A method of splitting a signal (10) into two parts (10'', 10') is disclosed together with signal processing circuitry (22) for the same. The method comprises the steps of derotating the signal (10) whereby the frequency band of the derotated signal overlaps zero frequency; and splitting the derotated signal into two parts, a first signal part (10'') consisting substantially of positive frequency signal components and a second signal part (10') consisting substantially of negative frequency signal components. Also disclosed is methods, incorporating such a method of splitting a signal, for identifying the presence of in-band interference (11) in a signal and for despreading a spread spectrum signal.