GaAs laser voice communicator

Leelavathi, H and Veeraraghavalu, VM and Subrahmanyam, K and Pichamuthu, JP (1981) GaAs laser voice communicator. Technical Report. National Aeronautical Laboratory, Bangalore, India.

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In this report, the design and construction of a half-duplex laser communicator for use over short distances through line-of-sight atmospheric paths is described. The capabilities and limitations of optical communication systems are discussed in Chapter-! along with an outline of the work undertaken at NAL. The design of the optical transmitter using the GaAs laser as the source is described13; in Chapter-2. The technique of encoding the voice signal to suit the optical transmitter is discussed in Chapter-3. The adaptive delta modulation technique is best suited for this purpose and the adaptive delta modulation circuit is described. In Chapter-4 the different types of photo- detectors suitable for an optical receiver are briefly reviewed. An optical receiver designed around a Silicon PIN13; photo-diode is described. The method of recovery of the clock frequency from the received digital pulse stream is also outlined. In Chapter-5 the complete transceiver system comprising the transmitter, encoder and the receiver is described. The tests performed on the complete system using an audio signal and an actual signal over a 5-meter test oath are outlined.

Item Type: Monograph (Technical Report)
Uncontrolled Keywords: Optical communicators;Optical fibres;Infrared;Optical Communication
Subjects: CHEMISTRY AND MATERIALS > Composite Materials
CHEMISTRY AND MATERIALS > Chemistry and Materials (General)
Depositing User: M/S ICAST NAL
Date Deposited: 22 Dec 2006
Last Modified: 24 May 2010 04:24

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