Methods and apparatus for implementing multi-tone receivers

An apparatus for processing a signal used to communicate a block of data representing at least one symbol, the apparatus comprising:

• a Fourier transform circuit for performing at least one Fourier transform on said signal;
• a buffer coupled to said Fourier transform circuit for buffering data produced from an output of said Fourier transform circuit;
• a jitter compensation filter coupled to said buffer for performing a filtering operation on data obtained from said buffer corresponding to said block of data to generate a filtered block of data, the jitter compensation filter having an update input for receiving a filter coefficient update signal;
• and
• an error calculation module coupled to the update input of the jitter compensation filter, the error calculation module generating the filter coefficient update signal from at least one signal error estimate made from the filtered block of data output by the jitter compensation filter, wherein the error calculation module includes:
• means for generating a decision directed error value;
• means for generating a pilot directed error value;
• and
• a selection device for selecting one of the decision directed error value and the pilot directed error value to be output.

An apparatus for processing a signal used to communicate a block of data representing at least one symbol, the apparatus comprising:

• a Fourier transform circuit for performing at least one Fourier transform on a said signal;
• a buffer coupled to said Fourier transform circuit for buffering data produced from an output of said Fourier transform circuit;
• a jitter compensation filter coupled to said buffer for performing a filtering operation on data obtained from said buffer corresponding to said block of data to generate a filtered block of data, the jitter compensation filter having an update input for receiving a filter coefficient update signal;
• and
• an error calculation module coupled to the update input of the jitter compensation filter, the error calculation module generating the filter coefficient update signal from at least one signal error estimate made from the filtered block of data output by the jitter compensation filter, wherein the error calculation module includes:
• means for generating a decision directed error value;
• means for generating a non-decision directed error value;
• and
• a selection device for selecting one of the decision directed error value and the non-decision directed error value to be output.

An apparatus for processing a signal used to communicate a block of data representing at least one symbol, the apparatus comprising:

• a Fourier transform circuit for performing at least one Fourier transform on said signal;
• a buffer coupled to said Fourier transform circuit for buffering data produced from an output of said Fourier transform circuit;
• a jitter compensation filter coupled to said buffer for performing a filtering operation on data obtained from said buffer corresponding to said block of data to generate a filtered block of data, the jitter compensation filter having an update input for receiving a filter coefficient update signal, said buffer storing said block of data while said block of data is processed multiple times by said jitter compensation filter;
• an error calculation module coupled to the update input of the jitter compensation filter, the error calculation module generating the filter coefficient update signal from at least one signal error estimate made from the filtered block of data output by the jitter compensation filter;
• and
• an output control device for determining when to output the filtered block of data generated by said jitter compensation filter.

A system for processing a multi-tone signal, the system including:

• a Fourier transform circuit for performing at least one Fourier transform on said multi-tone signal;
• a channel compensation module coupled to said Fourier transform circuit for performing a channel compensation operation on said multi-tone signal after processing by said Fourier transform circuit;
• a buffer coupled to said Fourier transform circuit for buffering the channel compensated multi-tone signal;
• a jitter compensation module coupled to said buffer for performing a jitter reduction operation on the buffered channel compensated multi-tone signal, wherein the jitter compensation module includes:
• a jitter compensation filter with programmable filter tap weights, and means for iteratively updating the filter tap weights as a function of the jitter compensation filter output;
• and
• a control circuit for determining when the output of the jitter compensation filter should be used as the output of the jitter compensation module.

A system for processing a multi-tone signal, the system including:

• a Fourier transform circuit for performing at least one Fourier transform on said multi-tone signal;
• a channel compensation module coupled to said Fourier transform circuit for performing a channel compensation operation on said multi-tone signal after processing by said Fourier transform circuit;
• a buffer coupled to said Fourier transform circuit for buffering the channel compensated multi-tone signal;
• a jitter compensation module coupled to said buffer for performing a jitter reduction operation on the buffered channel compensated multi-tone signal, wherein the jitter compensation module includes:
• a jitter compensation filter with programmable filter tap weights, and means for iteratively updating the filter tap weights as a function of the jitter compensation filter output, wherein the means for iteratively updating the filter tap weights includes a signal error estimation circuit for generating from the output of the jitter compensation filter a measure of a symbol error;
• and
• means for resetting the jitter compensation filter tap weights to an initial set of values in response to the control circuit determining that the output of the jitter compensation filter should be used as the output of the jitter compensation filter.

A method of processing a multi-tone signal, the method comprising the steps of:

• performing a Fourier transform operation on the multi-tone signal;
• buffering a block of samples produced from the output of said Fourier transform operation;
• and
• performing a jitter compensation operation, said jitter compensation operation including:
• i) operating a filter having a plurality of tap weights to filter said block of samples to produce a filtered block of data;
• ii) determining a signal error from the filtered block of data;
• iii) updating at least one of said plurality of tap weights in said filter as a function of the determined signal error;
• and
• iv) repeating steps i, ii, and iii until a filter updating stop criterion is satisfied.