Efficient implementation of echo cancellers for ISDN applications

A computationally efficient echo tail canceller that is an adaptive version of an interpolated finite impulse response filter is proposed. The results obtained with this approach are compared to those obtained with an adaptive FIR direct-form echo canceller. It is shown that the proposed structure is very efficient in estimating the echo tail; it requires significantly fewer multipliers compared to the direct-form adaptive FIR. The proposed structure also maintains the low accuracy required by the direct-form adaptive FIR for the ISDN (integrated services digital network) 2B1Q receiver for most operations and requires only the basic FIR computations