In a conference, the image and voice are normal when debugging it before. The image distortion occurred in a video-conferencing. It cannot be changed to other conference site and has serious streaking.
The value of CRC is large.
The problem occurs at line. First, test the terminal by bit-error tester, and there are bit errors. So it is not terminal problem. Test the switch distribution frame, and bit error still exists. So it is not the interference among terminal lines. Testing up along transmission line,and we find that switch user board has been out of subscription validity period. Signal waveform is distorted and unsteady. Changing the user board and trouble shooting.
Switch user board is aging and unsteady, which leads image distortion.