Patent ID: 7595689

Claim:
A predistorter arrangement for linearising a distorting element, the predistorter arrangement comprising: a pilot generator that generates a composite signal comprising an input signal and only a single pilot signal having only one frequency component at a time, a predistorter that predistorts the composite signal to produce a predistorted signal which is supplied to an input of the distorting element, and an error corrector that (1) receives a feedback signal corresponding to an output signal generated by the distorting element in response to the predistorted signal, (2) detects, in the feedback signal, cross-modulation distortion signals derived from cross-modulation of the input signal on the single pilot signal within the distorting element, wherein the cross-modulation of the input signal on the single pilot signal within the distorting element means that modulation of the input signal results in modulation of the single pilot signal in the output signal generated by the distorting element, (3) produces an error correction signal based on the detected cross-modulation distortion signals, and (4) applies the error correction signal to the predistorter to adjust the predistortion of the composite signal by the predistorter to reduce the cross-modulation distortion signals in the output signal subsequently generated by the distorting element.