Recently we did some repair of some fiber optic cable for the DAS cellular and public safety system at the arena. When it was originally installed, the installer had direct spliced the single mode fiber to the connector jumper rather than use a junction box. I suppose this was to improve the signal, but more likely it was to cut costs.
In any case, a carrier expansion had crushed one of the fiber runs and we had to run new fiber and we put in junction boxes as I am trying to reconfigure the arena fiber to be more modular for future resistance ( no such thing as future proof ).
We were unable to get the DAS head end unit to talk to the remote so I was sure that the new fiber was just mislabeled as it was brand new and showed fine on all testing.
I learned something new. My cabling contractor (Leading Edge Consulting) spoke to someone who operated another site and they mentioned something about an APC end. Indeed, the DAS units use an ‘angled physical contact’ connector or APC. This can be distinguished by a GREEN end on the connectors vs blue. I had never heard of it, but found information on this site.
The connector has an 8 degree offset that reduces reflection and is quite clever, but obviously if you use a normal squared end, the connection will not mate properly. Once we got the proper connecting jumper, it worked perfectly. Imagine that.