550型电视频道变换器的原理与设计

Principle and Design of 550 TV Frequency Channel Transformer

随着有线电视和卫星电视的开通，节目数量的不断扩大，尤其是增补频道的使用，使相当数量的电视机已不能适应现有电视节目的收看。而频道变换器是专门为有线电视系统设计的终端接收设备，它能覆盖有线电视网包括增补频道在内的６０个频道。利用频道变换器可准确地调到任一有线电视频道，并经频道变换器内的调制器变频到固定的频道（１频道，４９．７５ＭＨｚ）输出。该变换器中心是８０３１单片机，选台用数字频率合成。具有红外遥控，开关电视机电源，频道频率微调、定时自动关机、直呼、递增／递减、最后呼出等功能。本文简要介绍其原理与设计。

ith the opening of wired TV and satellite TV,the number of programs is gradually increased. But because of using additional channels,quite a few television can't received all present programs. The frequency channel transformer is a terminal receiver especially for wired TV system. It covers 60 channels of wired TV net, including additional channels.Using the frequency channel transformer, any wired TV channel can be obtained exactly,and is transformed the fixed channel output through the modulator in the channel transformer.The center of the channel transformer is 8031 single-chip computer.The choice of the channel is synthesized with digital frequency.