Gravity Digital IR Transmitter Module - 

Gravity digital IR transmitter module. Infrared transmitters are widely used as a means of wireless communication by remote controls for televisions and other electronic devices. Police, firefighters and ambulance drivers for example, carry a special IR transmitter that they can use to change traffic lights from red to green within two seconds as they approach an intersection. The main limitation of IR technology is that it requires line-of-sight between the transmitter and receiver. It cannot be used around corners or between rooms with intervening walls or ceilings.