Delay insertion for echo cancellation, with echo supression, in a communication network

An apparatus for delay insertion for echo cancellation for communication in a selected frequency spectrum, the apparatus coupleable to an echo canceller having a predetermined time period capacity for echo cancellation, the apparatus comprising:

• a first down sampler, the first down sampler operative to down sample, by a factor M, a spectral portion of a reference signal to form a down sampled reference signal;
• a second down sampler, the second down sampler operative to down sample, by a factor M, a spectral portion of a combined signal to form a down sampled combined signal, wherein the combined signal includes an echo of the reference signal;
• an adaptive echo delay filter coupled to the first down sampler, the adaptive echo delay filter operative to determine a plurality of filter coefficients using the down sampled reference signal, each filter coefficient of the plurality of filter coefficients having a filter location;
• the adaptive echo delay filter further operative, when the plurality of filter coefficients have converged, to determine a maximum filter coefficient of the plurality of filter coefficients and to determine a corresponding maximum coefficient filter location;
• and
• an adaptive delay inserter coupled to the adaptive echo delay filter, the adaptive delay inserter operative, when an echo delay time period is greater than the predetermined time period capacity for echo cancellation, to insert the echo delay time period prior to echo cancellation, the echo delay time period formed as a product of the corresponding maximum coefficient filter location and the down sampling factor.

An apparatus for delay insertion for echo cancellation for communication in a selected frequency spectrum, the apparatus coupleable to an echo canceller having a predetermined time period capacity for echo cancellation, the apparatus comprising:

• a first bandpass filter for filtering a reference signal in a selected sub-band of the selected frequency spectrum to provide a spectral portion of the reference signal;
• a first down sampler coupled to the first bandpass filter, the first down sampler operative to down sample, by a down sampling factor, the spectral portion of the reference signal to form a down sampled reference signal;
• a second bandpass filter coupled to the second down sampler, the second bandpass filter for filtering a combined signal in the selected sub-band of the selected frequency spectrum to provide a spectral portion of the combined signal, wherein the combined signal includes an echo of the reference signal;
• a second down sampler coupled to the second bandpass filter, the second down sampler operative to down sample, by the down sampling factor, the spectral portion of the combined signal to form a down sampled combined signal;
• an adaptive echo delay filter coupled to the first down sampler, the adaptive echo delay filter operative to determine a plurality of filter coefficients using the down sampled reference signal, each filter coefficient of the plurality of filter coefficients having a filter location;
• the adaptive echo delay filter further responsive to an error signal formed as a difference between an output of the adaptive echo delay filter and the down sampled combined signal;
• the adaptive echo delay filter further operative, when the plurality of filter coefficients have converged, to determine a maximum filter coefficient of the plurality of filter coefficients and to determine a corresponding maximum coefficient filter location;
• an adaptive delay inserter coupled to the adaptive echo delay filter, the adaptive delay inserter operative when an echo delay time period is greater than the predetermined time period capacity for echo cancellation, the echo delay time period determined as a product of the corresponding maximum coefficient filter location and the down sampling factor, to insert the echo delay time period prior to echo cancellation;
• and
• an echo suppressor coupled to the adaptive echo delay filter, the echo suppressor operative to provide echo suppression, following an insertion of the echo delay time period, until a convergence of a plurality of echo cancellation coefficients.