09-05-2017, 08:37 PM
Opticalcommunications textbook PDF by author bakshi download
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optical communication pdf author by bakshi
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Opticalcommunications textbook PDF by author bakshi download
11-05-2017, 10:53 AM
Optical communication, also known as optical telecommunication, is remote communication using light to convey information. It can be done visually or by electronic devices. The first basic forms of optical communication go back several millennia, while the first electrical device created to do so was the photophone, invented in 1880.
An optical communication system uses a transmitter encoding a message in an optical signal, a channel that carries the signal to its destination and a receiver that reproduces the message from the received optical signal. When electronic equipment is not used, the "receiver" is a person who visually observes and interprets a signal, which may be simple (such as the presence of a light beacon) or complex (such as lights using color codes or showing A Morse code sequence).
Optical communication in free space has been deployed in space, while terrestrial forms are naturally limited by geography, climate and the availability of light. This article provides a basic introduction to the different forms of optical communication.
Visual techniques such as smoke signals, beacon fires, hydraulic telegraphs, ship flags and traffic lights were the earliest forms of optical communication. The traffic lights of the hydraulic telegraph date back to the 4th century BCE in Greece. Emergency lights are still used by seafarers in emergencies, while headlights and navigation lights are used to communicate the dangers of navigation.
The heliograph uses a mirror to reflect the light of the sun to a distant observer. [5] When a marker tilts the mirror to reflect sunlight, the distant observer sees flashes of light that can be used to transmit a pre-set signal code. Naval ships often use signal lamps and Morse code in a similar way.
Aircraft pilots often use visual approach slope indicators (VASI) to land safely, especially at night. Military aircraft landing on an aircraft carrier use a similar system to land properly on a transport deck. The colored light system communicates the height of the aircraft with respect to a standard landing slope. In addition, airport control towers continue to use Aldis lamps to transmit instructions to aircraft whose radios have failed.
At present, a variety of electronic systems transmit and receive lightly transported information optically. Fiber optic communication cables are now used to send the vast majority of electronic data and long-distance telephone calls that are not transmitted by radio, terrestrial microwave or satellite. Optical free space communications are also used daily in various applications.
An optical communication system uses a transmitter encoding a message in an optical signal, a channel that carries the signal to its destination and a receiver that reproduces the message from the received optical signal. When electronic equipment is not used, the "receiver" is a person who visually observes and interprets a signal, which may be simple (such as the presence of a light beacon) or complex (such as lights using color codes or showing A Morse code sequence).
Optical communication in free space has been deployed in space, while terrestrial forms are naturally limited by geography, climate and the availability of light. This article provides a basic introduction to the different forms of optical communication.
Visual techniques such as smoke signals, beacon fires, hydraulic telegraphs, ship flags and traffic lights were the earliest forms of optical communication. The traffic lights of the hydraulic telegraph date back to the 4th century BCE in Greece. Emergency lights are still used by seafarers in emergencies, while headlights and navigation lights are used to communicate the dangers of navigation.
The heliograph uses a mirror to reflect the light of the sun to a distant observer. [5] When a marker tilts the mirror to reflect sunlight, the distant observer sees flashes of light that can be used to transmit a pre-set signal code. Naval ships often use signal lamps and Morse code in a similar way.
Aircraft pilots often use visual approach slope indicators (VASI) to land safely, especially at night. Military aircraft landing on an aircraft carrier use a similar system to land properly on a transport deck. The colored light system communicates the height of the aircraft with respect to a standard landing slope. In addition, airport control towers continue to use Aldis lamps to transmit instructions to aircraft whose radios have failed.
At present, a variety of electronic systems transmit and receive lightly transported information optically. Fiber optic communication cables are now used to send the vast majority of electronic data and long-distance telephone calls that are not transmitted by radio, terrestrial microwave or satellite. Optical free space communications are also used daily in various applications.
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