Wow! You guys are great with all of your help.
What kind of cable box is it? Are you sure the cable box doesn't have a configurable unit number that would solve the whole problem?
The cable boxes are Pioneer Voyager and a Scientific Atlanta 3100. There are no 'unit number' switches on the box, and I don't see any way to set a device number through the menus. I have also googled this with no luck.
You said the LR remote is a Pronto. What's the BR remote?
The BR remote is also a Pronto.
I love johnsfine's idea about changing the frequency, then converting it back at the cable box. When I got home late last night and read all the posts I though I had come up with a great circuit based on this:
Distort the Pronto transmission frequency. Use a Sharp IR module (Radio Shack pn 276-137) to remove the distorted carrier. Then use a 555 clocking at the correct frequency ANDed with the clean IR data.
Looking at the Pronto data the second word for my learned cable box codes is is '0048'. If I am not mistaken this would indicate that the cable box IR carrier frequency is 72Khz
This idea was simple, elegant and did not require a microprocessor. Life was good until I woke up in the middle of the night and realized that this would solve the BR box control problem from the LR, but If I were in the LR controlling the local box the BR would receive the undistorted signal, remove the 72Khz carrier, then re add it. This of course would effect the BR box.
Is there a IR demodulator that won't pass 72Khz? The Sharp/RS unit says 38-40Khz but appears to demodulate the cable box remote just fine. Either I am mistaken about the carrier freq, or it has a much higher bandwidth then specified. If I can find a demodulator that has a very narrow bandwidth I can transmit the BR distorted frequency in its range, but the unmodified cable box IR signal won't pass through.
classicsat idea is interesting and worth exploring if I can't get the previous problem solved.
jon_armstrong I appreciate the idea, but this won't work for me for several reasons:
1. I am already using the IR/X10 system and have used all 16 addresses (actually I could use a few more).
2. The local equipment in each room is directly controlled through the built-in IR window int the equipment. The IR repeater system I have set up receive in room A and transmit in Room B, and vice versa.
Once again, all your help and ideas is greatly appreciated.