Ok this one i've not seen before, SM can't see AP

We have a 450m that is having some coverage issues (due to vertical range, it's pointing at a hill and cant cover bottom of hill and people on top.

We decided to install a new 450i with a 30x30 cone antenna to cover the people bunched at the top.

Normally this would work without issue, find clean channel, assign color code, install and move customers with poor signal over to the new panel.

So far we've tried, 2 Accesspoints, 2 sets of nmale cables, the cone antenna, a sector antenna, different clean channel and nothing helps. The AP Eval on the SM side never sees the new AP, all channels are enabled, even tried only the new and current channel being enabled still it only sees the existing connection to the 450m in apeval.

I even set the 450m color code as secondary and the new color code as primary thinking maybe it was a display issue, but nope it popped back on to the secondary cc on the 450m.

Set the SM to do a spectrum scan on bootup, and it has a nice high -50 peak where the new access point is, changed channel and the peak moved with it...

But just can't get the SM to see it, and yes i've checked by 2-3 different client radios in the area and all they see is the 450m they are connected to.

Any ideas?

PS. Forgot to say: All loaded with 15.1.5

Hi Csup,

Have you tried with the 450i AP frequency both above and below the 450m frequency ? (i.e. is the sweep through frequencies always seeing and locking on to 450m first)

Are both on 2.5ms frames (if 450i was on 5ms frame it is 'harder' to see)

Finally if you can get easy physical access to SM and remove the 450m colour code (or frequency) but leave the 450i does it now see it ?

If that doesn't give us some clues we'll have to wait for advice from Chicago team.

best regards,


We're going to go for a drive with a 450b in the car with a battery pack and see if we can connect/see the 450i ap without having a secondary color code, but i don't think its going to help

One of the SMs i was testing with i had turned the 450m to a secondary color code, and the new unit as a primary and it connected to the 450m and was waiting to rescan for a primary node.

So i take that to mean the SM couldn't find the primary color code and failed over to secondary.

Note : for an AP to be “evaluated”, the authentication / encryption settings on the SM must match the AP (not the secret values, just the algorithm selection etc).
It might also be an idea to enable Installation Color Code at both ends until the link is up and stable

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So we went for a drive with a pmp450b in the coverage area were able to connect without issue.

However once again doing a scan apeval on 8 radios connected to the 450m in the same area don’t show the AP as even existing in the apeval

Thought maybe some weird interference changed to 3 highly different channels 5605 5705 5835 and still the apeval never shows the 450i AP after a clear statistics and rescan

Tried it on several customers 450 and 450b units remotely.

Then got annoyed and changed a colleagues 450 in the area to only the 450i channel and only the 450i color code and he never connected to it, had to go to his house and reconfigure it back to the 450m channel and color code and tada it popped online, meanwhile right next to his radio the test 450b we brought was online doing speed tests.

Really don’t understand how non of the SMs that are connected to the 450m can see or conn ct to the new 450i, but a brand new 450b out of box with our security settings set connects and surfs fine on it


Did you try connecting the new 450b to the 450m as well ?

If you collect engineering.cgi from an old &new 450b then we can compare those.

Also collect them from the 450m and 450i and we can compare those (although this is slightly more difficult)

files can be sent to me


best regards,


I'm betting you already have this enabled, but just want to make sure you have enabled the "SM Display of AP Evaluation Data" on your AP.

Also are all your AP's GPS Synchronized? What are you using for you synchronization source? APs use this synchronization to exactly center their frequency (like 5800.000 MHz) and then SMs store this. It's possible that one of your AP's isn't exactly right on the center of the frequency (like 5800.100 MHz).

What channel bandwidth are you using? The larger the channel bandwidth the easier it is to "find" so the more it is allowed to drift. Maybe could set your 450i to 40 MHz (even though channel isn't clean) just for a test?

Andrew and Bart from cambium have been helping me via email. Today we finally narrowed it down and got it working the issue was we had the 450m on generating sync and the other apps all on cmm4 gps.

It appears their may be an issue where if the generating sync is too far off timed from the synced ap units the sm just doesn’t even see them.

So the SMs connected to the 450m couldn’t see any other aps during an apeval even after several reboots.

And an AP connected to a 450i could connect or see the 450m at all even though they were visible in spectrum scan.

We ended up running a ugps to sync the cmm4 and the 450m, which kicked everyone off the 450m due to the drastic shift in timing I guess. Then after a while they all eventually came back online. And apeval showed a dozen available aps including the new 450i.

Lesson learned… generating sync can cause phantom access points.

Andrew said he opened an internal jira ticket to track the issue as normally the sm scam should randomize the oscillator so that it picks up non synchronized aps but is instead apparently getting stuck on the timing of whatever AP it was last associated to for a decent while and rebooting wasnt flushing it.


Hi CSup,

Charlie was the one who was about to get a bunch of diags in his email just before the 'fix' came in. Should have done that earlier I guess, would have saved alot of head scratching.

It seems like a scenario that could happen quite easily as new APs are brought in that may or may not have the GPS source sorted or not.

I'll be in touch with Charlie to see where we go with this.

Thanks CSup.

best regards,


Well I was out on PTO celebrating my independence from the Brits… :slight_smile: