Toshiba GD-1220, GD-1221 service manual 9600 bps, 7200 bps, 4800 bps, 2400 bps, Tcf

Models: GD-1220 GD-1221

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4)Training

The training is performed in the binary procedure to surely transmit the image signals.

-Training signal

The training signal is transmitted following the DCS signal at the modem speed specified by the DCS signal. Responding to this training signal, the receiving side adjusts the auto-equalizer.

-Format of the training signal 14.4 Kbps, 12 Kbps

 

Segment 1

Segment 2

Segment 3

Segment 4

 

 

 

 

 

 

 

 

 

 

Alternation

Equalizer

Chain-store

 

 

 

 

adjustment

information

Scrambled binary data “1”

 

TCF

 

of ABAB

 

 

pattern

sequence

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

106 msec

1240 msec

27 msec

20 msec

 

 

 

 

 

 

 

 

 

 

 

 

 

1393 msec

 

 

 

 

 

 

 

 

 

 

 

-9600 bps, 7200 bps

 

 

Segment 1 Segment 2 / Segment 3

Segment 4

 

 

 

 

 

 

 

 

 

 

V.29

 

No signal

Repeating 2-state

Scrambled data “1”

TCF

 

signal

 

 

 

 

 

 

 

 

 

 

(Binary)

(Hexa or octal)

 

 

 

 

 

 

 

 

 

 

 

 

20 msec

53 msec+160 msec

20 msec

 

 

 

 

 

 

 

 

 

 

 

 

 

 

253 msec

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

-4800 bps, 2400 bps

 

Segment 1Segment 2 Segment 3

Segment 4

Segment 5

 

 

 

 

 

 

 

 

 

Non-

 

Continuous

0° to 180°

 

 

 

 

180° phase

 

 

V.27ter

modulated

No signal

2-phase pattern

Scrambled data “1”

TCF

inversion

 

carrier

 

 

 

 

 

 

(Binary)

(Binary)

(Hexa or octal)

 

 

 

 

 

 

 

 

 

 

 

 

4,800 bps: 923 msec,

2,400 bps: 1158 msec

-TCF signal

An error may occur in the image data if the training is not performed correctly. The transmitting side sends a TCF signal and checks if any error occurs in image data before the image data communication to follow. When the receiving side detects an error in the TCF signal, it transmits an FTT signal to the transmitting side to request the retraining. When there is no error, the receiv- ing side transmits a CFR signal.

The TCF signal transmits all zeros for 1.5 seconds at the same modem speed as that for the training signal.

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GD-1220/1221

 

DIALING/COMMUNICATION CONTROL

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Toshiba GD-1220, GD-1221 service manual 9600 bps, 7200 bps, 4800 bps, 2400 bps, Tcf