Board Thread:Questions and answers/@comment-30049823-20190909232421/@comment-30049823-20191114084846

Elliottw wrote:

A "learning" remote is only interested in the control sequences. It probably strips the OEM pulses, and substitutes its own when resending the command sequences. That way it would maintain its manufacturer compliance while mimicking other devices. Actually, I've been chatting with the developer of irplus on the subject, which inspired some further investigation. I think it's actually simpler (but weirder) than what you described above.

I tried to get the HTC phone to learn from the Disk Shot remote directly. I succeeded, but it was very difficult. I had to rapid-fire a single button VERY quickly to get the phone to acknowledge it.

But then... get this... the playback of that recording DID NOT WORK on the Disk Shot base!! A look at the raw XML that got recorded showed the same pattern with much faster timing. That is, 640s and 1200s instead of 1040s and 2080s for the on&off durations!

You've got an EE background yourself, and you saw the internals of that remote, so you're probably thinking what I'm thinking:  "Well, dum-dum, that poor capacitor couldn't get a full recharge when you were frantically rapid-firing the poor thing!"

Rewinding to the scenario that recorded WORKING signals, with 1040 and 2080 durations: that was the chinese learning remote recording the Disk Shot signal in a single, calm button press. Yeah, I then had to rapid-fire the chinese learning remote to make the HTC phone acknowledge it, but THAT hardware is apparently a lot more tolerant of rapid-firing and able to maintain the signal integrity AND timing, better than the original Disk Shot remote hardware can.

TL;DR The structure of the signal directly from the Disk Shot remote is identical to the recording of it played back through the chinese learning remote. But there are major differences in the timing of each device's output when you rapid-fire them. (That's not an issue in "normal use" scenarios; the rapid-firing is just a trick to make the HTC phone think a simplistic IR signal is more complicated than it really is)