IBM International ISDN, Руководство пользователя

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Appendix C: A Brief ISDN Glossary
202 ISDN PC Card – 17 Appendix C: A Brief ISDN Glossary
Fax standards There are two important fax standards for ISDN:
•
G3 (Group 3, ITU standard T.4) which comes
from the analog telephony world and allows
a maximum resolution of 200 dpi by 200
dpi. Transfer speeds usually are 2,400 bps,
4,800 bps, 7,200 bps, 9,600 bps, and 14.4
kbps. The I BM I nternational I SDN PC Card
supports the fax G3 standard.
•
G4 (Group 4, ITU standard T.6) is a digital fax
standard which is only available in ISDN. It
allows a maximum resolution of 400 dpi by
400 dpi. Transfer speeds are 2,400 bps,
4,800 bps, 9,600 bps, 48 kbps, and 64
kbps. However there are hardly any G4 fax
devices on the market, and they are prohibi-
tively expensive. G4 stands for Group 4 (ITU
standard T.6).
Fossil Fido Opus Seadog Standard Interface Layer. This
is a modem emulation standard developed for an-
alog BBS communications. A FOSSIL driver sup-
ports most of the AT commands set used by ana-
log modems.
Hot insertion /
removal Denotes the installation or removal of a peripher-
al device when the system is powered on and run-
ning.
ISDN voltage The ISDN network voltage at the subscriber inter-
face, where the ISDN terminal equipment is con-
nected, is 40 VDC.
ITU International Telecommunication Union. A United
Nations body which develops recommendations
for international telecommunication standards.
kbps, kbit/s Kilobits per second. The data speed over an ISDN
B channel is 64 kbit/s, i.e. 64,000 bits per sec-
onds or 8,000 bytes per second.
Mbps, Mbit/s megabits per seconds One Mbit/s is 1,000,000
bits per second, or 125,000 bytes per second, or
roughly 122 kilobytes per second.
Glossary