Toshiba DP120F Service Manual page 576

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>
Segment 1
Alterations
of
ABAB
106 msec.
<9600 bps, 7200 bps>
Segment 1
V29 No-signal
20 msec.
<4800 bps, 2400 bps>
Segment 1
Non-
V27ter
modulated
Carrier
• 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.
DP120F/DP125F Dialing and Communication Procedure
Segment 2
Equalizer
Condition
Pattern
1240 msec.
1393 msec.
Segment 2, Segment 3
Repeating two state signals
(Binary)
50 msec. + 160 msec.
253 msec.
Segment 2 Segment 3
Continuous 180°
No-signal
Phase Inversion
(Binary)
4800 bps: 923 msec.
2400 bps: 1158 msec.
Segment 3
Rate
Scrambled Binary
Pattern
27 msec.
Segment 4
Scrambled
Data "1"
(Hexa or Octal)
20 msec.
Segment 4
0° to 180° two-
phase pattern
(Binary)
9-12
Segment 4
Data "1"
20 msec.
TCF
Segment 5
Scrambled
Data "1"
(Hexa or Octal)
March 2000 © TOSHIBA TEC
TCF
TCF