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随着有线电视蓬勃发展,节目套数越来越多,目前300HHz、450HHz、550MHz 系统邻频传输同隔频传输是完全不同的一种传输方式。所以,应对系统输出口有关的技术参数引起足够重视。1.系统输出口电平系统输出口电平是有线电视为适应用户电视机而制定的一个重要数据,国标规定了在 VHF 频段力57～83dbμv.如果低于57dbμv,在电视机屏幕上形成雪花干扰;如果高于83dbμv时,电视机本身非线性失真就会形成交扰调制。所以 CATV 系统输出口电平
With the booming development of cable television, the number of programs is increasing. At present, the adjacent frequency transmission of 300HHz, 450HHz and 550MHz systems is completely different from that of the inter-frequency transmission. Therefore, the output of the system should be related to the technical parameters caused enough attention. 1. System output level The system output level is a cable television to adapt to the user’s television and to develop an important data, the national standard provides for the VHF band power 57 ~ 83dbμv. If less than 57dbμv, forming a snowflake on the TV screen Interference; if higher than 83dbμv, the television itself nonlinear distortion will form a cross-talk modulation. So CATV system output level