An adaptive signal processing system (800) comprises a plurality of receiving elements (802a-n), a plurality of analogue to digital converters (ADC's) (806a-n) and a digital signal processor (808). Each of the receiving elements (802a-n) is arranged to receive an incoming signal and has an ADC (806a-n) connected thereto. Each ADC *(806a-n) is arranged to convert a first portion of respective incoming signal into a digital form at a sampling rate less than the temporal Nyquist rate of the incoming signal. The signal processing (808) means is arranged to calculate complex weighting coefficients to be applied to a second portion of the incoming signal using the digitized first portion of the incoming signals. A method of calculating complex weighting coefficients is also described.