| 摘要 |
PURPOSE: To provide a method capable of easily tuning the frequency of the frequency modulation acoustic carrier of a multi-channel acoustic transmission standard in a satellite television receiver by using existing circuit parts as many as possible. CONSTITUTION: A quadrature mixer (m), a channel filter F', a demodulator D, an acoustic stage (t) and a central control unit st are provided, the frequency of a heterodyne signal pair is changed stepwise and the pass band of the channel filter F' is switched to the band width of the 2-5 fold of a search and tuning frequency step by the central control unit. Also, the demodulator D is switched to amplitude demodulation by the central control unit st and the relative maximum value of amplitude is decided from an adjacent measurement interval by an end part value detector ex. The value is supplied to an evaluation device (w) and a display device S and allocation to the relating search and tuning frequency step is preserved by the central control unit st for the evaluation device (w) and the display device S.
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