> Apparantly, up to 1.125MHz. Quite a bit higher than the Pronto/RC5000's 56KHz,
> but the question is does anything in a home theater use that high?

Pioneer's GUI control codes from a couple of years back used 1.125 MHz carrier. They got so much flack from the installers because IR relay systems wouldn't work that they've stopped using it. Current Pioneer equipment works fine with Pronto.

The other band that's higher than the usual 32-40 KHz (and RCA's 56 KHz remotes) is 455 KHz. Some of Sony's receivers use that band, the idea being that using a higher carrier allows the receiver to receive its own remote codes and send codes to control other equipment at the same time. That's the thinking behind Pioneer's use of 1.125 MHz carrier, too.

Just to clarify something. Pronto itself can only capture codes up to 56 KHz carrier, but is quite capable of transmitting codes with much higher carrier frequencies. From where it might obtain those codes I'll leave as a deductive exercise...