EMI issues: HDMI passed with sufficient margin at resolution of 720P @60Hz, failed at 1080P
Without the WiFi BM3301 and PCIe SSD extension board working, all other interfaces were able to pass EMI testing, and the OLDI was able to passe when we wrapped the FPC cables in the copper foil, as shown below. but the we've encountered the HDMI issues again:
- HDMI passed with sufficient margin at resolution of 720P @60Hz, failed at 1080P
- HDMI passed at resolution of 1080P when the display screen was turned off
At this point, adjusting the hardware design at this point will not be sufficient to resolve the HDMI issues, except for the potential improvement offered by changing the micro HDMI connector to a standard HDMI connector. Therefore, we would like to propose the following options to proceed with the certification:
- Proceed with FCC Class B certification with the HDMI at a resolution of 720P @60Hz, as was done previously for the BeaglePlay.
- Proceed with FCC Class B certification with the HDMI at a resolution of 1080P, but with the display screen turned off, as was done previously for the BBB.
- Proceed with FCC Class A certification, which is intended for product use in industrial environments and provides a 10dB greater margin compared to Class B, then HDMI is able to pass with sufficient margin at resolution of 1080P.
@jkridner Please let us know your thoughts on the proposed options and if you have any further questions or comments.