| 摘要 |
<p>A radio receiver (102) receives on a selected one of a plurality of channels, at least one of which is a control channel having relatively continuous signal is transmitted thereon. A frequency synthesizer (122) includes a voltage controlled oscillator (VCO 124) and phase lock circuits (126), such as a phase detector (130), a reference oscillator (134), a programmable divider (128) and a loop filter (132). The VCO can be switched between the phase lock circuits and an automatic frequency control circuit (AFC 114), which is connected to the radio receiver. When the radio receiver is receiving a quality control channel signal, the VCO is coupled to the AFC circuit. When the radio receiver is tuned to a channel other than the control channel, the VCO is coupled to the phase lock circuits.</p> |
