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我区在采用7频道50瓦差转机进行转播后,对11频道图象产生网纹干扰,使转播台附近用户的电视图象干扰更为严重。经分析干扰是由于差转机本振辐射所引起的。11频道频率范围为207兆赫～215兆赫,而7频道的本振频率为213.25兆赫,正好落入11频道频率范围中。本振辐射进入电视接收机后与机内有用的本振频率混频产生一个不需要的中频信号,经放大在图象检波处分别与图象中频,色度中频和伴音中频差拍,检波出干扰视频,因此在电视屏幕上呈现出随本振频率漂移而移动的网纹。
My area in the use of 7-channel 50-watt differential transfer machine for broadcast, the network 11 of the image interference occurs, so that users near the retransmission station television image interference more serious. The analysis of interference is due to the local oscillator caused by poor radiation. Channel 11 has a frequency range of 207 MHz to 215 MHz, while channel 7 has a local oscillator frequency of 213.25 MHz, falling just below the channel 11 frequency range. After the local oscillator radiation into the television receiver and useful local oscillator frequency mixing to produce an unwanted IF signal by the image detection at the image IF, color IF and audio IF beat, detected Interfere with the video, and therefore appear on the TV screen moving with the frequency of the local oscillator network texture.