Patent ID: 7279972
Filing Date: 2007-10-09
Classification: H03F

Abstract:
1. Apparatus for controlling a predistorter, said predistorter being arranged to apply a predistortion to an input signal to signal handling equipment to counter memory-effect distortion in an output signal of said equipment, wherein said predistortion is at least partially defined by a function that includes a set of one or more parameters and the apparatus comprises adjusting means for adjusting said set to detennine how adjustments to said set change said distortion and control means for deploying an adjusted version of said set in said predistorter that reduces said distortion, wherein said predistortion is partly defined by a function of said input signal in which said set appears and said function shapes said predistortion by way of convolving an impulse response characteristic with another function of the input signal to produce a correction signal and subtracting from the correction signal the expectation value of said correction signal at the current value of said input signal in order to produce a difference signal that is used to produce the predistortion.