Complex Allpass-based IIR Adaptive Notch filter for RFI Cancellation in VDSL systems

FERNANDO GREGORIO; JUAN COUSSEAU; TIMO LAAKSO

Antalya

Conferencia; 13th European Signal Processing Conference; 2005

Eurasip

A complex-allpass-based multiple notch IIR filter is proposedto suppress Radio Frequency Interference (RFI) thataffect VDSL systems. A notch filter realization based oncomplex allpass cascaded second-order sections is presentedand evaluated in this paper. Two different algorithms, usingthe Recursive Prediction Error (RPE) method and an alternative(similar to the Steiglitz-McBride) method, are proposedto update the adaptive notch filter coefficients. Simplestochastic gradient algorithms can be obtained using allpasscascaded second-order sections whose regressors are formedby orthogonal functions which is not the case for the conventionalcomplex cascade realization. Comparisons with othermultiple-notch realizations evaluating convergence rate andresidual interference levels are included. The novel structureusing the RPE method reaches the lowest residual interferencelevel with the fastest convergence rate. Furthermore usingthe novel techniques stability check is not needed, whichreduces their implementation complexity.