Laser audio transmitter and receiver

Abstract

Nowadays safe transmission of voice is required. Many losses occur due to the transmission medium. And hence in our project, in order to transmit the audio signal reliably and safely we are transmitting a voice signal through “Light amplification by stimulated emission of radiation”, and allowing the beam to be aligned itself. A transmitter/receiver structure was created that converts an audio signal that is provided by means of a regular 3.5mm audio jack. The transmitter broadcasts it through laser to the receiver. The receiver’s function is then to convert the original input signal back into audio as output. The receiver uses a servo motor that is positioned on the transmitter and is being controlled by a microcontroller in order to automatically line up the transmitter with the receiver and it can be rotated in its horizontal plane. The alignment is achieved by rotating the transmitter until it brings itself into line with the receiver and is also accomplished by the help of the photo detector circuit on the transmitter which responds to red laser light being emitted from the receiver. The transmitting laser is switched on after the transmitter examines over its entire range until it locates and detects the receiver. On the receiver’s plane the voice signal is taken up by a group of photodiodes. And as a result we get sound transferred that can’t be “overheard” by other surrounding devices and equipments. Audio transmission by way of hardware is accomplished following the alignment done via software. And hence the two tasks are mutually dependent.