Panasonic KX-FP80C, Service Manual

Page: 67 / 240

OFF, the transmission side will try the training signal three times at each speed (9600BPS,
4800BPS and 2400BPS). If NG, it will drop the speed by one rank (fall-back). When the
international mode is switched ON, each speed will be tried only twice. In other words, the slower
speed with fewer errors can be accessed more easily. This is done because the line conditions
may deteriorate and the picture may be disturbed more easily during communication for
international lines or long distance communication, even when the training is OK. The default
value is ON as preference is given to clearer pictures rather than speed.
(Cause B)
The echo canceler operation stops with a 2100Hz signal. (i.e. S1 and S2 become ON).
Accordingly, when FAX1 has executed automatic reception, a CED signal is output. If this signal
is 2100Hz, S1 and S2 will become ON. Then the echo of the DIS signal output afterwards may be
received and FAX1 may execute an erroneous operation, preventing communication from
starting.
(Countermeasure B)
In the service mode, the CED signal frequency is set to 1100 Hz (code No.520), or the time setting
between the CED signal and the DIS signal is set from 75 msec to 500 msec in the service mode
(code No.593). This is because the echo canceler operation stop mode is canceled by an interval
of 250 msec or more. / Reduce receiving sensitivity to reduce the effect of RCV echo signal.
(Service mode: code No. 598)
(Cause C)
This model is FAX1 and the other party is FAX2.
For transmission from this model to FAX2, FAX2 executes automatic reception and transmits a
CED signal (2100 Hz) followed by a DIS signal. As the echo cancelers stops as described in cause
B, the echo of the DIS signal returns to FAX2. On the other hand, this model detects the DIS
signal and transmits a DCS signal. In other words, it is possible that the echo of the DIS signal
and the DCS signal transmitted from this model reach FAX2 one after the other. FAX2 detects an
error and communication does not start.
(Countermeasure C)
When the international DIS detection setting is set in the service mode (code No.594), this model
does not respond to the first DIS signal and returns a DCS signal only for the second DIS signal.
In other words, there is an interval of 250 msec between transmission of the first and second DIS
signal so that the echo cancelers operation recovers. An echo is not generated for the second
DIS signal.
Note:
When the other FAX does not respond with a DCS signal after DIS signal transmission, the DIS
signal is transmitted three times for trial.
Summary:
Symptom/Countermeasure Table (Long distance and international communication operations)
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