Radio transceiver, e.g. cellular telephone - generates frequency spreading signal to modulate clock reference frequency when received signal includes harmonic of clock signal

摘要

The radio transceiver includes receives (108) a communication signal on a selected channel. A reference oscillator (132) generates a master clock signal at a given frequency, with harmonics. A frequency synthesiser (130) divides the clock signal to produce a signal for demodulating the received signal. A frequency spreading circuit (134) is coupled to the reference oscillator and to the receiver circuit to modulate the clock signal in order to generate a frequency spread clock signal. The harmonic components of the frequency spread clock signal are spread over a frequency bandwidth greater than the channel bandwidth. A control circuit (114) selectively operates the frequency spreading circuit to modulate the clock signal when a received signal on the selected channel includes a master clock signal harmonic.