Canon FACSIMILE BASIC 2000 Service Manual page 237

6.3.4 Training/Pre-message response
By training, TCF is transmitted at the transmission speed by which images
are actually transmitted after the receive command to check whether or not
images will be transmitted without a transmission error occurring.
The pre-message response is a response that is transmitted by the receiver
that has received the receive command and training/TCF.
Calling Side (transmitter)
Training
This signal is for performing equalization on the MODEM when trans-
mitting at the image transmission speed, and is performed for success-
fully receiving the following TCF. (For details, see 6.5 Training)
TCF
This test signal transmits a constant signal at the transmission speed
used for sending the image before the actual image is transmitted to ver-
ify that it can be transmitted successfully.
This signal is a string of "0" and is transmitted for about 1.5 seconds.
CFR
This signal notifies the other party that TCF can be received normally
and that the receiver is ready to receive.
When there is a problem on either side, FTT is transmitted instead of
CFR. (See 6.5.3 When TCF cannot be successfully received.)
Training
TCF
Preamble
Fig. 5-69 Training/Pre-message Response
Transmission Reception
Transmission Reception
Transmission Reception
G3 FACSIMILE COMMUNICATIONS
Called Side (receiver)
CFR
Same modulation signal
as image signal
Same modulation signal
as image signal
Binary Signal
1
2
3
4
5
6
ït
çi
5–95