Super G3 Fax - Xerox WorkCentre Pro 423 Service Manual

WorkCentre Pro 423/428

2.3.3 Super G3 Fax

2.3.3.1 Super G3 Fax
In 1996, ITU-T recommended Super G3 Fax.
Super G3 Fax featuring 28.8 kbps communication has the modem capabilities of V.8 and
V.34. The protocol consists of V.8 and V.34 and optionally supports 33.6 kbps. Super G3 Fax
enables a fax to communicate with models of other manufacturers and also with the
conventional 14.4 kbps and 9600 bps faxes.
l Super G3 Fax communication is recorded as SG3 in the mode column of a report.
l Super G3 Fax transmits image information in Error Correction Mode (ECM).
l V.34 is a standard for modems from 28.8 kbps (optionally, 33.6 kbps) to 2400 bps.
Prior to the V.34 standard, V.8 prescribes a procedure for selecting optimum mode
according to the line status.
For communication with the conventional faxes as well as V.34 (28.8 kbps) ones, Super G3
Fax has also the capabilities of V.17 (14.4 kbps) and V.29/V.27ter (9600/4800 bps). The V.8
standard prescribes a procedure for checking the line status and selecting an optimum speed.
l V.34 does not use the TCF signal in phase B.
l In V.34, the command (NSF, DIS, and other) speed for the conventional procedure
section is 1200 bps.
2-106
03/02
Sample Protocol (T.30) Trace of Super G3 Fax
LOCAL
Dial
Termination
CNG
CM
V.8
CJ
[V34ph2]
[V34ph3]
V.34
[V34ph4]
Phase B
NSS
TRN
TRN
Phase C
CPIX
CPIX
PPS.EOP
Phase D
DCN
Phase E
*Phases B to E belong to the facsimile
procedure.
The V.34 modem has a command channel (low-
speed channel for NSF, DIS, and other
commands) and a primary channel (high-speed
channel for image and training signals).
CHAPTER 2 TROUBLESHOOTING
Level 2 Troubleshooting
Signal names and contents
REMOTE
Calling (CNG) signal: To indicate a communication function,
the local terminal sends this signal continuously until the
ANSam signal is received. This signal is not recorded in trace
data.
For manual transmission, a terminal sends "CI" as the V.8
ANSam
calling signal.
Also if the protocol enters phase B without detecting ANSam
JM and DIS V.8 capability is enabled (bit 6=1), the origination
side sends CI and returns to the V.8 procedure in Super G3
mode.
ANSam (response signal): The fax stops after sending a 2100
Hz signal modulated by 15 Hz for 4 continuous seconds or
when CM is detected. If the fax does not support Super G3
mode, CED is detected.
Call menu (CM) signal: This 300 bps signal (*) declares
modem mode available at the local terminal.
NSF Common menu (JM) signal: This 300 bps signal (*) declares
modem mode available at the local and remote terminals and
DIS
stops when CJ is detected. (For the FIFs of the CM and JM
signals, see No.2 "V.8 CM/JM Signal.")
CFR
CM end (CJ) signal: This 300 bps signal indicating JM check
and CM end is a three-octet string of 0.
V.34 Phase 2 (ph2): Probing
The line characteristics are measured using the probing
MCF
signal.
V.34 Phase 3 (ph3): Equalizer training
The modem equalizer is set using the TRN signal.
V.34 Phase 4 (ph4): Final training
The signal speed is determined.
(V.34 Phase 1 means the V.8 procedure.)
The modems of the local and remote terminals automatically
execute this section (Phases 2 to 4) to determine the send
level, equalizer, and modulation speed. The values
determined here have priority over the NSF/DIS contents.