| 摘要 |
PURPOSE:To prevent miscount of a counter and to enable normal channel selection operation, by providing a filter rejecting a low frequency interference signal other than the local oscillating frequency of an electronic tuner, between a detection circuit of an automatic channel selector and a surface acoustic wave element. CONSTITUTION:An automatic channel selector is provided with a surface acoustic wave element having an input/output terminal inputting and outputting the oscillated frequency of a local oscillator of a voltage control type of an electronic tuner, detection circuit detecting the output signal of the surface acoustic element, and counter counting the number of times of output signal of this detection circuit and discriminating the channel selection or channel number. A filter consisting of a coil 40 and a capacitor 41 is provided between a matching circuit 20 matching the output of the surface acoustic element of the channel device and a detection transistor TR31 constituting the detection circuit. This filter and the circuit 20 is coupled with a capacitor 26, low frequency interference signal other than the local oscillation number is rejected with the capacitor 26 and the filter, allowing to prevent the misoperation of the counter. |
