PHASE LOCKED LOOP TUNING SYSTEM

摘要

The system includes a prescaler for dividing the frequency of the local oscillator signal by some factor. This factor is selected to make the resultant frequency divided signal compatible with digital process of the tuning system. A frequency selective network is coupled to the prescaler to tune the self-oscillation frequency of the prescaler to a frequency not corresponding to the local oscillator frequency of any legitimate channel. A new channel is selected and the amplitude of the local oscillator signal is compared with the threshold at which the prescaler will respond to it.