ADAPTIVE TRANSVERSAL EQUALIZER USING A TIME-MULTIPLEXED SECOND-ORDER DIGITAL FILTER

摘要

A second-order digital filter arrangement having output taps from each of two first-order subsections and a pair of adjustable gain devices connected at each tap is modified by providing reentrant connections around the entire filter and also its first-order subsections to perform the function of a nonrecursive multitap transversal equalizer. One of each pair of gain devices serves as a forward-feeding tap signal multiplier. The remaining one of each pair of gain devices serves as a correlator for tap and error signals to adjust the gain of a tap signal multiplier. Memories for storing output signals and updated tap gain coefficients are programmed on a time-division basis while message signals are being circulated through the digital filter subsections. The capability of reconversion to the recursive digital-filter form under program control is at all times preserved.