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Lasers on RPC Boards Are Started Immediately After Fibers of An IPA Span are Reconnected

Publication Date:  2012-07-25 Views:  42 Downloads:  0
Issue Description
Stations that are at both ends of a long span are configured with RPC detection boards, SC2 auxiliary detection boards, and the IPA function. During fiber maintenance, if the SC2 auxiliary boards detect that optical signals recover, the IPA protection ends immediately and the lasers of RPC boards open no matter when the IPA function is in manual restart mode or automatic restart mode. In most cases, fibers are connected for a short time during fiber maintenance because they need to be spliced for multiple times and may be disconnected again. The immediate end of the IPA protection is dangerous for maintenance engineers if the fibers are disconnected again. For safety, customers want the IPA protection to hold for a moment after fiber reconnection during fiber maintenance.
Alarm Information
N/A
Handling Process

For a span that is equipped with Raman amplifiers, the IPA function, and auxiliary boards SC1 or SC2, to avoid immediate opening of RPC lasers after fiber reconnection, engineers need to disable the IPA function after the lasers are closed, and keep it in the disabled state until the fiber splicing is finished. Using this method, the engineers avoid exposing themselves to high radiation.

Tips: In the case of the IPA function equipped with Raman amplifiers, the RPC detection board can only detect optical power of optical signals that are with frequencies of 192.1 THz, 192.2 THz, 192.3 THz and 192.4 THz. To detect optical power of other optical signals, auxiliary detection boards are required.
Root Cause
Here is how the IPA function works: If SC1 or SC2 boards are set as auxiliary detection boards for a span, the IPA function uses the OSC restart method. When the IPA function uses the OSC restart method, the IPA protection ends immediately after the SC2 or SC1 boards detect recovered signals.
Suggestions

The IPA function can restart in pulse restart mode or OSC restart mode.

When the IPA function is in pulse restart mode, it can restart automatically or be restarted manually.

When both RPC boards and OSC boards report LOS alarms, if the IPA function is in automatic restart mode, the lasers automatically transmit probe light regularly to detect whether the fibers are reconnected; if the IPA function is in manual restart mode, the lasers transmit probe light only after maintenance engineers issue detection commands.

If OSC boards are set as auxiliary detection boards, the IPA function uses the OSC restart mode. That is, after LOS alarms on SC1 or SC2 boards are cleared, the lasers open immediately. If non-OSC boards are set as auxiliary detection boards, the IPA function uses the pulse restart mode. That is, after LOS alarms on either detection boards or auxiliary detection boards are cleared, the lasers open.

END