Method and device for estimating transmitted signals in a receiver in digital signal transmission operations

In a method of receiving successive digital symbols transmitted over a communication channel that uses a viterbi algorithm, a method of estimating transmitted symbols comprising the steps of:

• (a) sampling a received signal at a recurrent plurality of time points during each received symbol;
• (b) designating one of the plurality of time points as a symbol sampling time point;
• (c) selecting at least two samples for each received symbol, the selected samples being generated at the symbol sampling point and at least one other time point;
• (d) correlating the samples generated by step (a) with a predetermined sequence to produce at least an initial estimated impulse response of the communication channel;
• (e) generating coefficients of a prefilter based on the estimated impulse response and weight factor corresponding to the symbol sampling time point and the at least one other time point, and prefiltering the selected samples;
• (f) generating coefficients of a metric calculation filter based on the estimated impulse response and the coefficients of the prefilter;
• and
• (g) generating at least preliminary estimated symbols according to the viterbi algorithm using the prefiltered samples and the coefficients of the metric calculation filter.

In a receiver of successive digital symbols transmitted over a communication channel that uses a viterbi algorithm, an apparatus for estimating transmitted symbols comprising:

• means for sampling a received signal at a sampling time point during during each received symbol;
• means for correlating the samples generated by the sampling means with a predetermined sequence to produce at least an initial estimated impulse response of the communication channel;
• means for generating prefilter coefficients based on an adapted estimated impulse response and prefiltering the samples;
• a metric calculation filter having coefficients based on the prefilter coefficients and the adapted estimated impulse response;
• and
• channel equalizer means for generating at least preliminary estimated symbols using the viterbi algorithm based on the prefiltered samples and the coefficients of the metric calculation filter;
• means for generating estimated signal values based on the estimated impulse response and the preliminary estimated symbols;
• means for generating error signal according to differences between the samples of the received signal and the estimated signal values;
• and
• means for generating the adapted estimated impulse response using the preliminary estimated symbols and the error signal, according to a chosen adaptation algorithm.

In a receiver of successive digital symbols transmitted over a communication channel that uses a viterbi algorithm, an apparatus for estimating transmitted symbols comprising:

• means for sampling a received signal at a recurrent plurality of time points during each received symbol;
• means for designating one of the plurality of time points as a symbol sampling time point;
• means, connected to the sampling means, for selecting at least two samples for each received symbol, the selected samples being the samples generated at the symbol sampling time point and at least one other time point;
• means for correlating the samples generated by the sampling means with a predetermined sequence to produce at least an initial estimated impulse response of the communication channel;
• means for generating coefficients of a prefilter based on the estimated impulse response and weight factors corresponding to the symbol sampling time point and the at least one other time point, and prefiltering the samples;
• a metric calculation filter having coefficients based on the prefilter coefficients;
• channel equalizer means for generating at least preliminary estimated symbols according to the viterbi algorithm based on the prefiltered samples and the coefficients of the metric calculation filter;
• and
• means for generating the weight factor for the corresponding selected samples.