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All SM's stuck running lowest modulation

Contributor

All SM's stuck running lowest modulation

Not a nice thing to start a monday with.  I do have a ticket going through the hoops right now too, but in the mean time thought I'd ask if this has been seen before.  I *thought* I heard of it happening in the 14.x firmware, and I am currently running 15.1.1 on this particular AP.  Can't be noise, very remote site, nearest tower (and it is ours) is 20km away.  SM's operate correctly when they connect to adjacent sector (at least, the ones that can) and this site was running fine for at least 4 months now.  Rebooted ap, rebooted some of the SM's.  

 

Typical operation on this AP 8x and 6x with a couple that dipped to 4x at worst.

 

red all the way down.png

 

 

 

5 REPLIES
Moderator

Re: All SM's stuck running lowest modulation

Is this 900 MHz 450?

 

 

Have you opened a support ticket?  

 

That screenshot doesn't make a lot of sense to me.

Contributor

Re: All SM's stuck running lowest modulation

Ticket is open, this is a 3.65 AP.  No response there yet.  Thought I'd ask here if someone saw this before.

 

About an hour after posting this thread I logged back in and everything is back to normal.  Radios are humming along in 64qam and 256qam as if nothing happened.  It wasn't cosmetic either, we had enough complaints coming in to get us looking in the first place.

 

All morning yesterday this AP ran like crap, and then suddenly it's back to normal without having touched it.  I slammed in 15.1.3 last night, will be keeping an eye on it.  Bad jumpers or moisture in connectors maybe?

Cambium Employee

Re: All SM's stuck running lowest modulation

Steven, I'm not aware of any issue like this currently. What release were you on before?

Did your receive powers go down when you were having the issue?

Good idea about moisture in the cables, but I'm not a hardware expert (450 software guy stuck in a cube), but I wouldn't expect it to affect both paths at the exact same time? If one path just bad, then it would be 1X-4X MIMO-A. But all is at 1X MIMO-A. Hmmm.

 

Did you have any LBT (Listen Before Talk) events? I see beacons still at 100%, so that's a good sign and probably means no on LBT events. 

If it happens again on 15.1.3 please connect capture of the AP and a few SMs and send it in.

Regular Contributor

Re: All SM's stuck running lowest modulation

Yeah - Been there, seen that, climbed the tower (water in one of the pigtails PMP450) replaced all while we were there.

 

As you can see, you've lost (at least looks like) one side of the AP (H) and the second doesn't look very good.  Why the units continue to show they have good receive power is beyond me (obviously a problem).  You'll also notice there's no SNR (NA H) and the power levels will be frozen.  They really should either reset to NA like SNR or display actual receive levels.

 

Have you climbed yet?  This will bite you in the rear again when you least want it to.  Be proactive.

I'm telling you I had the exact same indications.  

 

Contributor

Re: All SM's stuck running lowest modulation

At time of issue we were running 15.1.1 and have been since November.

 

We've closed our ticket with Cambium, it's been running fine for a couple days now.  We'll see what field crew finds whenever they go out.