ePMP 5GHz GPS AP sector back-to-back. eDetect showing each AP as an interferer


We have an ePMP 1000 5GHz GPS AP sector using the ePMP 1000 5GHz antenna setup.  The north and south sectors are set to the same frequency, 20MHz channel (non-DFS).  When I ran eDetect, eDetect is saying / showing that the other sector (back sector) is an interferer to each other.  So the eDetect has this as RED.   It then shows the ePMP clients.  It lists the Interferer's SSID as the back-to-back sector / opposite side.

We do have the GPS Frequency Reuse settings set to Front Sector (North AP) and Back Sector (South AP).  The sectors are at about the same vertical height.  There is horizontal separation of at least 15ft - 25ft or so.

Any ideas on how to get this GPS synchronization and frequency reuse working properly or to allow these APs not to be interfering with each other.


What signal is eDetect showing each sector at? There's probably nothing to worry about, and it's normal if you see the opposing sector in eDetect. Everything else you mention indicates that you've properly configured GPS sync and back to back frequency reuse.

eDetect will show any radio that's sending out WiFi beacons on the same channel and channel width.


Hi Eric;

OK.  The eDetect on the South AP is showing [-69 (Red) and -82 (orange)] <--- Interferer's  and [-66dBM as the Detecting Device Info].

The reason for concern and/or what prompted us to check the eDetect was that the North AP just didn't have clients registered on it anymore. Rebooted the SMs. nothing would connect. Rebooted AP. Nothing would connect.  This sector worked fine for some time.  Only had about 3 SMs registered on it. 

To eliminate the possibility of a bad RF radio, ran the eDetect and other tools.  Changed the frequency about 2 points/selections up and down from the frequency we originally had it on.  One SM re-registered.  The other SM which was important to us did not reconnect.  That SM can faintly see the East sector AP.  But it won't connect to that AP.

The SM of interest to us is a Force 180.

My concern for the AP side was why it is now showing my own APs in GPS mode as a 'bad' interferer.  Have to work on the SM later and see why it won't connect.  It just dropped out of the sky.



eDetect uses a tiny portion of Tx part of the frame to listen to interferers. Therefore, if your APs are properly sync'd, one AP's eDetect will hear the back AP because the back AP is still TXing. You can safely ignore eDetect picking up the back AP. 

That said, are you using the Cambium sector antennas? If so, you should be fine as they have sufficient FB ratio for back-2-back frequency reuse. Also, a Spectrum Analysis on both APs simultaneously to check for any external interference may help troubleshoot registration issues on the North AP. 



Hi Sriram;

OK.  Understand those points.   Yes, we the antennas are all Cambium antennas.  What is the difference between doing the eDetect (at the AP side) and selecting AP only and AP/Sms options?  


Hi Lincs_Chel, 

If you select AP only, eDetect scans for and displays only the interferers seen by the AP. If you run AP and SMs, eDetect will display interferers seen by the AP as well as interferers seen by the SMs registered to it. 


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OK.  So the eDetect Ap/SM feature can basically be used to get a quick assessment of what the 'air' looks like in that sector.  And then we could possibly know (quickly) if we should be looking to use another frequency channel?

Does it do it summary from all the SMs or does it list each registered SM and their interferers?

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It lists all registered SMs and thier interferers. A couple of things you have to remember regarding eDetect:

1. It provides a list of 802.11 interferers

2. It provides interferer currently on the channel. It cannot detect interferers partially or fully off channel.