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我国中小城市和地广人稀的边远地区,空间电视信号场强一般较弱,这些地区的电视用户很想借助CATV系统来改善收看效果。在较大的城市,一般只能收看到本省市的节目,邻近省市的信号到达本地后亦成为弱信号。鉴于以上两种情况,我国的CATV系统依然存在着弱场强接收的突出问题。如何改善CATV系统中的弱信号接收传输分配的问题,具有一定的现实意义。为了改善上述问题,首先要强调以下几个基本概念的关系:即画面质量与输出电压信噪比的关系,系统信号电平(系统前端输入电平)与用户电平(系统终端输出电平)及放大
In China’s small and medium-sized cities and vast and sparsely populated remote areas, the signal strength of space television signals is generally weak. Television users in these areas would like to improve their viewing performance with CATV systems. In larger cities, programs in the province and municipality can only be seen in general. Signals from neighboring provinces and cities also become weak signals after they reach the local area. In view of the above two kinds of situations, our country CATV system still exists the outstanding problem that the weak field receives. How to improve the transmission and distribution of weak signals in CATV system has certain practical significance. In order to improve the above problems, we must first emphasize the relationship between the following basic concepts: the relationship between the picture quality and output voltage signal to noise ratio, the system signal level (system front-end input level) and user level (system terminal output level) And zoom in