Satellite broadcasting converter, control circuit incorporated therein, and detector circuit used in such control circuit

摘要

In a broadcasting satellite converter adapted to be connected to a BS tuner and fed with a power supply voltage signal from the broadcasting satellite tuner, a receiver circuit is controlled by a control circuit. The broadcasting satellite converter comprises a receiver circuit including a mixer, and a plurality of local oscillators connected to the mixer to convert broadcasting satellite signals into intermediate frequency signals, and a control circuit that controls the receiver circuit. The control circuit includes a detector circuit that detects whether a band switching pulse signal is superimposed on the pulse signal, the detector circuit including a converting circuit that converts a frequency of the band switching pulse signal into an integrated value for the detection of the band switching pulse signal. The control circuit further includes a selector circuit that selectively drives one of the local oscillators in accordance with the integrated value obtained in the detector circuit.