WSW20 - Page 287

 App. 

4-24 

Confidential

WSW20 

(Overseas communications mode setting)

Selector 

No. 

Function 

Setting and Specifications 

1 

EP* tone prefix 

0:  OFF  

1:  ON 

2 

Overseas communications 
mode (Reception) 

  0: 2100 

Hz 

1: 1100 

Hz 

3 

Overseas communications 
mode (Transmission) 

  0: OFF 

1: Ignores 

DIS 

once. 

4 

5 

Min. time length from 
reception of CFR to start of 
transmission of video signals 

No. 4  5 
 

0 

0   : 

100 ms 

0 

1   : 

200 ms 

1 

0   : 

300 ms 

1 

1   : 

400 ms 

6 
7 

At CNG detection, elimination 
of chattering noise                       
(Not used) 

No. 6 

7 

0 

0  :  Yes, at both ON/OFF timings 

0 

1  :  Yes, at OFF timing 

 1 

X 

: 

No 

8 

Limitation on CNG detection 

0:  OFF 

1:  ON 

* EP:  Echo protection 

NOTE:

  Selectors 6 and 7 are applicable to models equipped with SDAA circuits. 

z

  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. 

z

  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.)