Analog Transmission .pdf 45284c

Analog transmission Analog transmission is a transmission method of conveying voice, data, image, signal or video information using a continuous signal which varies in amplitude, phase, or some other property in proportion to that of a variable. It could be the transfer of an analog source signal, using an analog modulation method such as frequency modulation (FM) or

amplitude modulation (AM), or no modulation at all. Some textbooks also consider band data transmission using a digital modulation method such as ASK, PSK and QAM, i.e. a sinewave modulated by a digital bit-stream, as analog transmission and as an analog signal. Others define that as digital transmission and as a digital signal. Baseband data transmission using line codes, resulting in a pulse train, are always considered as digital transmission, although the source signal may be a digitized analog signal.

Descriptions Modes of transmission Analog transmission can be conveyed in many different fashions: fiber-optic cable twisted-pair or coax cable Via air Via water There are two basic kinds of analog transmission, both based on how they modulate data to combine an input signal with a carrier signal. Usually, this carrier signal is a specific frequency, and data is

transmitted through its variations. The two techniques are amplitude modulation (AM), which varies the amplitude of the carrier signal, and frequency modulation (FM), which modulates the frequency of the carrier.[1]

Types of analog transmissions Most analog transmissions fall into one of several categories. Until recently, most telephony and voice communication was primarily ana nature, as was most television and radio transmission. Early telecommunication devices utilized

analog-to-digital conversion devices called modulator/demodulators, or modems, to convert analog signals to digital signals and back.

Benefits and drawbacks The analog transmission method is still very popular, in particular for shorter distances, due to significantly lower costs and complex multiplexing and timing equipment is unnecessary, and in small "short-haul" systems that simply do not need multiplexed digital transmission.[2] However, in situations where a signal often has high signal-to-noise ratio and cannot

achieve source linearity, or in long distance, high output systems, analog is unattractive due to attenuation problems. Furthermore, as digital techniques continue to be refined, analog systems are increasingly becoming legacy equipment.[2] Recently, some nations, such as the Netherlands, have completely ceased analog transmissions (analogue switchoff) on certain media, such as television,[3] for the purposes of the government saving money.[4]

See also

Analog television Analog to digital converter Modulation Signal

References 1. The Froehlich/Kent Encyclopedia of Telecommunications By Allen Kent, Froehlich E. Froehlich.1991 Marcel Dekker. ISBN 0-8247-2900-5 2. Telecommunication System Engineering By Roger L. Freeman.2004 John Wiley and Sons. ISBN 0-471-45133-9 3. Netherlands Ends Analog Transmission Goodbye antenna, hello digital... -

dslreports.com 4. https://www.nytimes.com/aponline/technol ogy/AP-Netherlands-TV.html? _r=2&oref=s&oref=s

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