
Required equipment
Prior to performing this task, the following equipment must be available:
1. Optical power meter
– Range: –35 ... +20 dBm
– Wavelength: 1310 nm/1550 nm
2. ESD Wrist Strap.
Prerequisites
Prior to performing this task, all used optical ports must be clean. A cleaning procedure
is given in appendix A, section
Background information
LC attenuator
The LC attenuator which will be determined in the procedure described below should
be placed on the INPUT port because this is the furthest physical point on the fiber
line from the OUTPUT port and takes all connector losses into account. If SFPs are
used this proposed solution is important in particular because this causes less level
fluctuations if the fibers are moved.
Fiber plugging / Signal Degrade (SD) clearing
The following can be observed if the fiber is plugged manually:
Firstly, the LOS is cleared. As soon as the bit error rate is low enough (better than ~
10
-4
) the device frames to the signal. As soon as the framing happens, the SD
mechanism starts. The manual plugging is “slow” compared to the reaction time of the
SD detection with fast termination. It takes hundreds (maybe thousands) of frames until
the signal is finally error free. SD will be detected nearly immediately (10 ms).
While the plugging continues the signal gets better. Depending on the speed of
plugging, the SD may get re-detected several times and the interval is restarted.
Finally, SD will not be re-detected anymore (not enough errored frames) and the
interval will expire normally. However, even if the SD threshold is not reached
anymore, most likely the number of errored frames is (due to the hysteresis; see
section “SD detection mechanism”) still too high to clear the SD. Therefore a second
interval of the detection must expire before the SD gets finally cleared.
SD detection mechanism
The SD detection is interval-based. As soon as a SD condition is detected (or
confirmed) or deleted (or confirmed as being non- existent) the detection interval
restarts.
Network establishment and testing
Connecting the fiber cables
.................................................................................................................................................................................................................................
365-374-187
Issue 1, December 2005
Lucent Technologies - Proprietary
See notice on first page
10-5