ABB EDS500 Series Function Manual page 44

DSL Interfaces
The default value to trigger the pre-alarm Signal quality warn threshold reached is 1 dB
The default value to trigger the alarm Signal quality alarm threshold reached is 0.5 dB
For further alarms see Chapter 2.12, "Alarms and Alarm Configuration".
Command to modify the alarm behaviour
< s e t i n t e r f a c e { d s l 1 | d s l 2 } s q - t h r e s h o l d { { t h r e s h o l d } | n o }
[ a l a r m | w a r n i n g ] >
2.15.6.2 Estimation of Line Length
To estimate an existing (and installed) line's length it is reasonable to investigate the ohmic
resistance. For this a short circuit can be applied at the one end of a 2 wire line (connect line
1 with line 2) and measure the resistance with an Ohm meter at the other end. According
to "Tab. 20: Typical line resistance per km" and the following formula the line length can be
estimated.
Line length: l = R
The resistance measured with the Ohm meter is called R
table is called R
given line diameter.
Diameter [mm]
0.4
0.6
0.8
1.0
Table 20: Typical line resistance per km
2.15.6.3 Estimation of Transmission Rate
In general no definitive predictions can be made about the achievable data rates at a certain
line length as this depends on the signal quality of the DSL signal. However reference values
can be given.
As a reference a family of curves is shown for a copper wire with 0.8 mm wire diameter
(shielded telecommunication cable) with low noise. The horizontal axis shows the distance in
km, the vertical axis shows the signal quality.
44
/ 2R
L T
. The values in the table describe the typical line resistance per kilometre at a
T
Resistance R
Diameter [mm]
137.7
61.2
34.4
22.0
, the comparison value from the
L
[ohms/km] Resistance R
T
minium wire
210.9
93.7
52.7
33.7
Functions
[ohms/km] Alu-
T
1KGT151021 V000 1