Direct determination equalizer system

• US 7,852,912 B2
• Filed: 03/25/2005
• Issued: 12/14/2010
• Est. Priority Date: 03/25/2005
• Status: Active Grant

• Current Assignee: Keysight Technologies, Inc.
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Viss, Marlin E., Woodward, Mark J.
• Primary Examiner(s): Ghayour; Mohammad H
• Assistant Examiner(s): Hassan; Sarah
• Application Number:
  US11/090,383
• Publication Number:
  US 20060215745A1
• Time in Patent Office: 2,090 Days
• Field of Search: 375/229, 375/232, 375/350, 375/239, 329/316
• US Class Current: 375/229
• CPC Class Codes: H04L 25/0305 using blind adaptation

Abstract

A direct determination equalizer system (“DDES”) for compensating for the deterministic effects of a transmission channel and a data source is disclosed. The DDES may include an equalizer having equalizer-tap coefficients, a cross-correlator configured to receive the first sampled signal and an ideal signal and in response produce a cross-correlated signal, and a processor in signal communication with the equalizer and the cross-correlator. The equalizer is configured to receive a first sampled signal and in response produce an equalized output data signal sequence and the processor is configured to determine the equalizer-tap coefficients from the cross-correlated signal.

Claims

1. A method for compensating for the deterministic effects of a transmission channel on an input data signal provided by a data source to an input of the transmission channel;

the method utilizing a direct determination equalizer system (“

DDES”

) having an equalizer, the method comprising;

acquiring a channel output data signal, comprising a sequence spanning multiple bits from an output of the transmission channel;

determining an ideal data signal;

cross-correlating the channel output data signal and the ideal data signal to produce a cross-correlation sequence comprising a plurality of terms, each term in said cross-correlation sequence corresponding to a different delay between said channel output data signal and said ideal data signal;

determining the delay corresponding to the largest value of the cross-correlation sequence;

determining equalizer-tap coefficients for the equalizer, the equalizer-tap coefficients depending on the determined delay; and

generating an equalized output data signal by applying the equalizer to an output of the transmission channel;

wherein determining the ideal data signal comprises sampling either the input data signal provided by the data source to the input of the transmission channel or the output data signal acquired from the output of the transmission channel to generate said ideal data signal.

2. The method of claim 1, wherein determining equalizer-tap coefficients for the equalizer includes:

producing a set of linear equations that depend linearly on the equalizer-tap coefficients based on the cross-correlation sequence, and

solving the set of linear equations for the equalizer-tap coefficients.

3. The method of claim 2, wherein cross-correlating the channel output data signal and the ideal data signal utilizes the relationship

4. The method of claim 3,

wherein the set of linear equations is produced utilizing the relationship

6. The method of claim 1, wherein determining an ideal data signal includes approximating an ideal data signal with an approximating sequence.

11. The method of claim 6,

wherein the approximating sequence has a sequence of logical bits;

wherein acquiring a channel output data signal sequence includes sampling the acquired channel output data signal sequence at a sampling rate, and

wherein approximating an ideal data signal includes;

sampling the sequence of logical bits at the sampling rate to produce the ideal data signal.

12. The method of claim 11, wherein cross-correlating the channel output data signal and the ideal data signal utilizes the relationship

13. The method of claim 12, wherein determining equalizer-tap coefficients for the equalizer includes:

producing a set of linear equations that depend linearly on the equalizer-tap coefficients based on the cross-correlation sequence, and

solving the set of linear equations for the equalizer-tap coefficients;

wherein the set of linear equations is produced utilizing the relationship

5. A method for compensating for the deterministic effects of a transmission channel on an input data signal provided by a data source to an input of the transmission channel;

the method utilizing a direct determination equalizer system (“

DDES”

) having an equalizer, the method comprising;

acquiring a channel output data signal sequence spanning multiple bits from an output of the transmission channel;

determining an ideal data signal;

cross-correlating the channel output data signal and the ideal data signal to produce a cross-correlated signal including a cross-correlation sequence;

determining the largest value of the cross-correlation sequence; and

determining equalizer-tap coefficients for the equalizer;

wherein determining an ideal data signal includes sampling either the data signal at the input of the transmission channel or the data signal at the output of the transmission channel to generate said ideal data signal.

7. A method for compensating for the deterministic effects of a transmission channel on an input data signal provided by a data source to an input of the transmission channel;

the method utilizing a direct determination equalizer system (“

DDES”

) having an equalizer, the method comprising;

acquiring a channel output data signal sequence spanning multiple bits from an output of the transmission channel;

determining an ideal data signal;

cross-correlating the channel output data signal and the ideal data signal to produce a cross-correlated signal including a cross-correlation sequence;

determining the largest value of the cross-correlation sequence; and

determining equalizer-tap coefficients for the equalizer;

wherein determining an ideal data signal includes sampling either the data signal at the input of the transmission channel or the data signal at the output of the transmission channel; and

wherein determining an ideal data signal includes approximating an ideal data signal with an approximating sequence; and

wherein acquiring a channel output data signal sequence includes sampling the acquired channel output data signal sequence at a sampling rate, and wherein approximating an ideal data signal includes;

determining a priori information for the ideal data signal;

generating the approximating sequence utilizing the a priori information; and

sampling a logical sequence of bits corresponding to the approximating sequence at the sampling rate to produce the ideal data signal.

8. The method of claim 7, wherein cross-correlating the channel output data signal and the ideal data signal utilizes the relationship

9. The method of claim 8, wherein determining equalizer-tap coefficients for the equalizer includes:

producing a set of linear equations based on the cross-correlation sequence; and

solving the set of linear equations;

wherein the set of linear equations is produced utilizing the relationship

10. The method of claim 9, wherein approximating an ideal data signal further includes filtering the produced ideal data signal.

14. A direct determination equalizer system (“

DDES”

) for compensating for the deterministic effects of a transmission channel receiving an input data signal sequence provided by a data source at an input of said channel and providing a corresponding output data signal at an output of said channel, the DDES comprising;

a first sampler that samples the output data signal to provide a first sampled signal;

an equalizer having equalizer-tap coefficients, wherein the equalizer is configured to receive the first sampled signal and in response produce an equalized output data signal sequence;

a second sampler that samples either the input data signal at the input of the transmission channel or the output data signal at the output of the transmission channel to provide an ideal signal;

a cross-correlator configured to receive the first sampled signal and the ideal signal and in response produce a cross-correlated signal; and

a processor in signal communication with the equalizer and the cross-correlator, wherein the processor is configured to determine the equalizer-tap coefficients from the cross-correlated signal.

15. A direct determination equalizer system (“

DDES”

) for compensating for the deterministic effects of a transmission channel receiving an input data signal sequence provided by a data source at an input of said channel and providing a corresponding output data signal at an output of said channel, the DDES comprising;

a first sampler that samples the output data signal to provide a first sampled signal;

an equalizer having equalizer-tap coefficients, wherein the equalizer is configured to receive the first sampled signal and in response produce an equalized output data signal sequence;

a second sampler that samples either the input data signal at the input of the transmission channel or the output data signal at the output of the transmission channel to provide an ideal signal;

a cross-correlator configured to receive the first sampled signal and the ideal signal and in response produce a cross-correlated signal;

a processor in signal communication with the equalizer and the cross-correlator, wherein the processor is configured to determine the equalizer-tap coefficients from the cross-correlated signal; and

a clock in signal communication with both the first sampler and the second sampler,

wherein the second sampler is configured to sample the input data signal sequence at the input of the transmission channel and produce the ideal signal;

wherein the clock is configured to produce a clock signal that is passed to the first sampler and the second sampler, and

wherein the clock signal produces the sampling rate for both the first sampler and the second sampler.

16. The DDES of claim 15, further including a detector in signal communication with both the cross-correlator and the processor, wherein the detector is configured to determine the largest value of the cross-correlation sequence.

17. A direct determination equalizer system (“

DDES”

) for compensating for the deterministic effects of a transmission channel receiving an input data signal sequence provided by a data source at an input of said channel and providing a corresponding output data signal at an output of said channel, the DDES comprising;

a first sampler that samples the output data signal to provide a first sampled signal;

an equalizer having equalizer-tap coefficients, wherein the equalizer is configured to receive the first sampled signal and in response produce an equalized output data signal sequence;

a second sampler that samples either the input data signal at the input of the transmission channel or the output data signal at the output of the transmission channel to provide an ideal signal;

a cross-correlator configured to receive the first sampled signal and the ideal signal and in response produce a cross-correlated signal;

a processor in signal communication with the equalizer and the cross-correlator, wherein the processor is configured to determine the equalizer-tap coefficients from the cross-correlated signal;

a sequence generator configured to produce an approximating sequence wherein the approximating sequence approximates the ideal data signal; and

a third sampler in signal communication with both the sequence generator and the cross-correlator, wherein the third sampler is configured to sample the approximating sequence to produce the ideal signal; and

a clock in signal communication with both the first sampler and the third sampler,

wherein the clock is configured to produce a clock signal that is passed to the first sampler and the third sampler, and

wherein the clock signal produces the sampling rate for both the first sampler and the third sampler.

18. The DDES of claim 17, wherein the sequence generator includes a threshold module.

19. The DDES of claim 18, further including a filter in signal communication with both the third sampler and the cross-correlator, wherein the filter is configured to filter the sampled approximating sequence to produce the ideal signal.

20. A computer-readable medium having software comprising instructions executable for compensating for the deterministic effects of a transmission channel on an input data signal provided by a data source to an input of the transmission channel, said compensating utilizing a direct determination equalizer system (“

DDES”

) having an equalizer, the medium comprising;

logic configured for acquiring a channel output data signal comprising a sequence spanning multiple bits from an output of the transmission channel;

logic configured for determining an ideal data signal;

logic configured for cross-correlating the channel output data signal and the ideal data signal to produce a cross-correlation sequence comprising a plurality of terms, each term in said cross-correlation sequence corresponding to a different delay between said channel output data signal and said ideal data signal;

logic configured for determining the delay corresponding to the largest value of the cross-correlation sequence;

logic configured for determining equalizer-tap coefficients for the equalizer, the equalizer-tap coefficients depending on the determined delay; and

logic configured for generating an equalized output data signal by applying the equalizer to an output of the transmission channel,

wherein determining the ideal data signal comprises sampling either the input data signal provided by the data source to the input of the transmission channel or the output data signal acquired from the output of the transmission channel to generate said ideal data signal.

21. The computer-readable medium of claim 20, wherein the logic configured for determining the equalizer-tap coefficients for the equalizer includes:

logic configured for producing a set of linear equations a set of linear equations that depend linearly on the equalizer-tap coefficients based on the cross-correlation sequence, and

logic configured for solving the set of equations for the equalizer-tap coefficients.

22. The computer-readable medium of claim 21, wherein the logic configured for cross-correlating the channel output data signal and the ideal data signal utilizes the relationship

23. The computer-readable medium of claim 22, wherein the logic configured for determining equalizer-tap coefficients for the equalizer includes:

logic configured for producing a set of linear equations based on the cross-correlation sequence; and

logic configured for solving the set of linear equations;

wherein the set of linear equations are produced utilizing the relationship

26. The computer-readable medium of claim 20, wherein the logic configured for determining the ideal data signal includes logic configured for approximating the ideal data signal with an approximating sequence.

30. The computer-readable medium of claim 26, wherein the logic configured for acquiring a channel output data signal sequence includes logic configured for sampling the acquired channel output data signal sequence at a sampling rate, and wherein the logic configured for approximating the ideal data signal includes;

logic configured for generating the approximating sequence corresponding to the acquired channel output data signal, the approximating sequence having a sequence of logical bits; and

logic configured for sampling the sequence of logical bits at the sampling rate to produce the ideal data signal.

31. The computer-readable medium of claim 30, wherein the logic configured for cross-correlating the channel output data signal and the ideal data signal utilizes the relationship

32. The computer-readable medium of claim 31, wherein the logic configured for determining equalizer-tap coefficients for the equalizer includes:

logic configured for producing a set of linear equations that depend linearly on the equalizer-tap coefficients based on the cross-correlation sequence, and

logic configured for solving the set of linear equations for the equalizer-tap coefficients;

wherein the set of linear equations are produced utilizing the relationship

24. A computer-readable medium having software comprising instructions executable for compensating for the deterministic effects of a transmission channel on an input data signal provided by a data source to an input of the transmission channel, said compensating utilizing a direct determination equalizer system (“

DDES”

) having an equalizer, the medium comprising;

logic configured for acquiring a channel output data signal sequence spanning multiple bits from an output of the transmission channel;

logic configured for determining an ideal data signal;

logic configured for cross-correlating the channel output data signal and the ideal data signal to produce a cross-correlation signal having a cross-correlation sequence;

logic configured for determining the largest value of the cross-correlation sequence; and

logic configured for determining equalizer-tap coefficients for the equalizer;

wherein determining an ideal data signal includes sampling either the data signal at the input of the transmission channel or the data signal at the output of the transmission channel to generate said ideal data signal; and

wherein the logic configured for determining the equalizer-tap coefficients for the equalizer includes;

logic configured for producing a set of linear equations based on the cross-correlation sequence; and

logic configured for solving the set of linear equations; and

wherein the logic configured for solving includes logic configured for solving the set of linear equations utilizing linear regression.

25. A computer-readable medium having software comprising instructions executable for compensating for the deterministic effects of a transmission channel on an input data signal provided by a data source to an input of the transmission channel, said compensating utilizing a direct determination equalizer system (“

DDES”

) having an equalizer, the medium comprising;

logic configured for acquiring a channel output data signal sequence spanning multiple bits from an output of the transmission channel;

logic configured for determining an ideal data signal;

logic configured for cross-correlating the channel output data signal and the ideal data signal to produce a cross-correlation signal having a cross-correlation sequence;

logic configured for determining the largest value of the cross-correlation sequence; and

logic configured for determining equalizer-tap coefficients for the equalizer;

wherein determining an ideal data signal includes sampling either the data signal at the input of the transmission channel or the data signal at the output of the transmission channel; and

wherein the logic configured for determining an ideal data signal includes logic configured for determining an ideal data signal by sampling the input data signal at the input of the transmission channel to generate said ideal data signal.

27. A computer-readable medium having software comprising instructions executable for compensating for the deterministic effects of a transmission channel on an input data signal provided by a data source to an input of the transmission channel, said compensating utilizing a direct determination equalizer system (“

DDES”

) having an equalizer, the medium comprising;

logic configured for acquiring a channel output data signal sequence spanning multiple bits from an output of the transmission channel;

logic configured for determining an ideal data signal;

logic configured for cross-correlating the channel output data signal and the ideal data signal to produce a cross-correlation signal having a cross-correlation sequence;

logic configured for determining the largest value of the cross-correlation sequence; and

logic configured for determining equalizer-tap coefficients for the equalizer;

wherein determining an ideal data signal includes sampling either the data signal at the input of the transmission channel or the data signal at the output of the transmission channel; and

wherein the logic configured for determining the ideal data signal includes logic configured for approximating the ideal data signal with an approximating sequence; and

wherein the logic configured for acquiring a channel output data signal sequence includes logic configured for sampling the acquired channel output data signal sequence at a sampling rate, and wherein the logic configured for approximating the ideal data signal includes;

logic configured for determining a priori information for the ideal data signal;

logic configured for generating the approximating sequence utilizing the a priori information; and

logic configured for sampling a logical sequence of bits corresponding to the approximating sequence at the sampling rate to produce the ideal data signal.

28. The computer-readable medium of claim 27, wherein the logic configured for cross-correlating the channel output data signal and the ideal data signal utilizes the relationship

29. The computer-readable medium of claim 28, wherein the logic configured for determining equalizer-tap coefficients for the equalizer includes:

logic configured for producing a set of linear equations based on the cross-correlation sequence; and

logic configured for solving the set of linear equations;

wherein the set of linear equations are produced utilizing the relationship