Phaser 6000/6010 and WC 6015 MFP Xerox Internal Use Only 2-61
Theory of Operation
Fax Standards (ITU-T Recommendations)
International FAX standards (ITU-T recommendations) include G1 to G4. G1 to G3
use analog telephone networks. G4 uses a digital telephone network (ISDN). G3 is
the standard currently in greatest use. FAXes conforming to Super G3, a recently
added standard, are equipped with a fast 33.6kps modem and reduce
transmission times to about half those of G3 FAXes.
Standard &
Year Issued
Minimum
Transmission
Time for
Single-Page
A4 Document
Maximum
Resolution
Maximum
Transmission
Speed Features
Group 1 (G1)
1968
Approx. 6 min. 100 x 100 dpi (Analog) Analog
transmission.
No band
compression.
Group 2 (G2)
1976
Approx. 3 min. 100 x 100 dpi (Analog) Analog
transmission.
Band
compression
technology
adopted.
Group 3 (G3)
1980
Approx. 1 min. 200 x 200 dpi 14.4 kbps
(Super G3:
33.6 kbps)
Connection to
analog line
using Fax
modem.
Image data in
digital format.
Data
compression.
Most common
standard in
use.
Group 4 (G4)
1988
Approx. 3 sec. 400 x 400 dpi 64 kbps
(using ISDN)
Digital
transmission.
Supported by
various digital
transmission
services.
Halftone
supported.
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