Receiver for satellite broadcasting service

摘要

In a receiver for satellite broadcasting service, a selected audio subcarrier is converted into an IF signal demodulated into a demodulated signal which is applied to a feedback voltage generating means which converts the applied signal into a feedback voltage at a voltage ratio corresponding to the maximum frequency deviation of the selected audio subcarrier. The feedback voltage is applied by an operational amplifier to a varactor diode in a voltage-controlled oscillator. The oscillation frequency of the voltage-controlled oscillator is therefore varied dependent on the frequency deviation of the selected audio subcarrier to cause the maximum frequency deviation of the IF signal from a frequency mixer to match the bandwidth of a bandpass filter.