Cross-polarization canceler/equalizer

Claim 1

A cross-polarization equalizer/canceler for concurrently equalizing and canceling cross-polarization components in a first and a second orthogonally polarized digital signal, the equalizer/canceler comprising: a first and second input terminals for receiving the first and second orthogonally polarized signal, respectively; a first and a second straight-through path (21,22) coupled to the first and second input terminal, respectively; a tapped delay line matrix (20) comprising a separate tapped delay line (TDL) in each of the first and second straight-through paths and each of the first and second cross-over paths, each TDL including a plurality of complex taps which are individually responsive to control signals for appropriately changing a current tap setting and a resultant output signal of each TDL; a first adder means (32) for adding the output signals from the TDLs in the first straight-through path and the second cross-over path; second adder means (33) for adding the output signals from the TDLs in the second straight-through path and the first cross-over path; and tap adjusting means (29, 30) coupled to the output of the first and second adder means and to the complex taps of the TDLs in the TDL matrix for generating appropriate control signals to the complex taps of the TDL matrix for appropriately changing the tap settings to effect concurrent equalization and cross-polarization component convergence in each of the first and second orthogonally polarized signals at the output of the first and second adder means, respectively, the tap adjusting means generating the appropriate control signals to each of the complex taps as derived from the addition of an associated current complex tap signal and an updated gradient representative of a vector of the component of the associated TDL signal in accordance with the relationship ##EQU5## where E represents an average of the associated term; a n and b n are the n th complex data symbol of the first and second orthogonally polarized signals, respectively; z Hn and Z vn are the complex samples at time nT of the first and second orthogonally polarized signals, respectively, at the output of the respective first and second adder means; and c i ,j identify a TDL within the TDL matrix where i and j designate the input to output path, respectively, of the TDL and 1 and 2 indicate the respective first and second orthogonally polarized signals.