a few quick questions

Hello folks,

I have run into some interference with another Canopy WISP about 20 miles from me. I am using 3APs at 906,915 and 924. They are using omnis at 910 I think.

My 906 AP is causing interference with his omni.

I can switch the freqs on my aps, just rotate them around. if I did that one time, my 915 would be pointing at theirs. Or I could go completely around to 924.

The freq that you set your AP on needs 4 channels up and 4 channels down for spectrum clearance, correct?

If that is correct, then I am using 902,903,904,905 and 907,908,909,910

That means he is using 906,907,908,909 and 911,912,913,914

To me the only channel that would be completely clear is 924.

So, here are my questions:

Is there any way to set the AP to lower than 906 or higher than 924? It seems like if it could be set to 905 or 904, or 926 or 925 it would give more room…

On the SMs - Do you need to check ONLY the channel you are using and leave the rest blank? My equipment has all three channels that I use checked. Is there any advantage to just setting the one channel?

I have my max range set to 20 miles. If I reduced this to, say, 17 or 15 (or any number), (and they did the same).would that help/eliminate interference problems with theirs? I do not want to reduce my serviceable area…

I know if they would use sectors it would be considerably easier.

Is it possible to set all three APs to the same channel? I know they will overlap some. Would using color codes help with the overlapping?

I just need to know the best course to go.

Thanks everyone.

You need a total of 9MHz of seperation. Thats why Mot specs 906, 915, and 924. You could use really any combination so long as you maintain that 9MHz of seperation.


The only clear channel in their direction looks like 924… You might be able to use 919 if I am reading your post right.


You cannot go below 906, as 906 is the center channel. 4MHz below that is 902, which is the bottom end of the spectrum that we WISPs use. Higher than 924 is 928, and that is the top of the band. It goes liscensed from 928 until the next open portion of the spectrum.

You should be leaving all frequencies selected in the SM’s and then picking the best AP using the color codes. Color codes do not do anything for spectrum management. They simply are provided to assist you in site surveys and allow you to force SM’s to a specific AP.

Placing all AP’s on the same channel will be very bad. Even though they are synced, you still need the channel seperation to prevent the recievers from being mashed on.

This brings us to sync. Sync is great, because it allows you to operate tighter AP’s (physically and RF, all things considered!) and have AP’s that have really sensitive recievers, without making them deaf when they are operating (contention based system).


Example: You have an AP on 906 facing south, and another on 915 facing southwest. CC may be something like 100 on the south, and 101 on the southwest. Your installer in the field is surveying a customer. This customer most likely can hear both, but one is better. He uses AP Eval to look at your AP cluster and sees both, but one is going to be better in terms of RSSI, dB and jitter values. He also sees the color codes of each AP and picks the CC of the best AP and places that in his SM. The SM registers and then he proceeds with the link tests and what not.



If you need to change frequencies in the future, you change them on the AP, and the SM’s registered to that AP will follow suit. You can see how many SM’s have registered on the AP before hand, and match that after changing. Same number is good. Next step is to look at the signal measurements (rssi, db, jitter) and determine if that is working for you. Run link tests to ensure its all good in the hood.



That is my understanding of how it is done. If I am wrong, someone correct me.