System and method of validating equalizer training

• US 6,445,734 B1
• Filed: 06/30/1999
• Issued: 09/03/2002
• Est. Priority Date: 06/30/1999
• Status: Expired due to Term

• Current Assignee: Synaptics Incorporated
• Original Assignee: Conexant Systems Incorporated (Synaptics Incorporated)
• Inventors: Chen, Li, Aminian, Farhad, Chu, Keith T.
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Ha, Dac V.
• Application Number:
  US09/343,873
• Time in Patent Office: 1,161 Days
• Field of Search: 375/229-232, 375/346, 375/348, 375/350, 375/222, 708/322, 708/323, 708/305
• US Class Current: 375/231
• CPC Class Codes: H04L 2025/03707 Detection or avoidance of local extrema
• CPC Class Codes: H04L 25/03038 with a non-recursive structure H04L25/03031 takes precedence

Abstract

Equalizer training is validated by techniques to detect false training. The validation techniques involve checking the unique time domain energy shaping of a plurality of taps of a trained equalizer of a modem for good training. The energy measure for each equalizer tap of the plurality of taps is approximated by summing the magnitude of a real component and a magnitude of an imaginary component of an equalizer coefficient corresponding to the equalizer tap. A tap with a highest approximate energy (i.e., the main tap) is then determined. Next, the main tap energy is compared to a main tap threshold and a predetermined guarding threshold. The plurality of taps are arranged in a time index ordered sequence. In determining the main tap threshold, a first energy sum of a beginning set of taps in the sequence is compared with a second energy sum of a last set of taps in the sequence. The lesser tap energy sum between the first energy sum and the second energy sum is the main tap threshold. The main tap is then compared with the main tap threshold and the predetermined guarding threshold. If the main tap is greater than the main tap threshold and the predetermined guarding threshold, then the train of the equalizer is good. If the main tap is less than the main tap threshold or the predetermined guarding threshold, then the train of the equalizer is false. The above-mentioned validation techniques are effective to recognize the unique time domain energy shaping characteristics of good-trained equalizer taps.

Claims

1. A modem configured to validate equalizer training, comprising:

a host controller; and

a data pump coupled to the host controller, the data pump comprising;

an equalizer; and

a memory device coupled to the equalizer, the memory device comprising;

equalizer training validation code executable by the data pump, the code comprising;

energy measurement code to approximately measure the energy for each tap of a plurality of taps for the equalizer;

main tap detection code to detect a main tap with a highest approximate energy, the plurality of taps including the main tap;

main tap threshold calculation code to calculate a main tap threshold;

main tap threshold analysis code to compare the main tap threshold with a predetermined guarding threshold; and

main tap compare code to compare the main tap threshold and the main tap if the main tap threshold is greater than the predetermined guarding threshold and to compare the predetermined guarding threshold and the main tap if the main tap threshold is less than the predetermined guarding threshold.

2. The modem of claim 1, the main tap threshold calculation code, comprising:

first energy summation code to calculate a first energy sum for a beginning set of taps from the plurality of taps;

second energy summation code to calculate a second energy sum for a last set of taps from the plurality of taps;

energy sum compare code to compare the first energy sum and the second energy sum; and

main tap threshold identification code to treat the first energy sum as the main tap threshold if the first energy sum is less than the second energy sum and to treat the second energy sum as the main tap threshold if the second energy sum is less than the first energy sum.

3. The modem of claim 1, the energy measurement code, comprising:

code to approximate the energy of each tap of the plurality of taps by summing a magnitude of a real component and a magnitude of an imaginary component of each equalizer coefficient corresponding to each tap.

4. The modem of claim 1, wherein the equalizer comprises a V.34 half-duplex equalizer.

5. The modem of claim 1, wherein if the main tap is compared to the main tap threshold and the predetermined guarding threshold and the main tap is greater than the main tap threshold and the predetermined guarding threshold, then the equalizer corresponds to a good train, and if the main tap is less than the main tap threshold or the predetermined guarding threshold, then the equalizer corresponds to a false train.

6. An integrated circuit, comprising:

a memory device executable by a data pump, comprising;

equalizer training validation code, comprising;

energy measurement code to approximately measure the energy for each tap of a plurality of taps for the equalizer;

main tap detection code to detect a main tap with a highest approximate energy, the plurality of taps including the main tap;

main tap threshold calculation code to calculate a main tap threshold; and

main tap threshold analysis code to compare the main tap threshold with a predetermined guarding threshold; and

main tap compare code to compare the main tap threshold and the main tap if the main tap threshold is greater than the predetermined guarding threshold and to compare the predetermined guarding threshold and the main tap if the main tap threshold is less than the predetermined guarding threshold.

7. The integrated circuit of claim 6, the main tap threshold calculation code, comprising:

first energy summation code to calculate a first energy sum for a beginning set of taps from the plurality of taps;

second energy summation code to calculate a second energy sum for a last set of taps from the plurality of taps;

energy sum compare code to compare the first energy sum and the second energy sum; and

main tap threshold identification code to treat the first energy sum as the main tap threshold if the first energy sum is less than the second energy sum and to treat the second energy sum as the main tap threshold if the second energy sum is less than the first energy sum.

8. The integrated circuit of claim 6, the energy measurement code, comprising:

code to approximate the energy of each tap of the plurality of taps by summing a magnitude of a real component and a magnitude of an imaginary component of each equalizer coefficient corresponding to each tap.

9. The integrated circuit of claim 6, wherein if the main tap is compared to the main tap threshold and the predetermined guarding threshold and the main tap is greater than the main tap threshold and the predetermined guarding threshold, then the equalizer corresponds to a good train, and if the main tap is less than the main tap threshold or the predetermined guarding threshold, then the equalizer corresponds to a false train.

10. The integrated circuit of claim 6, further comprising:

an equalizer coupled to the memory device.

11. A method of validating equalizer training, comprising the steps of:

approximately measuring the energy for each tap of a plurality of taps for an equalizer;

detecting a main tap with a highest approximate energy, the plurality of taps including the main tap;

calculating a main tap threshold;

comparing the main tap threshold with a predetermined guarding threshold;

comparing the main tap and the main tap threshold if the main tap threshold is greater than the predetermine guarding threshold; and

comparing the main tap and the predetermined guarding threshold if the main tap threshold is less than the predetermine guarding threshold.

12. The method of claim 11, the calculating step comprising the steps of:

calculating a first energy sum for a beginning set of taps from the plurality of taps;

calculating a second energy sum for a last set of taps from the plurality of taps;

comparing the first energy sum and the second energy sum;

treating the first energy sum as the main tap threshold if the first energy sum is less than the second energy sum; and

treating the second energy sum as the main tap threshold if the second energy sum is less than the first energy sum.

13. The method of claim 11, the measuring step comprising the step of:

approximating the energy of each tap of the plurality of taps by summing a magnitude of a real component and a magnitude of an imaginary component of each equalizer coefficient corresponding to each tap.

14. The method of claim 11, wherein if the main tap is compared to the main tap threshold and the predetermined guarding threshold and the main tap is greater than the main tap threshold and the predetermined guarding threshold, then the equalizer corresponds to a good train, and if the main tap is less than the main tap threshold or the predetermined guarding threshold, then the equalizer corresponds to a false train.

15. A processor readable medium, comprising:

equalizer training validation code, comprising;

energy measurement code to approximately measure the energy for each tap of a select plurality of taps for the equalizer;

main tap detection code to detect a main tap with a highest approximate energy, the select plurality of taps including the main tap;

main tap threshold calculation code to calculate a main tap threshold;

main tap threshold analysis code to compare the main tap threshold with a predetermined guarding threshold; and

main tap compare code to compare the main tap threshold and the main tap if the main tap threshold is greater than the predetermined guarding threshold and to compare the predetermined guarding threshold and the main tap if the main tap threshold is less than the predetermined guarding threshold.

16. The processor readable medium of claim 15, the main tap threshold calculation code, comprising:

first energy summation code to calculate a first energy sum for a beginning set of taps from the select plurality of taps;

second energy summation code to calculate a second energy sum for a last set of taps from the plurality of taps;

energy sum compare code to compare the first energy sum and the second energy sum; and

main tap threshold identification code to treat the first energy sum as the main tap threshold if the first energy sum is less than the second energy sum and to treat the second energy sum as the main tap threshold if the second energy sum is less than the first energy sum.

17. The processor readable medium of claim 15, the energy measurement code, comprising:

code to approximate the energy of each tap of the plurality of taps by summing a magnitude of a real component and a magnitude of an imaginary component of each equalizer coefficient corresponding to each tap.

18. The processor readable medium of claim 15, wherein if the main tap is compared to the main tap threshold and the predetermined guarding threshold and the main tap is greater than the main tap threshold and the predetermined guarding threshold, then the equalizer corresponds to a good train, and if the main tap is less than the main tap threshold or the predetermined guarding threshold, then the equalizer corresponds to a false train.

19. An integrated circuit, comprising:

a data pump configured to perform the following steps;

approximately measuring the energy for each tap of a plurality of taps for an equalizer;

detecting a main tap with a highest approximate energy, the plurality of taps including the main tap;

calculating a main tap threshold;

comparing the main tap threshold with a predetermined guarding threshold;

comparing the main tap and the main tap threshold if the main tap threshold is greater than the predetermine guarding threshold; and

comparing the main tap and the predetermined guarding threshold if the main tap threshold is less than the predetermine guarding threshold.

20. The integrated circuit of claim 19, the calculating step comprising the steps of:

calculating a first energy sum for a beginning set of taps from the plurality of taps;

calculating a second energy sum for a last set of taps from the plurality of taps;

comparing the first energy sum and the second energy sum;

treating the first energy sum as the main tap threshold if the first energy sum is less than the second energy sum; and

treating the second energy sum as the main tap threshold if the second energy sum is less than the first energy sum.

21. The integrated circuit of claim 19, the measuring step comprising the step of:

approximating the energy of each tap of the plurality of taps by summing a magnitude of a real component and a magnitude of an imaginary component of each equalizer coefficient corresponding to each tap.