Brother 8250P - FAX B/W Laser Printer Service Manual page 126

Selector
No.
1 EP* tone prefix
Overseas communications mode
2
(Reception)
Overseas communications mode
3
(Transmission)
Min. time length from reception of
4
CFR to start of transmission of
5 video signals
Chattering elimination for CNG
6
detection
7
8 CNG detection on/off
Selector 1: EP tone prefix
l
Setting this selector to "1" makes the equipment 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 equipment 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
l
These selectors should be used if the facsimile equipment malfunctions in overseas
communications. According to the communications error state, select the signal specifications.
Setting selector 2 to "1" allows the equipment 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 equipment to ignore a DIS signal sent from the called station
once in sending operation.
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.
l Selectors 8: CNG detection on/off
If this selector is set to "1," the equipment detects a CNG signal according to the condition preset
by selectors 2 and 3 of WSW18 after a line is connected. If it is set to "0," the equipment detects
a CNG signal as long as the line is connected.
WSW20
(Overseas communications mode setting)
Function
This operation suppresses echoes since the first DIS signal
V - 33
Setting and Specifications
0: OFF
0: 2100 Hz
0: OFF
No. 4 5
0 0 : 100 ms
0 1 : 200 ms
1 0 : 300 ms
1 1 : 400 ms
No. 6 7
0 0 : A (During CNG ON and OFF)
0 1 : B (During CNG OFF only)
1 X : C (No elimination)
0: OFF
1: ON
1: 1100 Hz
1: Ignores DIS once.
1: ON
* EP: Echo protection