Brother DCP-7030 Service Manual page 264

<WSW20>
Selector No.
1 EP* tone prefix
Overseas communications
2
mode (Reception)
Overseas communications
3
mode (Transmission)
Min. time length from reception
4
of CFR to start of transmission
5
of video signals
6
At CNG detection, elimination of
chattering noise (Not used.)
7
8 Limitation on CNG detection
Note:
Selectors 6 and 7 are applicable to models equipped with SDAA circuits.
• Selector 1: EP tone prefix
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 useful when the machine fails to transmit at the V.29 modem speed
and always has to fall back to 4800 bps transmission.
The setting made by this selector takes effect only when the Overseas Mode is set to ON.
• 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.
The setting made by selector 3 takes effect only when the Overseas Communications
Mode is set to ON. (The setting made by selector 2 is always effective.)
Function
No. 4 5
No. 6 7
App. 1-25
Setting and Specifications
0: OFF 1: ON
0: 2100 Hz 1: 1100 Hz
0: OFF 1: Ignores DIS once.
0 0: 100 ms
0 1: 200 ms
1 0: 300 ms
1 1: 400 ms
0 0: Yes, at both ON/OFF timings
0 1: Yes, at OFF timing
1 0: No
1 1: No
0: OFF 1: ON
* EP: Echo protection
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