Do you know what frequency the AIM beacon modulates at? I believe the carrier is 38KHz but it is a pulsed signal at a lower frequency? I have seen this to be ~5mS with other beacons...just wondering if you are detecting this pulse to validate the signal or just an "edge"...i'm worried direct sunlight would give a false trigger.
Do you have issues with direct sunlight and your PNA4602M or is that what the tic-tac box is for?
I'm going to try a pre-wired TV IR receiver that has a tinted lens and i'll post how this works.
I'd love to hear how your transmitter is coming along.