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URL:
http://www.itu.int
The ITU-T developed a series of modem standards,
prefaced by letter “V” (e.g., V.22, V.25, V.32, V.33, V.34, V.42, V.90), that
are fairly mature. These standards vary on parameters such as
synchronous/asynchronous transmission, 2-wire/4-wire, half/full duplex, error correction and data compression abilities. They provide data
rates of 4.8 to 56 kbps. V.34, one of the more commonly used standards,
provides up to 28.8 kbps and falls back to lower speed
for compatibility. V.90, the latest modem standard, provides a rate of up to 56
kbps.
Keywords:
physical layer, serial, Modem, high reliability, high speed,
Compression, Error correction.
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