Toshiba DP120F, Service Manual

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DP120F/DP125F Dialing and Communication Procedure 9-12 March 2000 © TOSHIBA TEC
2.2.4 Training
The training signal involves a pre-determined picture signal which is used to check the capabil-
ity of the phone line to reliably support facsimile traffic.
• Training signal
The training signal is transmitted following DCS with the modem speed to be selected by
DCS. At the receiving station, the automatic equalizer is adjusted by the training signal.
• Format of the training signal
<14.4 K bps, 12 K bps>
<9600 bps, 7200 bps>
<4800 bps, 2400 bps>
• TCF signal
When training is not performed correctly, an error may occur in the picture signal. The Tx
station transmits a TCF signal and checks if any error occurs in picture data before the
picture data communication to follow. When the Rx station detects an error in the TCF
signal, the Rx station sends an FTT signal to theTx station and request for re-training. When
normal, a CFR signal is sent instead.
The modem speed of TCF signal is the same as the training signal, and it transmits all zeros
for 1.5 seconds.
Segment 1
Segment 2 Segment 3 Segment 4
Alterations
of
ABAB
Equalizer
Condition
Pattern
Rate
Pattern
Scrambled Binary
Data "1"
TCF
106 msec. 1240 msec. 27 msec. 20 msec.
1393 msec.
Segment 1
Segment 2, Segment 3
Segment 4
20 msec. 50 msec. + 160 msec. 20 msec.
253 msec.
V29
No-signal
Repeating two state signals
(Binary)
Scrambled
Data "1"
(Hexa or Octal)
TCF
Segment 1
4800 bps: 923 msec.
2400 bps: 1158 msec.
V27ter TCF
Non-
modulated
Carrier
Continuous 180°
Phase Inversion
(Binary)
0° to 180° two-
phase pattern
(Binary)
Scrambled
Data "1"
(Hexa or Octal)
No-signal
Segment 2 Segment 3 Segment 4 Segment 5