Equalizers for layered modulated and other signals

• US 8,208,526 B2
• Filed: 03/13/2009
• Issued: 06/26/2012
• Est. Priority Date: 04/27/2001
• Status: Expired due to Term

• Current Assignee: DIRECTV, LLC (AT&T, Inc.)
• Original Assignee: The DIRECTV Group, Inc. (AT&T, Inc.)
• Inventors: Chen, Ernest C., Lin, Tung-Sheng, Wang, Weizheng, Lindsey, William C.
• Primary Examiner(s): Bayard, Emmanuel
• Application Number:
  US12/404,253
• Publication Number:
  US 20090175327A1
• Time in Patent Office: 1,201 Days
• Field of Search: 375229-235, 375/346, 375/348
• US Class Current: 375/231
• CPC Class Codes: H04L 2025/03401 PSK
• CPC Class Codes: H04L 2025/0342 QAM
• CPC Class Codes: H04L 2025/0349 as a feedback filter
• CPC Class Codes: H04L 25/03019 adaptive, i.e. capable of adjustment during data reception
• CPC Class Codes: H04L 27/3488 Multiresolution systems

Abstract

A method and apparatus for equalizing digital data signals is disclosed. The method comprises the steps of demodulating and decoding an input signal having input data to produce a data output, remodulating the data output to produce a training sequence including an idealized input signal, wherein the training sequence is comprised of adjacent symbols in the input data, and generating equalizer parameters from the training sequence. The apparatus comprises a demodulator (for demodulating an input signal to produce a data output), a modulator communicatively coupled to the demodulator (for remodulating the data output to produce a training sequence including an idealized input signal wherein the training sequence is comprised of adjacent symbols in the input data), and a parameter generation module communicatively coupled to the modulator (for generating equalizer parameters from the training sequence).

Claims

1. A method of equalizing digital data signals, comprising:

demodulating an input signal having input data;

decoding the demodulated input signal to produce a data output;

re-encoding the data output;

remodulating the re-encoded data output to produce a training sequence, wherein the training sequence is comprised of adjacent symbols in the input data; and

generating equalizer parameters from the training sequence.

2. The method of claim 1, wherein the step of generating equalizer parameters comprises comparing the training sequence with the input signal to determine channel distortion.

3. The method of claim 2, wherein the step of generating equalizer parameters comprises subtracting the adjacent symbols from the input signal to reproduce channel impairments, wherein the channel impairments are subtracted from the input signal for equalization.

4. The method of claim 3, wherein the channel impairments comprise inter-symbol interference.

5. The method of claim 1, wherein the step of generating equalizer parameters from the remodulated data output comprises:

buffering the input signal; and

comparing the buffered input signal to the training sequence to produce the equalizer parameters.

6. An apparatus for equalizing digital data signals, comprising:

means for demodulating an input signal having input data;

means for decoding the input signal to produce a data output;

means for re-encoding the data output;

means for remodulating the re-encoded data output to produce a training sequence, wherein the training sequence is comprised of adjacent symbols in the input data; and

means for generating equalizer parameters from the training sequence.

7. The apparatus of claim 6, wherein the means for generating equalizer parameters comprises means for comparing the training sequence with the input signal to determine channel distortion.

8. The apparatus of claim 7, wherein the means for generating equalizer parameters comprises means for subtracting the adjacent symbols from the input signal to reproduce channel impairments, wherein the channel impairments are subtracted from the input signal for equalization.

9. The apparatus of claim 8, wherein the channel impairments comprise inter-symbol interference.

10. The apparatus of claim 6, wherein the means for generating equalizer parameters from the remodulated data output comprises:

means for buffering the input signal; and

means for comparing the buffered input signal to the training sequence to produce the equalizer parameters.

11. An apparatus for equalizing digital data signals comprising:

a demodulator for demodulating an input signal;

a decoder for decoding the input signal to produce a data output;

a re-encoder for re-encoding the data output;

a modulator, communicatively coupled to the demodulator, for remodulating the re-encoded data output to produce a training sequence, wherein the training sequence is comprised of adjacent symbols in the input data; and

a parameter generation module, communicatively coupled to the modulator, for generating equalizer parameters from the training sequence.

12. The apparatus of claim 11, wherein the parameter generation module compares the training sequence with the input signal to determine channel distortion.

13. The apparatus of claim 12, wherein the parameter generation module subtracts the adjacent symbols from the input signal to reproduce channel impairments, wherein the channel impairments are subtracted from the input signal for equalization.

14. The apparatus of claim 13, wherein the channel impairments comprise inter-symbol interference.

15. The apparatus of claim 11, wherein the parameter generation module comprises:

means for buffering the input signal; and

means for comparing the buffered input signal to the training sequence to produce the equalizer parameters.

16. A method of equalizing digital data signals, comprising:

demodulating an input signal having input data to produce a data output;

remodulating the data output to produce a training sequence, wherein the training sequence is comprised of adjacent symbols in the input data; and

generating equalizer parameters from the training sequence, comprising the step of comparing the training sequence with the input signal to determine channel distortion.

17. The method of claim 16, wherein the step of generating equalizer parameters comprises subtracting the adjacent symbols from the input signal to reproduce channel impairments, wherein the channel impairments are subtracted from the input signal for equalization.

18. The method of claim 17, wherein the channel impairments comprise inter-symbol interference.

19. The method of claim 16, wherein the step of generating equalizer parameters from the remodulated data output comprises:

buffering the input signal; and

comparing the buffered input signal to the training sequence to produce the equalizer parameters.

20. A method of equalizing digital data signals, comprising:

demodulating an input signal having input data to produce a data output;

remodulating the data output to produce a training sequence, wherein the training sequence is comprised of adjacent symbols in the input data; and

generating equalizer parameters from the training sequence, comprising the steps of;

buffering the input signal; and

comparing the buffered input signal to the training sequence to produce the equalizer parameters.

21. An apparatus for equalizing digital data signals, comprising:

means for demodulating an input signal having input data to produce a data output;

means for remodulating the data output to produce a training sequence, wherein the training sequence is comprised of adjacent symbols in the input data; and

means for generating equalizer parameters from the training sequence, comprising means for comparing the training sequence with the input signal to determine channel distortion.

22. The apparatus of claim 21, wherein the means for generating equalizer parameters comprises means for subtracting the adjacent symbols from the input signal to reproduce channel impairments, wherein the channel impairments are subtracted from the input signal for equalization.

23. The apparatus of claim 22, wherein the channel impairments comprise inter-symbol interference.

24. The apparatus of claim 21, wherein the means for generating equalizer parameters from the remodulated data output comprises:

means for buffering the input signal; and

means for comparing the buffered input signal to the training sequence to produce the equalizer parameters.

25. An apparatus for equalizing digital data signals, comprising:

means for demodulating an input signal having input data to produce a data output;

means for remodulating the data output to produce a training sequence, wherein the training sequence is comprised of adjacent symbols in the input data; and

means for generating equalizer parameters from the training sequence, comprising;

means for buffering the input signal; and

means for comparing the buffered input signal to the training sequence to produce the equalizer parameters.

26. An apparatus for equalizing digital data signals comprising:

a demodulator for demodulating an input signal to produce a data output;

a modulator, communicatively coupled to the demodulator, for remodulating the data output to produce a training sequence, wherein the training sequence is comprised of adjacent symbols in the input data; and

a parameter generation module, communicatively coupled to the modulator, for generating equalizer parameters from the training sequence, wherein the parameter generation module compares the training sequence with the input signal to determine channel distortion.

27. The apparatus of claim 26, wherein the parameter generation module subtracts the adjacent symbols from the input signal to reproduce channel impairments, wherein the channel impairments are subtracted from the input signal for equalization.

28. The apparatus of claim 27, wherein the channel impairments comprise inter-symbol interference.

29. The apparatus of claim 26, wherein the parameter generation module comprises:

means for buffering the input signal; and

means for comparing the buffered input signal to the training sequence to produce the equalizer parameters.

30. An apparatus for equalizing digital data signals comprising:

a demodulator for demodulating an input signal to produce a data output;

a modulator, communicatively coupled to the demodulator, for remodulating the data output to produce a training sequence, wherein the training sequence is comprised of adjacent symbols in the input data; and

a parameter generation module, communicatively coupled to the modulator, for generating equalizer parameters from the training sequence, comprising;

means for buffering the input signal; and

means for comparing the buffered input signal to the training sequence to produce the equalizer parameters.