| 摘要 |
<p>A channel selector for a radio frequency receiver system including a phase locked loop frequency synthesizer for synthesizing a local oscillator frequency corresponding to a closely determined frequency to a transmitted signal of a desired receiving channel, a closed loop search tuning system for varying the local oscillation frequency to provide an automatic frequency control operation of the channel selector, and a control system for enabling either the phase locked loop frequency synthesizer or the closed loop search tuning system to operate so as to control the local oscillation frequency in dependence upon the presence or absence of a received transmitted signal.</p> |
