Infrared Debugging

Today my infrared remotes stopped working properly. Maybe one command in a dozen would do anything, unless I was right up close to the IR receiver.

I have an IR receiver embedded in the wall of my family room, and it's wired to a repeater in my front closet where my components are, and each of those has an IR emitter on it. On the other side of the closet is the bedroom, and some of the components -- DirecTV DVR, PS3, AppleTV -- are connected (through a 4x2 HDMI selector) to the TVs in both rooms, so I have an additional IR receiver in the bedroom. Works great, but today, the IR performance was massively degraded.

I tried switching out the repeater, tried jiggling wires, did a bunch of testing ... nothing worked. Finally I removed the second receiver from the wiring, and everything went back to normal. I went into the bedroom and saw that a bright white envelope was directly in front of the IR receiver. Directly above the receiver was the red LED from the TV to indicate it was off. So it seems the red LED was reflecting off the envelope, back into the IR receiver, and causing just enough interference that I couldn't see it show up in the "talkback" LEDs on the emitters or receivers, but it was still preventing proper communication.

It reminds me a lot of the software debugging I've done over the years.