Fuji Xerox DocuCentre SC2020 Service Manual page 698

DC SC2020
Version 1.1
6.6.5.4 V.8 Operation/Manual Send
Below is the flow for Manual Send at the Sending Terminal.
Figure 1 j0mf2720
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6.6.5.5 Troubleshooting of Super G3 Fax
As Super G3 Fax belongs to analog communication, its basic troubleshooting is the same as G3 Fax. As
differences exist due to the fast communication speed and the different communication procedure, trou-
bleshooting unique in Super G3 mode will be described.
Super G3 Fax can communicate up to a maximum speed of 28800bit/s with V.34 modem. With option, it
can communicate up to 33600bit/s.
As the conventional communication speed is 14400bit/s (V.17), to achieve high speed communication by
V.34, you have to perform data transmission of 2 times or above the conventional speed at one time.
Therefore, communication is affected by the quality of telephone line now more than before. Even with
telephone lines that can communicate without errors in 14400/9600bit/s, communication errors may
occur in Super G3.
Normal analog public lines have satisfactory frequency characteristics in 300-3400Hz zone. Even if
Super G3 communication sends or receives using the same remote party or telephone line, the commu-
nication speed may differ. This is because the speed is decided based on the line quality measured at the
sending side using the Probing feature performed in V.34 procedure, and when sending or receiving is
done in Super G3, the result from Probing is changed. That is, Super G3 mode cannot always communi-
cate at the highest speed (33600bit/s). Domestic Super G3 communication can achieve a speed of
21600bit/s and above in most cases.
The conventional Fax at 14400bit/s or lower uses half-duplex communication which sends the signal
alternately whereas Super G3 Fax is performed using full-duplex communication which has a different
communication procedure. In full-duplex communication, Fax from both sides will send signal concur-
rently and each side can monitor the signal of the remote party while sending its own signal. Therefore,
until now, the communication status can be verified by monitoring the sound of the line but Super G3
communication is unable to judge by the monitor sound. That is, when communication error occurs, pro-
tocol monitor analysis is required now more than ever, and the frequency in which the Traces between
the incoming and outgoing stations are compared increases.
Super G3 Troubleshooting Precautions
ECM: ECM is required in Super G3 communication. Set the ECM feature to OFF and communicate via
V.17/V.29(1400/9600bit/s) instead of V.34, even if Super G3 mode is available.
Communication Procedure: Super G3 communication procedure consists of V.8 and V.34 procedures.
V.8 procedure will determine the verification of Super G3 mode and the communication speed. Once the
V.8 procedure has completed, it will proceed to V.34 procedure and transmit image information via V.34
procedure. V.34 procedure has the same command names as G3 procedure (such as V.17/V.29) and
most of their protocol traces are the same, but as it uses full-duplex communication, its command trans-
mission speed is 1200bit/s.
General
6.6.5.4 V.8 Operation/Manual Send