User's Manual Part 5

SYSTEM SETUP ROI-S05749
3-16
3.5 Setup Description
The following describes to select suitable functions for the system
operation by the provisioning setup.
3.5.1 Automatic Laser Shutdown Control (OPT INTFC) (SONET)
The OC-3 INTFC (only for OPT) is provided with the Automatic Laser
Shutdown (ALS) function that can be enabled or disabled. If the ALS
function is enabled, the laser output is periodically turned ON and OFF
when the optical cable carrying the OC-3 signal is disconnected
inadvertently, or intentionally during maintenance. When the ALS
function is disabled, the laser output is always ON even if the optical cable
is disconnected. Fig. 3-1 shows a block diagram of the ALS function.
If a fault occurs at point A and the absence of the optical input signal in the
RX 2 lasts for 550 ±50 msec (OC-3 LOS alarm condition), the optical
signal bound for the RX 1 (MUX equipment) from the TX 2 (OPT INTFC
module) is interrupted by a control signal generated inside the OPT INTFC
module. The MUX equipment detects the loss of signal at RX1 and the
ALS function in the MUX will, subsequently, turn off the laser output of
TX1. When the fault at point A is cleared the system can be restored by
controlling the laser output of TX2 through one of the following modes:
• Automatic control
• Manual restart (2 sec.) control
• Manual restart (90 sec.) control
(a) Automatic Control
When 60, 180 or 300 sec.(selectable) have elapsed after the optical
signal entering RX 2 is cut off, the IDU emits laser signal from TX
2 to RX 1 for 2 sec. This would then cause the laser output of TX1
to turn on. If, at this time, the fault at point A has been cleared, the
ALS function will be released and the operation will return to
normal.
(b) Manual Restart (2 sec.) Control
Upon receiving a command signal for manual restart from the LCT
or the PASOLINK network management terminal (PNMT) while
the optical input signal to the RX 2 is off, the IDU emits the laser
signal from the TX 2 to the RX 1 for 2 ±0.25 sec. This would then
cause the laser output of TX1 to turn on. If, at this time, the fault at
point A has been cleared, the ALS function will be released and
the operation will return to normal (if not it returns to automatic
condition).