Device and method for estimating sampled value of impulse response and signal reproduction system using the device

A device for estimating a sampled value of an impulse response from an input signal and an output signal of a decision circuit which performs a signal decision procedure for reproducing a digital signal, the input signal having an equalized waveform, said device comprising:

• first means, operatively coupled to the decision circuit, for generating a first sum of absolute values of j (where j is a natural number) samples of decided values obtained from the output signal of the decision circuit;
• second means, operatively coupled to the decision circuit, for generating a second sum of absolute values of j samples of equalized outputs obtained from the input signal of the decision circuit;
• and
• third means, operatively coupled to said first and second means, for generating a dividing ratio using said first sum and said second sum, and said ratio being an estimate of the sampled value of the impulse response at a sampling point shifted by a predetermined amount.

A method for estimating a sampled value of an impulse response from an input signal and an output signal of a decision circuit which performs a signal decision procedure for reproducing a digital signal, said input signal having an equalized waveform, said method comprising the steps of:

• generating first absolute values of samples of decided values obtained from the output signal of the decision circuit;
• generating second absolute values of samples of equalized outputs obtained from the input signal of the decision circuit;
• and
• generating a dividing ratio using said first absolute values and said second absolute values, and said dividing ratio being an estimate of the sampled value of the impulse response at a sampling point shifted by a predetermined amount.

A method for estimating a sampled value of an impulse response from an input signal and an output signal of a decision circuit which performs a signal decision procedure for reproducing a digital signal, said input signal having an equalized waveform, said method comprising the steps of:

• generating a first sum of absolute values of j (where j is a natural number) samples of decided values obtained from the output signal of the decision circuit;
• generating a second sum of absolute values of j samples of equalized outputs obtained from the input signal of the decision circuit;
• and
• generating a ratio of said first sum and said second sum, and said ratio being an estimate of the sampled value of the impulse response at a sampling point.

A signal reproduction system coupled to a transmission line, said system comprising:

• waveform equalizing means for equalizing a digital input signal transmitted via the transmission line and for generating an equalized input signal;
• decision means, operatively coupled to said waveform equalizing means, for performing a decision procedure for the equalized input signal at a timing and for generating a reproduced digital signal;
• and
• timing reproduction means, operatively coupled to said waveform equalizing means and said decision means, for generating a clock signal from said equalized input signal and said reproduced digital signal, said clock signal defining said timing of said decision means, and said timing reproduction means comprising:
• first means, operatively coupled to said decision means, for generating first absolute values of samples of decided values obtained from the reproduced digital signal output by the decision means;
• second means, operatively coupled to said decision means, for generating second absolute values of samples of equalized outputs obtained from the equalized input signal input to said decision means;
• third means, operatively coupled to said first and second means, for generating a dividing ratio using said first absolute values and said second absolute values, said ratio being an estimate of a sampled value of an impulse response at a sampling point shifted by a predetermined amount;
• and
• control means, operatively coupled to said third means, for comparing said sampled value output by said third means with a threshold value and for adjusting said timing of said clock signal on the basis of a result of comparison.

A signal reproduction system coupled to a transmission line, said system comprising:

• waveform equalizing means for equalizing a digital input signal transmitted via the transmission line using an adjustable gain and for generating an equalized input signal;
• decision means, operatively coupled to said waveform equalizing means, for performing a decision procedure for the equalized input signal at a timing and for generating a reproduced digital signal;
• and
• gain control means, operatively coupled to said waveform equalizing means and said decision means, for controlling the gain of said waveform equalizing means, said gain control means comprising:
• first means, operatively coupled to said decision means, for generating first absolute values of samples of decided values obtained from the reproduced digital signal output by the decision means;
• second means, operatively coupled to said decision means, for generating second absolute values of samples of equalized outputs obtained from the equalized input signal input to the decision means;
• third means, operatively coupled to said first and second means, for generating a dividing ratio using said first absolute values and said second absolute values, and said ratio being an estimate of a sampled value of an impulse response at a sampling point shifted by a predetermined amount;
• and
• adjusting control means, operatively coupled to said third means, for comparing said sampled value output by said third means with a threshold value and for adjusting the gain of said waveform equalizing means for equalizing the waveform of said digital input signal on the basis of a result of comparison.

A signal reproduction system coupled to a transmission line, said system comprising:

• waveform equalizing means for equalizing a digital input signal transmitted via the transmission line and for generating an equalized input signal;
• decision means, operatively coupled to said waveform equalizing means, for performing a decision procedure for the equalized input signal at a timing and for generating a reproduced digital signal;
• and
• timing reproduction means, operatively coupled to said waveform equalizing means and said decision means, for generating a clock signal from said equalized input signal and said reproduced digital signal, said clock signal defining said timing of said decision means, said timing reproduction means comprising:
• first means, operatively coupled to said decision means, for generating a first sum of absolute values of j (where j is a natural number) samples of decided values obtained from the reproduced digital signal of the decision means;
• second means, operatively coupled to said decision means, for generating a second sum of absolute values of j samples of equalized outputs obtained from the equalized input signal of said decision means;
• third means, operatively coupled to said first and second means, for generating a ratio of said first sum of said second sum, and said ratio being an estimate of a sampled value of an impulse response at a sampling point;
• and
• control means, operatively coupled to said third means, for comparing said sampled value output by said third means with a threshold value and for adjusting the timing of said clock signal on the basis of a result of comparison.

A signal reproduction system coupled to a transmission line, said system comprising:

• waveform equalizing means for equalizing a digital input signal transmitted via the transmission line using an adjustable gain and for generating an equalized input signal;
• decision means, operatively coupled to said waveform equalizing means, for performing a decision procedure for the equalized input signal at a timing and for generating a reproduced digital signal;
• and
• gain control means, operatively coupled to said waveform equalizing means and said decision means, for controlling the gain of said waveform equalizing means, said gain control means comprising:
• first means, operatively coupled to said decision means, for generating a first sum of absolute values of j (where j is a natural number) samples of decided values obtained from the reproduced digital signal of said decision means;
• second means, operatively coupled to said decision means, for generating a second sum of absolute values of j samples of equalized outputs obtained from the equalized input signal of said decision means;
• third means, operatively coupled to said first and second means, for generating a ratio of said first sum and said second sum, said ratio being an estimate of a sampled value of an impulse response at a sampling point;
• and
• adjusting control means, operatively coupled to said third means, for comparing said sampled value output by said third means with a threshold value and for adjusting the gain of said waveform equalizing means for equalizing the waveform of said digital input signal on the basis of a result of comparison.