Hoo boy, this brings back (bad) memories of emissions testing HDMI. Back in the days when I worked in consumer audio, we were working on a small sound bar that

Hoo boy, this brings back (bad) memories of emissions testing HDMI. Back in the days when I worked in consumer audio, we were working on a small sound bar that used HDMI for sound transmission via ARC. However, the product folks were worried about compatibility with SPDIF only TVs, so asked us to design a little HDMI to SPDIF dongle to allow this soundbar to work with SPDIF TVs, or HDMI TVs with no ARC support. Long story short: the compliance test folks were only testing with the SPDIF/ARC dongle. Due to a quirk of this (I think not being able to read an EDID from downstream?), the processor would shut off the HDMI interface. No TMDS, this; little to no emissions. We all got a nasty surprise when we hooked it up to a monitor and ran it in the test cell again. That was a big scramble to fix. Funnily enough, it was only at the highest bitrates (which I think was 1080p) that emissions were problematic. All the lower bitrates passed with no difficulty.