User manual

Chapter 3. What is Auto Configuration
3-1
Some of the embedded functions do not have a separate command to setup
but some of them are auto sense with some configurations and change itself
configuration. Some of them are always enable function.
I. Wetting Current
Wetting current, also known as loop sealing current, is a low-level DC current
applied to a loop for the specific purpose of maintaining cable splice integrity by
preventing the build-up of oxidation. The “enable” applies a relative –42 ± 2 V DC
voltage to the cables and allows 2~3 mA of current to flow at all times. As with all
STU-C type devices, they have the ability to source wetting current. The SHDTU03
will automatically enable wetting current as STU-C type. As STU-R type, it always
terminates the wetting current.
II. AIS (Alarm Indication Signal)
Alarm Indication Signal (RAI) is an always enabled signal transmitted
automatically to the connected device when the remote E1 line drops or the SHDSL
line drops. For example: When STU-R E1 RX line is dropped, STU-R will send the
status to STU-C via EOC or command. STU-C will send AIS (Alarm Indication
Signal) to DTE.
DTEDTE
STU-C
STU-R
E1 SHDSL E1
E1 Line Drop
RAI
EOC or CommandAIS