ADC HDSL4 用户手册

This section provides information about front-panel system alarms, LOS and AIS response, the OCT55 test 
procedure, and loopback testing.

 summarizes all possible system alarms in order of priority as they appear on the front panel. When 

multiple alarms occur, the front-panel display only reports the highest priority alarm. The alarm history screens 
display alarms also, but provide greater detail (see 

). Alarms that are not inhibited will drive the front-panel Status LED to a flashing red alarm state.

PWR FEED 
SHRT

 (b)

Power Feed Short

A short exists between Loop 1 and Loop 2 of 
the HDSL4 pair.

Cannot be inhibited.

PWR FEED 
GND

Power Feed Ground

One of the HDSL4 loops is grounded.

Cannot be inhibited.

PWR FEED 
OPEN

Power Feed Open

A line power open condition exists.

Cannot be inhibited.

SPNn-LOSW

Span(n)-Loss of Sync 
Word

 (c)

The HDSL4 loop has lost synchronization. 
The span closest to the network has highest 
priority.

Cannot be inhibited.

LLOS

Line (Unit) Loss of 
Signal

Loss of the DSX-1 input signal.

Cannot be inhibited.

RLOS

Remote (Unit) Loss of 
Signal

Loss of the H4TU-R DS1 input signal.

Disable the RDA (Remote Disconnect 
Alarm) option. This prevents an LOS 
condition at the DS1 input to a H4TU-R 
from activating pin H. The front-panel 
Status LED still flashes red and the ALRM 
RLOS message displays to alert you of the 
LOS state. LOS is sent towards the 
network from the H4TU-C. This option 
prevents the common occurrences of a 
CPE LOS condition from generating 
recurring alarms and AIS payloads.

LAIS

Line Alarm Indication 
Signal

Indicates an AIS (unframed all ones) pattern 
is being received at the H4TU-C DS1 input 
port.

Cannot be inhibited.

RAIS

Remote Alarm 
Indication Signal

Indicates an AIS (unframed all ones) pattern 
is being received at the H4TU-R DS1 input 
port.

Cannot be inhibited.

LRAI

Line RAI—Remote 
Alarm Indication at the 
H4TU-R (Net signal 
does not have errors.)

Indicates an RAI alarm (yellow) from the CPE 
with an error-free signal from the line unit or 
network. RAI signal is transmitted towards 
the network.

Cannot be inhibited.