1. An apparatus that includes a signal processing device, the signal processing device comprising: an analog-to-digital converter (ADC), said ADC having at least one analog input and at least one digital output; a first processor, said first processor for adaptively estimating at least one first parameter relating to the at least one analog input of said ADC, the at least one first parameter being estimated based, at least partly, on the at least one digital output of said ADC; a filter, said filter having an input coupled to the at least one digital output of said ADC and receiving the at least one first parameter, said filter including a plurality of coefficients that adapt to minimize a noise gain of said filter; and a second processor, said second processor for building concatenated indices from various time lags of the at least one digital output of said ADC.