We are planning to use the Beagle Bone black in a commercial product, We have designed a custom cape and put the whole thing inside an aluminum housing. The system has been sent off for EMC testing but unfortunately the testing lab has failed conducted emission. There where a lot of peeks but the following frequencies failed
180MHz
203MHz
228MHz
250MHz
288MHz
312MHz
372MHz
384MHz
396MHz
420Mhz
468MHz
480MHz
875MHz
1000MHz
To try and isolate the issues we’ve acquired a spectrum analyzer and a set of near field probes. From my testing with the near field probes It seems that most of the failed frequencies are coming from the beagle bone black.
I’ve noticed the 1000MHz and 250MHz peeks (which where the biggest) seemed to go when the Ethernet cable was is removed. Many of the other peeks seemed to match up with the peeks on the beagle bone black FCC report. (http://elinux.org/Beagleboard:BeagleBoneBlack#Regulatory_Compliance_Documents) The once that don’t also seem to go when the beagle bone is powered off.
The system sits inside an extruded aluminum housing and the end plates are actually PCBs with single plane of copper. So there is lot I can still do to tighten up the enclosure. Although based on the report I would have expected the BBB to pass outside an enclosure.
Has any one else had similar experience with the beagle bone black and EMC problems? And how did you solve them?