Group 3 Facsimile: The mode of black and white facsimile operation , defined in ITU-T Recommendation T.4, that incorporates means for reducing the redundant information in the signal by using a one-dimensional run -length coding scheme prior to the modulation process. Note 1: A 216 ª 279-mm document, i.e. , an 8½ ª 11-inch document, may be transmitted in approximately 1 minute or less over a telephone -type circuit with twice the Group 2 horizontal resolution . The vertical resolution may also be doubled. Note 2: Group 3 Facsimile machines have integral digital modems. Note 3: An optional two-dimensional bandwidth compression scheme is also defined within the Group 3 Facsimile Recommendation. Note 4: When any CCITT or CCIR Recommendation is modified by the ITU-T, the modified document is designated as an ITU-T Recommendation.
Group 3C Facsimile: The Group 3 digital mode of facsimile operation defined in CCITT Recommendation T.30. Note: Group 3C is also referred to as Group 3 Option C or as Group 3-64 kb/s.
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