CCITT Groups 1-4

CCITT Groups 1-4
   A set of four standards for facsimile transmissions. Groups 1 and 2, which are no longer used, define analog facsimile transmissions. Groups 3 and 4 describe digital systems, as follows:
   • CCITT Group 3
   Specifies a 9600bps modem to transmit standard images of 203 dpi horizontally by 98 dpi vertically in standard mode, and 203 dpi by 198 dpi in fine mode.
   • CCITT Group 4
   Supports images up to 400 dpi for high-speed transmission over a digital data network (for example, ISDN), rather than over a dial-up telephone line.
   CCITT is now known as the International Telecommunication Union.

Dictionary of networking . 2014.

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