V.42bis (redirected from V42bis)

V.42bis

An ITU standard (1989) for modem data compression. It uses the BTLZ technique to achieve up to a 4:1 ratio. V.42bis implies the V.42 error checking protocol.

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(communications, standard)

V.42bis - An extension of the ITU-T V.42 standard modem protocol to included compression using a Lempel-Ziv related technique, which detects frequently occurring character strings and replaces them with tokens. This is similar to the Unix compress utility. Typical compression for text is 50% or better; with nearly 20% gain from synchronous conversion this gives reduces transmission time by almost 60%.