Panasonic KX-F1200 Service Manual And Technical Manual page 58

KX-F1200
7-5. UNIT CAN COPY, BUT CAN NO[ IRANSMIT J RECEIVE LONG DISTANCE OR INTERNAIIONAL
COMMUNICATION
The following 2 causes can be considered for this.
1) Cause 1
The other party is executing automatic calling, the call has been received by this unit, and this time until response with a L;LU
or DIS signal has been too long. (In almost case, this unit detects CNG signal and can respond to CED or DIS.) (According to
the ITU-T (CCITT) standard, the communication procedure is stopped when there is no response from the other party within
35sec, so that the other party releases the line.)
Line Connection
Time
Ringing Time
(about 4 sec/ring)
4
Other party FAX
machine dial
about 2 sec
Voice FAX
Indentification
Time 6sec 3 sec 1 sec
Greeting Send Time CNG Sign DIS Signal
(max.16sec) Detect Time send
75 msec
Max 35 sec =,-
t
Other party
FAX machine
receive the
DIS signal.
(Cause and Countermeasure)
As shown in the above chart, the total handshaking time must be reduced, but because of the long distance connection and
linking of several stations, the line connection time can not be reduced. Accordingly, the following countermeasures should
be tried.
(A) The automatic reception bell number should be 1. (user parameter: code No. 8)
(B) The greeting recording time should be made as short as possible. (if possible, 8sec or less)
(C) As the count of 35sec is started directly after dialing or directly after the START button has been pushed for models with a
START button, the other party should be called manually, if possible, this unit be switched to FAX by__._button when the
greeting is heard, and then the START button should be pushed for FAX communication.
Another possibility is entry of two pauses at the end of the auto dial number of the transmission side, in this way, the start
time for the count can be delayed by 2 pauses (about 10sec).
(Note) For short greeting recording, the greeting button must be pushed to end the greeting recording.
2) Cause 2
Erroneous detection because of echo or erroneous detection because of an echo canceler.
FAX 1
J
Station 1
J FAX 2
s,
2 Line Type 2 Line Type
i
S2 iStation 2
#
ji
The sea bottom cable or satellite
communication path. (4 Line Type)
(Echo/Echo Canceler)
The signal from FAX1 reaches FAX2 via the stations 1 and 2, but the reflection signal at station 2 also returns via station 1
(echo). As the distance between station 1 and station 2 is long, the echo returns to FAX 1 max. 600msec after transmission,
so than there is the possibility that this signal is detected erroneously as the signal from FAX2 and that trouble is caused. In
the case of a normal call, there is also the possibility that the echo of the own voice will make the call difficult to understand.
For this reason, each station (station 1, station 2) attaches echo cancelers ($1, $2) in case of international lines or long dis-
tance lines. For the echo canceler, the level of the transmission signal from FAX 1 is compared with the level of the reception
signal from the FAX2, and when transmission signal is larger, $1 is closed, while $2 is opened when it is smaller. In other
words, with transmission from FAX1, $1 is closed and $2 is open, so that the echo
does not return to FAX1.
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