9800 duty cycle 100%

[JustTakeTheFirstStep]

Users try to access a distant AP without connecting to a nearby AP.
We are looking for the reason.
CleanAir was monitored.
Interferer Type is Continuous TX. I think it's not WiFi.
Duty Cycle is 100%.
It looks like this might be the problem.
What action is required?

[Leo Laohoo]

We have several buildings (the list is growing) where the emergency stairs lighting system uses one channel (about 5 Mhz) in UNII-3.  It is on all the time and this "thing" can blast past over >10 metres past the concrete walls.

We made sure APs near the fire escape do not use UNII-3.  They use UNII-2, UNII-2E.  No DFS detected.

[JustTakeTheFirstStep]

Your answer is very interesting.
Can you provide me with relevant documents?

[Leo Laohoo]

Like this?

[JustTakeTheFirstStep]

Why does the emergency stairs lighting system use radio frequency?

Also, looking at the captured screen shot, the Duty Cycle of UNII-1, UNII-2, and UNII-3 channels is 100%.

[Leo Laohoo]

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@JustTakeTheFirstStep wrote:
Why does the emergency stairs lighting system use radio frequency?

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The emergency stairs lighting is trying to be "green".  If no one is using the stairs the light goes into "half power".  If the sensor detects "movements", the light powers up. The motion sensors use 5.0 Ghz.  

Each light is tuned to a specific channel but starts at Ch 149 and goes all the way to Ch 165.  A well "placed" emergency lighting alternates which channels to use so no two light can "see" each other using the same channel.  

[JPavonM]

The relevant documents are technical ones related to every vendor, and the channel, width and duty cycle is something you may need to ask them to provide, as it doesn't use to be public information.

[Rich R]

We've seen the same with motion sensors for lighting, electric doors and security systems.
Customer installs new system then complains WiFi is broken.  We go to site and find system causing interference.
Customer never makes the connection between new installation and broken WiFi. 
In fact sometimes the people working on the site don't even know about the new installation because it's been done by their head office/facilities management.