It's an old building with bad bad walls. Big 30x20ft open rooms with center corridors. One interior wall + 20 feet from AP gives -70 dB for example.
There are microwaves. 2.4ghz phones are possible as well. Blue tooth devices such as writing tablets. We are surrounded by neighbours with their home 802.11g. The spectrum analyzer shows a messy mess.
The building has three floors and three wings off the main building. It's a thin coverage installation... so many users don't have a choice but to connect to the 11g radios.
The site tech knows all this of course; it's a terrible environment for 11g. And I normally would not feel the need for further investigation. There is a specific user area where the reports are repeated; and even though they have been given denser coverage to compensate the reports persist.
But it's really those signals going up and down that have me curious. Since I had never noticed that before I was wondering if there is a problem.
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During my test which produced the attachment I had the spectrum analyser going as well. The building was empty except for janitorial staff and myself.
Although I did not see anything in the spectrum analysis that looked like a microwave or 2.4ghz phone (and I'd never be able to pick out blue tooth in that mess), still the signal yoyoing is consistent to every 5 seconds... I found the number of blips is 12 blips per minute with regular interval in the test that produced the attachement.
With the thin coverage and bad walls, those signal blips drops to below -85dB for those users I would normally consider in range.
... I hope it's not just normal dead air when the AP doesn't have anything to say... :)
