Those numbers on cable...

On a recent troubleshooting event, we found that the cables from the public safety and another service provider's antennas were crossed. This created some interesting problems. 


Once we suspected the crossed cable (thanks to Kevin Wysocki), tracing the cables from the roof-top antennas to the head-end equipment became the main challenge - in this particular case, cables from roof-top antennas to lightning protector were all LMR 400, and then from the lightning protector to the equipment were all 1/2" RFS cable. The fact that most of these cables are hidden above the ceiling tiles didn't help either. This is when the numbers printed on the cable comes handy.

Single Point of Failure

I recently (inadvertantly) rebooted a DAS in a courthouse by leaning on the wall. Talk about Hall of Shame...

I was troubleshooting the public safety part of an existing multi-carrier DAS, sitting on the floor, hooked up to the DAS head-end.  After a while got tired, and leaned back on the wall. There was a single plug going into the wall outlet which was connected to 2 UPS units, the whole head-end was connected to these 2 UPS units - basically, this DAS had a single point of failure. While I leaned back, I guess, I wiggled the plug and the power connection went out. Although UPS took over, but the latency in the UPS made the DAS reboot (this reboot shoud not have happened, but it did!). 

Besides the fact that I may be few fries short of a happy meal, I learned a few things:

1. Do NOT to use a plug with its stem sticking out. Touching the stem (especially accidentally) may cause problem.