Interfaces and Terminals as of I7.8
28
System Interfaces
sy
d-
023
9/2.
4
– I7.
8
– 0
7
.2009
2. 1. 4. 2
Attenuation on analogue network interfaces
With analogue network connections you have a choice of four different attenua-
tion settings:
•
Long
or.
•
Long D
for long lines
•
Short
or
•
Short D
for short lines
On lines with a loop resistance < 280
Ω
,
Short
or
Short D
should be selected to
avoid problems with echo or instability (feedback).
The settings”
... D
" settings are used to increase the volume in an "analogue ex-
change - digital terminal" connection type by 3 dB in both directions as this type of
connection is generally perceived as too quiet. The reference level is modified ac-
cordingly on the expansion card. Due to the restriction to the aforementioned con-
nection type, the setting “
… D
” does not result in an increase if an analogue user-
network interface is involved in a connection.
Note:
The setting”
... D
" setting should not be used (or only once the stability
conditions have been thoroughly clarified) if the equipment (Terminal
Adapter) operated on digital interfaces also features a four-wire to two-
wire conversion, i. e. an analogue two-wire interface.
Initialization setting
Analogue network interfaces are set on
Long D
.