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例一:有线电视用户有几个频道伴音杂声大,其它频道声音、图像都正常,经测量,每个频道信号电平在70dBμV左右,排除了因输入信号电平低引起伴音杂声大的可能性。手动微调电视机频道,伴音杂声仍然较大,排除了因调试不当引起伴音杂声大的可能性。后经检查发现该用户家进线并接了几根用户线到各个房间,导致电缆输入和输出阻抗不匹配,在某几个频道上引起声音和图像不同步。直接接通到电视机的用户线,或者用分配器连接几根用户线,故障排除。
Example 1: There are several channels of cable TV users with loud sound noise, other channel sound, images are normal, measured, the signal level of each channel is about 70dBμV, ruled out due to low input signal level caused by sound noise possibility. Manually fine-tuning the TV channel, the sound noise is still large, ruled out due to improper debugging sound the possibility of loud noise. After inspection found that the user home line and then pick up a few user lines to each room, resulting in cable input and output impedance mismatch, caused in a few channels on the sound and image are not synchronized. Directly connected to the TV user lines, or use the distributor to connect several user lines, troubleshooting.