Here's the transmitter mast with the front lens/cover of the housing removed. Inside we see an array of infrared LEDs.

Next remove the 4 Phillips screws. Two of the screws fasten the metal hinge to the back half of the housing (one is partially obscured by the hinge in the first photo).

The other two screws fasten the LED circuit board to the back half of the housing.

The third photo shows a closer view of some of the infrared LEDs. There are 12 LEDs in all. They emit no visible light - but did you know? the IR beam can be seen by most camcorders and digital cameras.

The LEDs transmit the audio signal using FM modulation of the IR beam. The carrier frequencies used are 2.3MHz for the left channel, and 2.8MHz for the right. The specification for maximum range is 9 meters.