| 摘要 |
PURPOSE:To reduce the necessity of a noise preventing filter or the like and the restriction of power supply arrangement, to maintain the performance of a radio receiver and to simplify its constitution by selecting properly the switching frequency of a switching power supply. CONSTITUTION:A control part constituted of a microprocessor and executing the processing of an instruction from an operation part 8 and the formation of display data to be displayed on a display part 9 determines a frequency dividing ratio of tuning frequency and selects the optimum switching frequency by using the data of the frequency dividing ratio tuning band or tuning frequency. The switching frequency preventing receiving performance from bad influence is determined so that the switching frequency and its higher harmonic are not included in a receiving band. The number of switching frequency levels is determined by a tuning frequency range, channel separation, a receiving band, a switching frequency variable range, etc., and the plural switching frequency levels are switched by a variable frequency divider 2.
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