| 摘要 |
PURPOSE:To shorten time for a frequency change processing and to shorten muting time by calculating the difference of the frequency of another broadcasting station from the frequency of a broadcasting station under reception at present and setting SD wait time only for time in proportion to the difference. CONSTITUTION:The strength of an electric field from the broadcasting station under reception at present is level-detected 14, and the detection output is supplied to a controller microcomputer 9. The controller 9 monitors whether the detection output is lowered rather than a level set in advance or not, and when the strength of the electric field is lower than the set level more than for fixed time, a value subtracting the AF frequency of the broadcasting station broadcasting the same program from the frequency under the reception at present is calculated. Based on this value, the wait time of SD is calculated and the time of a timer is set. The controller 9 transmits the PLL output of the AF frequency to a front end 2 and outputs a command to a mute circuit 6 so as to mute an output from an MPX demodulation circuit 5, and the output of the circuit 5 is cut.
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