Patent ID: 6928160

Claim:
In a telephone including an adaptive echo canceller having a finite impulse response filter and capable of cancelling echoes longer than filter length, the improvement comprising: said finite impulse response filter having less than 1024 taps; and a bulk delay estimating circuit that matches time intervals representing a signal with time intervals representing an echo of the signal for programming said finite impulse response filter; wherein the bulk delay estimating circuit includes: a first input for an undelayed signal; a first circuit for computing intervals in the undelayed signal; a second input for receiving a delayed signal; a second circuit for computing an equal number of intervals in the delayed signal; a subtracting circuit coupled to said first circuit and to said second circuit, said subtracting circuit subtracting corresponding intervals from each circuit to produce a plurality of differences; and a summation circuit coupled to said difference circuit, said summation circuit accumulating a net difference and providing an output indicating whether or not the net difference is less than a predetermined amount.