We have been doing preliminary EMC testing of our new board and we observed an issue with HDMI input.
During our testing, when we run stress test applications (CPU & Memory stress test, Video playing, Ethernet ping, USB Read/Write test, SD card Read/Write) and when all the cables (except HDMI input) are connected (Ethernet Cable, 2x USB cable, HDMI output cable, power cable), the board can easily pass FCC CLASS B.
However, when we start sending a video stream through HDMI video input, the board pass FCC CLASS A, but doesn't pass FCC CLASS B.
It is very interesting, that when we run ADV7610 in FREE RUN mode (so ADV7610 is sending data to CPU, but it is not receiving HDMI input), the board is just fine and we pass FCC CLASS B.
I attached pictures from our measurements.
I read the Elwoods discussion: ADV760 Pixel Bus causes radiated emission problems with 1080p60 Input.
Has someone else had EMC issue with HDMI input receiver or ADV7610 chip? How did you solve the problem?