into frames.

16. A system according to claim 10, wherein said encoder is operative for encoding communications data with a rate ½

convolutional code.

17. A system according to claim 10, which further comprises a receiver having a block or symbol equalizer and a clamping circuit for receiving and equalizing the communications signal and clamping communications data symbols based on a substantially fixed rotation mapping.

18. A method for communicating data, which comprises:

encoding communications data with a forward error correction code;

randomizing the communications data with a random bit sequence;

combining the communications data with known symbols into frames; and

mapping the communications data into minimum shift keying or Gaussian minimum shift keying (MSK or GMSK) symbols after combining based on a specific mapping algorithm to form a communications signal having a MSK or GMSK waveform over which the communications data can be transmitted.

19. A method according to claim 18, which further comprises interleaving the communications data.

20. A method according to claim 19, which further comprises extracting communications data for randomizing after interleaver is full.

21. A method according to claim 19, which further comprises block interleaving the communications data.

22. A method according to claim 18, which further comprises receiving the communications signal within a filter of a receiver that is matched to a main pulse of a MSK or GMSK waveform.

23. A method according to claim 18, which further comprises equalizing the communications signal within a block or symbol equalizer having a clamping circuit and clamping communications data symbols to a purely real symbol (+/−

1) or a purely imaginary symbol (+/−

j).

24. A method according to claim 18, which further comprises clamping even or odd communications data symbols to real symbols and clamping respective even or odd communications data symbols to imaginary symbols.

25. A method according to claim 18, which further comprises receiving and equalizing the communications signal and clamping communications data symbols based on a substantially fixed rotation mapping.