Colibri iMX 7D 1GB SOM radiated emission high at 75MHz. FCC compliance failed

We have developed a carrier board using Colibri iMX 7D 1GB. Functionally the board works fine. But during radiated emission test, the board found to be radiating at 75MHz. After much analysis, it is concluded that the radiation is coming from SOM module.
We have tried to look into details of the SOM circuit, but could not locate the exact source for the radiation. We have some doubt around on-module Ethernet PHY. It may be the cause for radiated emission.
We need support for reducing the radiated emission so as to pass FCC compliance.

EThernet PHY is using 50MHZ clock. Were you able to find a location of 75MHZ radiation on module? Could you also ist all peripherals located on your carrier bard? Which display interface you are using if any?

Thank you alex.
We are not able to locate exact source of radiation. Below peripherals are present on board, although most of them remained unused during the Raditaion testing. We are not using any display.

  • USB
  • Ethernet (using on module PHY)
  • Ethernet (using external PHY KSZ8041 with PoE circuit)
  • uSD Card interface using SDIO interface
  • WiFi / Bluetooth module ATWILC3000 (Connected using SPI interface)
  • Two half duplex RS485 interface
  • Isolated DC/DC IL0505 for powering isolated RS485
  • Calender RTC with battery

Do you have any display(s) ? Could you please specify BSP version and software you are running on the module?

Hi @ksameer17,

Can you please let us know if you are able to further progress on issue? Are you still facing issue or if this is resolved?

Best Regards
Ritesh Kumar