DECT echo control on the Texas Instruments BBSP

The BBSP echo canceller is based around an adaptive Transversal FIR filter predictor, which is adapted using a normalised version of the Sign(Data)*Error adaption technique. The BBSP can perform a Sign(Data)*Error or Data*Sign(Error) algorithm in the time taken by other microprocessors to perform the less efficient Sign(Data)*Sign(Error) adaptive prediction algorithm. A block diagram showing how an echo canceller fits into a communications system is presented. The echo suppression uses an asymmetric IIR filter with built-in hangover to provide fast suppression at the start of speech but maintain suppression for several mS after the end of speech