Fm tone rejection

An interference rejection unit for at least partially rejecting a narrowband interferer from an input signal, the unit comprising: an interferer detector for detecting the phase of an interferer in the input signal; a signal generator for generating a cancellation signal in dependence on the phase detected by the interferer detector; and a signal combiner for combining the input signal with the tone cancellation signal to generate an output signal in which the interferer is at least partially cancelled from the input signal.