Comment by jacquesm
10 hours ago
For GHz signals water is a pretty good dampening material, I can tell on some links whether it is foggy!
10 hours ago
For GHz signals water is a pretty good dampening material, I can tell on some links whether it is foggy!
Your microwave uses 2.4 GHz specifically because it's particularly well absorbed by water :)
A friend told me once that his mouse stops working when someone is using the microwave. His room was on the backside of the kitchen.
When I took a look at it, it turned out that his (proprietary) wireless USB adapter for the mouse was very close to the band of the noise of the microwave. The microwave was also not properly grounded and shared a circuit breaker with his room, as apparently the kitchen was formerly larger and then split into two rooms by the landlord.
That was quite funny seeing that problem happen in action, he was always joking about a ghost in the machine, and I was joking about him being radiated by his microwave.
The cool part is years later in University one of my commilitones told me that his mouse stops working when the fridge turns on. The first thing that I checked was whether or not there's noise on the power circuit, et voila, easily fixed.
Noise on powerlines is annoying, very frequently present and sometimes dangerous.
Long ago there was this case of a factory that pressed desks out of steel sheets. Their main press (an absolute monster) had taken someone's arm off and they couldn't find the cause. It turned out that near the roof there was an air conditioning unit that that had a flaky relay in it that drew a gigantic spark on disconnecting, enough to upset the latch that controlled the safety interlock on the press, causing the press to move by itself.
It took quite a while to find it.
> A friend told me once that his mouse stops working when someone is using the microwave. His room was on the backside of the kitchen.
I had to disable a 2.4ghz access point a couple years ago because a bathroom had a passive IR detector for the light switch that would never let the light shutoff. Because detecting IR is a pretty weak signal, I guess these switches amplify it. The issue is the circuit also acts as a weak antenna for 2.4ghz and thinks its seeing IR when it's actually just amplifying and seeing the 2.4ghz beacon signal.
RF gets weird. Something I've thought about over the years is how my FM radios at my old house would sometimes pick up aviation radio which should be AM well above a tuned FM frequency. Apparently this is due to the common design being a superheterodyne receiver which comes with a few quirks (such as causing some small interference itself when it's receiving).
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This happened in my life too!
I had a Customer complaining about bad WiFi in a conference room. Every time I checked it I had good performance. Eventually I attended the meeting most of the of the complaints related to just to observe.
What I observed was workers from cubes near the conference room microwaving food for their lunch in the break room right across from the conference room.
That's a common myth. There is no special water resonance at 2.4GHz, it's just a frequency allocated for general use. Early microwave ovens didn't use 2.4GHz