A communication device (104) comprises a receiver circuit (108) receiving a modulated receive signal. A reference oscillator (132) generates a first clock signal at a first frequency, the first clock signal having harmonics. Circuitry (130) coupled to the reference oscillator and to the receiver responds to the first clock signal to produce a signal used by the receiver to reduce the frequency of the modulating signal. A frequency spreading circuit (134) is also coupled to the reference oscillator to modulate the first clock signal with a frequency spreading signal to produce a modulated clock signal including modulated harmonic frequency components. The frequency spreading circuit selectively combines the frequency spreading signal and the first clock signal. A control circuit (114) controls the frequency spreading circuit to modulate first clock signal with the frequency spreading signal when the selected received signal includes a harmonic of the first clock signal.