Smart Proxmity Detector

I'm soldering a smart proxmity detector PCB. It uses a PICAXE-08 and will communicate with the robot it is attached to. The idea is that its PICAXE flashes two IR LEDs in sequence and looks for a sign of a reflection from the 40 kHz IR detector. The result is sent to the robot controller as a serial message. The PICAXE can operate the IR LEDs at a range of frequencies, allowing the proximity detector to estimate distances to obstacles. Since there are two IR LEDs, the proximity detector determines whether the obstacle is on the left, right, or both sides.