It is important to have measured optical powers in the firmware (readout by software) for the following reasons:
- they can't easily be measured everywhere (e.g. with multi-fiber breakout cables, and behavior of transceivers)
- measuring with meters is currently a time-consuming manual process which one wants to avoid at 2am
- manual measurement means plugging/unplugging fibers in often dense-fiber conditions (e.g. at a patch panel) which can create further problems
- our fiber installation is become more complex with LCLS2 (more fibers, more delicate single-mode, longer runs, more patch panels)
- would allow for early detection of marginal signals
- would potentially allow for automated checks in future
Philip Hart offers the following suggested approaches:
- Obtain and disseminate more complete test kits (this would address the measuring MTP problem)
- we keep spare octopus etc. cables on hand for swapping out the various fiber segments
- we keep tested transceivers on hand
- we intend? would like? to qualify all transceivers when receiving cameras
- maybe we need a regular program to replace or retest old transceivers
- sometimes we have dry compressed air on hand to clean interfaces
- write down the various debugging steps somewhere easily locatable
- I forget where we wrote down our previous flowchart, Kaz
- It would be great if we planned for dying fibers and had system redundancy allowing one to hot reconfigure different lanes
- of course we would want to have tested spares strung for this
- having by-hand-only-swappable tested fiber bundles might be resource intense at the patch level etc. but I think it would be worthwhile in many cases
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