Self Interference...possibly?

Hi all just trying to assess if I am experiencing self interference on my tower locations. The towers are a rural setting, not to much for noise and I am using 4 epmp 3000 with cambium 90 degree sectors using gps synch/front/back frequency reuse. I have 2 ptp 550 with 34db 3ft antennas(altelix) on the tower, one slave receiving from a different tower at 23km away and a master sending out to next tower.
My 4 epmp antennas are 3ft apart in ABAB setup. My ptp 550s with antennas are roughly 4ft below my sector antennas…is that enough height distance between then or do they need more… The altelix are not high performance antennas.

In a setup like this I typically like to keep the 5GHz PtP’s physically/vertically separated as far possible from the 5GHz PtMP. I’d also make sure that they’re using bands far away from each other… like 5.7 for PtP and 5.1 for PtMP. I’d use 50/50 ratios for the PtP’s and try for frequency reuse. I’d use 75/25 ratios for the PtMP radios and again, try for frequency reuse and tight guard bands between adjacent sectors. That being said, after many years of being a WISP, I no longer typically use multiple, high performance 5GHz PtP’s to feed a site. The 5GHz band is more valuable for PtMP use then PtP use, especially for larger sites with multiple operators. Now, I just plan and budget to use licensed links at pretty much every site. Using licensed links makes things so much easier on many levels.


@Eric_Ozrelic I really appreciate your response and info… as per your response, other than licensed ptp links, that is exactly how I have it setup for my ptmp and ptp. Now I do have room to lower my ptp 550s to create more space so I think I will plan for that. Now in regards to getting 550s into frequency reuse, what are the pieces of that puzzle, component wise? Also, to utilize frequency reuse for my ptp links, do you need the ptps that are co-located to both be masters?

PTP550 needs to get sync via ethernet port… so I’d suggest getting a Packetflux RackInjector.

I believe that they both need to be masters, but I’m not 100%… i.e. I’m 100% sure that GPS sync will work with all the masters collocated on the tower. I think that using 50/50 ratio, you can have masters at different sites, but I’m not 100% on that.

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Be sure that A and B radios on the same channel can not hear each other
or Sync will not work correctly

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How/where does one check that they cannot hear each other? In my case they are ptp 550 radios

The altelix dishes are a high performance dish, dont discount them. I have several and they out perform the radio waves 3ft dish I have.

Generally if you can touch two antennas then they are too close to each other. We use a 1m from the tower rule for any back to back antenna sets and do not have issues.

Keep your reuse pattern in mind and make sure you maintain it.
Your backhauls should be in another part of the band as Eric stated, they should be gps timed as well and be at least 2m vertically separatedand 1m stood off the tower. Yes I know that this increases tortional wind loading but that can be compensated forbwith additional tortion stabilizers.

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