Abstract: The present invention provides a novel method, device, digital signal processor and modem for efficiently determining and tracking a phase roll of a far end echo by utilizing a novel phase error generator and a novel, efficient replica generator. The efficient replica generator utilizes a uniquely positioned phase rotator to facilitate replication of the far end echo. A unique combination of a Hilbert phase splitter and a conjugate Hilbert phase splitter together with a rectangular to polar converter enable the novel phase error generator to provide a reliable phase error.

Abstract: A decision feedback equalizer is suitable for use with a bipolar return-to-zero receiver. The equalizer determines an output Y(n) (160) based on a compensated received value X(n) (104) and a correction factor, D(n) (141 ). After receiving X(n), the equalizer retrieves a stored value D(n) corresponding to the k prior output values Y(n-1), . . . , Y(n-k) from a memory device (140). The equalizer then forms an equalized received value X'(n) (107) based on combining X(n) with D(n). The equalizer then determines the output value Y(n) based on comparing X'(n) with a positive threshold, V1 and a negative threshold, V2. When Y(n) is determined to be zero, the equalizer adjusts the stored correction value D(n) by a predetermined value, .DELTA., based on whether X'(n) is positive or negative.

Abstract: A modem with nonlinear equalization (100) receives a signal (101) that includes linear and nonlinear distortion. The modem includes a multiplier (107) that frequency shifts the signal to form a baseband signal, which is then sampled by an A/D converter (114) to provide a complex receiver input sample, R(n). A first equalizer (117) equalizes R(n) to form a first equalized result (n). A nonlinear generator (129) forms .vertline.R(n).vertline..sup.2 R(n), which is then equalized by a second equalizer (133) to form a second equalized result (n). A summing device (121) combines the first equalized result (n) with the second equalized result (n) to form a composite equalized result (n). The modem includes a data recovery circuit (125) that determines a received signal point (n) based on the composite equalized result (n) and a predetermined constellation.