近年来,随着我国卫星电视事业和有线电视事业的飞速发展,用户通过有线电视收看的电视节目套数也越来越多,极大地丰富了广大有线电视网用户的业余文化生活。大家一致公认有线电视的图像和伴音信号远优于开路播放的无线电视信号。但是,也有很多用户反映他们的电视机收不全有线电视网上的所有节目频道。其实原因很简单,那就是这些用户的电视机不具备接收增补频道的性能。大家要问,什么是增补频道?我们知道,过去生产的电视机是为接收无线电视节目而设计的,无线电视所使用的频率范围是VHF1-12频道, In recent years, with the rapid development of China’s satellite television and cable television businesses, more and more television programs are subscribed to by cable television users, greatly enriching the amateur cultural life of cable television network users. It is unanimously accepted that the images and audio signals of cable television are far superior to those of wireless television signals broadcast in open circuit. However, there are also many users who have reported that all their TV channels are not available on cable networks. In fact, the reason is very simple, that is, these users do not have the TV to receive additional channel performance. We have to ask what is an additional channel? We know that television sets that were produced in the past were designed to receive wireless television programs. The frequency range used by wireless television is VHF channels 1-12,