Frequency Hold Off

ePMP such as 200, 3000 sometime goes frequency hold off. whats the issue anybody???HELP!!!

There can be several reasons for that. For example, if you’re using a DFS channel, and if it detects nearby RADAR, the rules are to jump to a secondary channel and to go through a ‘Hold Off’ period, where it 'listens to see if the new channel is clear before it starts transmitting. So that’s normal (expected) behavior in the face of a DFS event.

There are other reasons too – for example, if you’ve selected an AP to be GPS Synced to do Frequency Reuse across your Sectors, when you first boot up the AP it will do a ‘Hold Off’ period on it’s initial power up, so that it can establish GPS lock and get it’s timing synced up with your other AP’s. Again, in this situation, a ‘hold off’ could be an expected (intentional) behavior.

On the other hand, if you have an AP which is set to use GPS and if it loses GPS sync for some reason… then the AP only keep transmitting for a certain amount of time before it goes into ‘hold off’ and it waits for GPS lock to re-establish. If that’s what’s happening, there should be a Red GPS Icon on the AP’s main interface… and the ‘MONITOR → GPS’ screen should indicate GPS Sync issues. That can be caused by a few reasons… we had an AP doing that because it was our ‘North’ facing sector, which means it was on the north side of that tower, and so there was the tower structure and the other three sectors were blocking the GPS signals to the west, south, and east. So - we had to move the GPS puck antenna a bit so that it had a clear view of the southern sky. Of course, if you’re losing GPS sync, your reasons could be different… I’m just saying that loss of GPS sync could be one possible reason for ‘hold off’ to happen spontaneously.


Thankyou for your information… but we use gps unsync radio devices.

Yes, those were just some examples. You didn’t supply much in the way of details, so I was just guessing and giving some examples of times when ‘Hold Off’ is expected.

You should probably include some screen shots showing the issue when it happens – make sure to indicate what Firmware Number you’re using, etc,
etc and I’m sure some of the forum members will help you track down the issue.

We will need to know which frequencies you are using and which country you have your equipment set to. Also use the monitor>system log page to see why your AP is going into hold off.

Bijay - Hold Off can also be shown on an SM as part of it’s scanning & registration process. I was using a Force200 @ 2.4ghz today, and noticed it says ‘Hold Off’ as part of that process… until it’s totally registered and ready to use. So in that context, ‘Hold Off’ is expected.

However, if you’re getting it at random or unexpected time – please attach screen shots with as much details of what you’re seeing as you can, and we’ll see what we can do to help out. :slight_smile:

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This frequency hold off issue can see on ePMP 2000,How to fix?. Pls support & Help.

Hi Thanzaw - post some details of what you are seeing, and post some screen shots. There are lots of times that ‘Hold Off’ is a perfectly normal behavior, depending on how things are set.

So post several screen shots of your config, and describe the situation, and the community can try to help you out


Ok - well, a thing I see is GPS Sync Down.

If the AP loses GPS lock, it’ll count down the time limit you have set, and it’ll then shut down the transmitter. So, if this is what’s happening, you may just need to figure out what’s caused the gps issue.

Is this ePMP2000 outdoors, or just testing inside? Does it have it’s GPS antenna connected with a clear view to the satellites? Or, maybe you need to reconfigure the Sync so it’s not using GPS, if that’s appropriate for your needs?

Also, make sure you are using the latest Firmware - there have been GPS firmware bugs which have been fixed from time to time, so you’ll want to be sure to use a firmware with all the appropriate GPS fixes.


to add to Ninedd, your external gps antenna (do not rely on the internal one!) needs to be the thin flat antenna or the new thick round ones. If your antenna is an original (more than 4 years old by now) then replace it. Also, depending on where you are, you need to point the antenna in the correct direction and orientation. Closer you are to the equator the more flat the antenna can lay, but if your near the Canadian border (use this as a latitude reference only, if your south of the equator, just invert the latitude) you will see an large improvement by tilting the antenna vertically with the cable pointing down. The direction you point the antenna depends on several factors, for the northern hemisphere, point southerly but if you have a cell tower in that general direction, point it so the cell tower is off to the side. There are a lot of gps satellites up there and you only need 4 for these to work so pointing east or west away from a cell tower will not hurt you.


Thanks ninedd,Outdoor Sector is placed on the roof of the building, the height is about 65 meters.
I will test is new firmware .

OK - yes, the root cause of the ‘Hold Off’ in your case, would be because you have your Synchronization Source set to GPS, and yet the GPS can’t find/lock on the satellites. That could potentially be an issue with your GPS antenna location, it might be an older firmware issue, or it might just simply be ‘one of those things’ and the just AP needs a power cycle. BUT, whatever the reason, the GPS seems to be the culprit.

Another solution (of sorts) is to reconfigure the Synchronization Source to be ‘Internal (No Sync)’ and to save/reboot, and that should get the AP broadcasting again. Of course, after that change, it won’t be Sync’d any longer, so it might then interfere with your other nearby AP’s. But - that change would get it broadcasting again.


Thanks a lot ninedd:

As long as its not an ek3L, look at a packetflux cambium sync injector and a syncbox jr. This is cmm5 timing and just works!

still a few hours ago from in Hardware Version
5 GHz Force 400 CSM Radio (ROW) frequency hod off issue please help me

It appears that that SM isn’t linked to any AP yet.

It’s normal for an SM which is not connected to an access point, to obviously not know certain things, such as what its frequency will be, what it’s channel width will be, and also for it to be not transmitting yet… it gets info like that (and more) from the AP once it’s linked to it.