Patent ID: 7079576

Claim:
A fractional-spaced digital equalizer comprising: a bank of register delay elements representing a data register bank that stores samples of an input distorted waveform; a switch (S 1 ) to control a portion of a joint intersymbol interference (ISI)-canceling and matched filter (MF) equalizer update associated with an intersymbol interference (ISI)-cancellation process; a bank of register elements representing equalizer feedforward (FF) weight register bank that stores equalizer (FF) weights coefficient values; a bank of multiplier elements used in forming inner products associated with both the (ISI)-cancellation and (MF) constraint updates; a bank of summing nodes used in forming inner products associated with both the (ISI)-cancellation and (MF) constraint updates; an (M: 1) commutation device to perform decimation to the symbol rate; an algorithm to form the error sequence associated with (ISI) cancellation; an algorithm to convert an (ISI) cancellation error signal into an adjustment signal needed to control an equalizer (FF) weight update in accordance with a criterion for (ISI) cancellation; an algorithm to update the contents of the equalizer (FF) weight register bank in accordance with first, the criterion for (ISI)-cancellation, and second, a (MF) constraint criterion; a bank of register elements representing the constraint register bank to store samples of the constraint waveform; an algorithm that generates samples of the constraint waveform; the constraint waveform used in forming the inner product associated with the (MF) constraint processing; a switch (S 2 ) to control that portion of the joint (ISI)-canceling and (MF) equalizer update associated with the (MF) constraint process; a parameter (β) representing the constraint level of the (MF) constraint update; a differencing node to subtract the orthogonality measure from the constraint level in order to form the constraint error; and an algorithm to convert the constraint error signal into an adjustment signal needed to control the equalizer (FF) weight update in accordance with the (MF) constraint criterion.