Fax Standards (Itu-T Recommendations) - Xerox Phaser 6128MFP Service Manual

Fax Standards (ITU-T Recommendations)

Phaser 6128MFP Service Manual
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 that is currently in use. Faxes conforming to Super G3, a recent added
standard, are equipped with a fast 33.6kps modem and reduce transmission times
to about half those of G3 Faxes.
Fax Standards
Minimum
Transmission
Time for
Single-Page
Standard A4 Document
Group 1 Approx. 6 min.
(G1)
Group 2 Approx. 3 min.
(G2)
Group 3 Approx. 1 min.
(G3)
Group 4 Approx. 3 sec.
(G4)
Maximum
Maximum Transmission
Resolution Speed
100 x 100 dpi (Analog)
100 x 100 dpi (Analog)
200 x 200 dpi 14.4kbps
(Super G3:
33.6kbps)
400 x 400 dpi 64kbps
(using ISDN)
Theory of Operation
Features
Analog
transmission.
No band
compression.
Analog
transmission.
Band compression
technology
adopted.
Connection to
analog line using
Fax modem.
Image data in
digital format.
Data compression.
Most common
standard in use.
Digital
transmission.
Supported by
various digital
transmission
services.
Halftone
supported.
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