4
X
E1/G.703 P
LESIOCHRONOUS
M
ULTIPLEXER
O
PERATING
M
ANUAL
IOA77-1F
9
May 2007
Table 4.
Detected failure conditions and accompanying actions.
Actions taken
LED diode
Rela
y
1)
E1 channel signal
G.742
frame
bit
Failed
element
Failure
condition
Alarm
LOOS
LOF
10
-3
10
-6
LDF
RAL
LOES
UA
NUA
AIS
Loss of signal
UA
;
C O
AIS signals are
transmitted to all E1
interfaces
;
Loss of frame
synchronization
UA
;
C O
AIS signals are
transmitted to all E1
interfaces
;
Error rate
> 10
-3
UA
;
O C
AIS signals are
transmitted to all E1
interfaces
;
Error rate
> 10
-6
NUA
;
C O
---
Transmitter
failure
UA
;
---
Linear optical
interface
Remote alarm
;
---
Local
interface
E1
G.703,
G.704
Loss of signal
UA
;
C O
AIS signal is transmitted
via E1 channel to
multiplexer
Entire device
Loss of power
supply
UA
C C
;
– LED diode is on
1)
– alarm relay, an activated alarm is indicated by closed relay contacts (C – closed contacts,
O – open contacts). TM-77.1 version is not equipped with alarm relays.
3.2 Additional
channels
A frame is generated in the multiplexing system. The frame includes two bits, which
are used to generate two additional synchronous bidirectional data transmission channels
at the speed of 10 kbit/s each.
The first of the bits – Alarm Indication Signal Bit - is used to transmit an alarm signal
to a remote device.
The other bit - National Bit - is used for communication between the supervision systems of
a local and remote device.
