| 摘要 |
Sound detection apparatus for television signals of the L-SECAM system a tuner (1) for mixing television signals of the L-SECAM system with an upper oscillation wave and for outputting a video carrier and a colour subcarrier of the VHF low band, the VHF high band, and the UHF band. The band of intermediate frequencies of the video carrier and the colour subarrier are matched with each other. The intermediate frequency of a sound carrier of the VHF low band is different from the intermediate frequency of a sound carrier of the VHF high band and the UHF band. The apparatus includes a sound intermediate frequency filter (9) having a central frequency of a passing band which can be changed over between an intermediate frequency of the sound carrier of the VHF low band and an intermediate frequency of the sound carrier of the VHF high band and the UHF band. The apparatus also includes a sound detecting circuit (14) having a tank circuit (17) for detecting and outputting sound signals according to a psuedo synchronous detection method. The tank circuit (17) has a resonance frequency which can be changed over between an intermediate frequency of the sound carrier of the VHF low band and an intermediate frequency of the sound carrier of the VHF high band and UHF band. <IMAGE>
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