ERRCS Antenna Monitoring Systems – Not Ready For Prime Time
The mandates in certain jurisdictions for Antenna Monitoring Systems (distribution side) is dreamy at best. It is easy for the NFPA and associated AHJ’s to conceptualize code changes, however without the technology piece in place, this section of the code is a false start.
As a concept, AMS is a novel idea. Monitoring the distribution antennas of an ERRCS DAS system can be of value, but at what cost. And is it necessary? The passive elements (cable, couplers. & antennas) rarely fail once installed and tested. I think these efforts are misplaced. If one antenna is damaged or fails, the other antennas in the network can assist in uplink and downlink. If an entire branch is down because a cable has been severed or damaged, the system will pick up the VSWR, and trigger an alarm. What the AHJ’s should be focused on is the enforcement of annual inspections, which will pick up any passive failures at the time of inspection.
There are only a few OEM’s that have solutions available and they really are not ready for prime time, and expensive. Some require a maximum of 20db in path loss in the passive infrastructure, including coupler values, to work with RFID polling. This may work for smaller venues but is virtually impossible in larger venues. Other’s require smart couplers with a monitoring gateway in the head end. Each coupler reports changes in VSWR (Voltage Standing Wave Ratio) and can trigger an alarm if there is an open short in the network. These couplers can be 4-6 times more expensive than standard couplers which add tremendous costs to the build. Furthermore, VSWR reflections back to the BDA will already trigger an alarm, so this type of system may be redundant.
I applaud the efforts of the local AHJ’s, to make these systems survivable, but when the technology side cannot effectively deliver solutions to comply with the code, it creates an impasse. These initiatives need to be researched as to efficacy before instituting in the code.
Digitechx Wireless Inc.
Will Washburn, is the CEO of Combined Operations for Digitechx Wireless Inc., a national provider of ERRCS and iDAS solutions.