Wsw 20 Overseas Communications Mode Setting - Brother MFC8440D Service Manual

7/13/2019
Selector
No.
1
2
3
4
5
6
7
8
Selector 1:

Setting this selector to "1" makes the machine transmit a 1700 Hz echo protection (EP) tone
immediately preceding training in V.29 modulation system to prevent omission of training
signals.
Prefixing an EP tone is effective when the machine fails to transmit at the V.29 modem speed
and always has to fall back to 4800 bps transmission.
Selectors 2 and 3: Overseas communications mode

These selectors should be used if the machine malfunctions in overseas communications.
According to the communications error state, select the signal specifications.
Setting selector 2 to "1" allows the machine to use 1100 Hz CED signal instead of 2100 Hz in
receiving operation. This prevents malfunctions resulting from echoes, since the 1100 Hz
signal does not disable the echo suppressor (ES) while the 2100 Hz signal does.
Setting selector 3 to "1" allows the machine to ignore a DIS signal sent from the called station
once in sending operation. This operation suppresses echoes since the first DIS signal
immediately follows a 2100 Hz CED (which disables the ES) so that it is likely to be affected
by echoes in the disabled ES state. However, such a disabled ES state will be removed soon
so that the second and the following DIS signals are not susceptible to data distortion due to
echoes. Note that some models when called may cause error by receiving a self-outputted
DIS.
Selectors 8: CNG detection on/off

If this selector is set to "1," the machine detects a CNG signal according to the condition
preset by selectors 2 and 3 of WSW 18 after a line is connected. If it is set to "0," the
machine detects a CNG signal as long as the line is connected.
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WSW20 (Overseas communications mode setting)
Function
EP* tone prefix
Overseas communications mode
(Reception)
Overseas communications mode
(Transmission)
Min. time length from reception of
CFR to start of transmission of
video signals
Chattering noise elimination at
detection of CNG
CNG detection on/off
EP tone prefix
Brother 8840D Service Manual
MFC-8440/8840D/8840DN, DCP-8040/8045D/8045DN
Setting and Specifications
0: OFF
0: 2100 Hz
0: OFF
No. 4 5
0 0 :
0 1 :
1 0 :
1 1 :
No. 6 7
0 0 :
0 1 :
1 0 :
1 1 :
0: OFF
A-27
SERVICE MANUAL
1: ON
1: 1100 Hz
1: Ignores DIS once.
100 ms
200 ms
300 ms
400 ms
Yes (When CNG goes either
ON or OFF)
Yes
(Only when CNG goes OFF)
No
No
1: ON
* EP: Echo protection
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