Fax Standards (Itu-T Recommendations) - Fuji Xerox DocuPrint M355df Service Manual

Chapter 10 Principle of Operation

10.6 FAX Standards (ITU-T Recommendations)

10.6 FAX Standards (ITU-T Recommendations)
International FAX standards (ITU-T recommendations) include G1 to G4. G1 to G3 use analog telephone net-
works. G4 uses a digital telephone network (ISDN). G3 is the standard currently in greatest use. FAXes con-
forming 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.
Year
Standard
Issued
Group1
1968
(G1)
Group2
1976
(G2)
Group3
1980
(G3)
Group4
1988
(G4)
Minimum
Transmis-
Maximum
sion Time for
Resolution
Single-Page
A4 Document
Approx. 6
100 x 100dpi
min.
Approx. 3
100 x 100dpi
min.
Approx. 1
min
(14.4kbps) 600 x 600dpi
Approx. 3 sec
(33.6kbps)
Approx. 3
400 x 400dpi
sec.
Table 10-1
Maximum
Transmission
Speed
-
(Analog)
-
(Analog)
14.4kbps
(Super G3:
33.6kbps)
64kbps
(Using ISDN)
10-14
Features
First standard.
Analog transmission.
No band compression
technology
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.