17-11-2012, 11:46 AM
TESTING OF FIBER OPTIC COMMUNICATION
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Objective:
The objective of this experiment is to test a 650 nm fiber optic analog and digital link.
Theory:
Fiber optic links can be used for transmission of digital as well as analog signals. Basically a fiber optic link contains three main elements, a transmitter, an optical fiber and a receiver. The transmitter module takes the input signal in electrical form and then transforms it into optical (light) energy containing the same information. The optical fiber is the medium, which takes the energy to the receiver. At the receiver light is converted back into electrical form with the same pattern as originally fed to the transmitter.
Transmitter:
Fiber optic transmitters are typically composed of a buffer, driver and optical source. The buffer provides an electrical connection and isolation between the transmitter and the electrical system supplying the data. The driver provides electrical power to the optical source. Finally, the optical source converts the electrical current to the light energy with the same pattern. Commonly used optical sources are light emitting diodes (LEDs) and Laser beam. Simple LED circuits for digital and analog transmissions are available.
The fiber optic link:
Emitter and Detector circuit on board form the fiber optic link. This section provides the light source for the optic fiber and the light detector at the far end of the fiber optic links. The optic fiber plugs into the connectors provided in this part of the board. Two separate links are provided.
The receiver:
The Comparator circuit, Low Pass Filter, Phase Locked Loop, AC Amplifier Circuits form receiver on the board. It is able to undo the modulation process in order to recover the original information signal. In this experiment, the trainer board is used to illustrate One-Way communication between digital transmitter and receiver circuits.