| 摘要 |
<p>In a broadcasting satellite (BS) converter adapted to be connected to a BS tuner (14) and fed with a power supply voltage signal from the broadcasting satellite tuner, a receiver circuit (20) is controlled by a control circuit (22). The receiver circuit includes a mixer (30), a first local frequency oscillator (32L) for outputting a first local frequency signal to the mixer to thereby convert BS signals, included in a low frequency band, into intermediate frequency signals (BS-IF), and a second local frequency oscillator (32H) for outputting a second local frequency signal to the mixer to thereby convert BS signals, included in a high frequency band, into intermediate frequency signals (BS-IF). The control circuit includes a detector circuit (52) for detecting whether a band switching pulse signal is superimposed on the power supply voltage signal, and a selector circuit (38) for selectively driving only one of the first and second local oscillators (32L, 32H) in accordance with a detection result obtained in the detector circuit. The detector circuit includes a phase-lock loop circuit (60) for the detection of the band switching pulse signal.
</p> |
