| 摘要 |
PURPOSE:To use a channel selecting circuit common to plural channel selecting circuits and to simplify circuit constitution by providing nonvolatile memories corresponding to tuner units and storing channel selection voltages in the memories selectively. CONSTITUTION:By the specification of a commander 5, a tuner unit 3A among 3A-3C is selected and the output of a local oscillator 34A is led out alternatively through a switch circuit 41. The signal is frequency-divided previously by a prescaler 45 and frequency-divided at a frequency division ratio corresponding to a specified channel by a programmable counter 46 to have a specific frequency fP; and a phase comparator 47 makes a phase comparison between the output of a reference oscillator 48 and a signal obtained by frequency division 49. The output of the comparator 47 is converted by an A/D converter 51 into a digital signal, which is stored in a nonvolatile memory 53A through a gate 52A. The data stored in the memory 53A is D/A-converted by a converter 54A into an analog signal, which is supplied as a channel selection voltage to the oscillator 34 and an RF tuner 31A through an adder 55A to be used for selecting a desired channel. |
