ePMP On-board GPS Sync Loss

We have been dealing with a sync loss issue across many of our ePMP APs.  The problem is occuring on many APs throughout the network.  These towers are geographically spread out over 60+ miles.  I cannot find any commonalities that would point me to a specific cause.  It just seems like the GPS pucks lose tracking all of the sudden.  Sometimes all satellites will stopped being tracked, sometimes it just wont have enough for sync. Sometimes sync will be lost for seconds, other times minutes or hours.  Sometimes when it is sunny and clear, sometimes when it is cloudy.  We have not noticed this issue on any of the 450's with on-board GPS.

Once we started graphing the SNR of all tracked satellites we noticed that a satellite will go from tracked with a high SNR to not even visible.  Very few satellites are tracked for any length of time.  Attached is a screenshot of one such graph.  The graph is a 12-hour period of the SNR's of all tracked satellites.

Thanks in advance for any input.

Hello Charles,

Would you be willing to try our current BETA load 3.3-RC14? Some customers with very similar GPS issues are reporting positive results (http://community.cambiumnetworks.com/t5/ePMP-Beta/ePMP-Beta-Release-3-3-RC14-now-available/td-p/69247/page/3).


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Hey Charles, if you dont mind what system are you using to generate those graphs?

What AP (1000 or 2000) and what type of GPS puck (old round vs new octagon-ish shape)?

See: http://community.cambiumnetworks.com/t5/ePMP-2000-and-1000/ePMP-1000-GPS-lite-AP-just-lost-all-GPS/m-p/68532#U68532

I may see about loading the beta software onto one set of APs as a test.

The graph was generated using Zabbix.

This issue has occurred on both 1000 and 2000 radios. I do not have enough 2000s deployed to determine if the problem rate is about the same.  In general, the 2000s track more satellites.

I believe all the GPS pucks are of the round variety.