Yes, we had an LG microwave, took it back after 3 weeks because it knocked out both wifi and Bluetooth. The store didn't want to refund. Said it had to go to warranty repair. Repair shop said they cannot decrease RF emissions, store begrudgingly gave credit.
Ask HN: Does your microwave interfere with Bluetooth? Mine does
161–170 of 182 posts
Re: Ask HN: Does your microwave interfere with Bluetooth? Mine does
#162There's about 1000 watts of RF inside the microwave, it has to be attenuated to less than a few microwatts on the outside to avoid congestion, as they use the same frequency band. I'm amazed WiFi or Bluetooth ever works at all. 8) You can thank Hedy Lamar for that. Try cleaning the mating surfaces around the door thoroughly. If that doesn't work, consider replacing the microwave or relocating the speaker.
Wifi has an "interference robustness" option which is designed with microwave ovens in mind. The power output of a microwave is a sine wave, because it's powered from your AC line power, and doesn't emit energy during the zero crossings. "Interference robustness" times packet sends (and lengths) to be when the microwave is producing the least amount of power. Thus, you spend half of every 60th of a second irradiating…
There is also a fun regulatory hack in bluetooth.
As it is frequency hopping, FCC considers it spread spectrum, but only if it hops across a large enough set of channels.
This matters because spread spectrum radios can run significantly more power.
Bluetooths frequency hopping system avoids interference to it and from it by dropping channels with interfernce or other users from the hop set.
So with enough interference, even monentary interference and the hop set reduces and regulatory limits require dropping power from 100-200mW to 25mW. This usually cuts the connection.
Re: Ask HN: Does your microwave interfere with Bluetooth? Mine does
#163Earlier quoted context omitted.
I know of at least two Panasonic inverter microwaves that failed within a 5 year period of ownership. Mine emitted white smoke warming up some tea while I was in another room. I hope to God it wasn’t beryllium. I still have a Panasonic OTR microwave, but it’s inverterless. It appears to be an improved design of a GE model from the same OEM.
We have a Panasonic Inverter microwave here, must be 20 years old. It works great and I have never noticed any interference with WiFi or Bluetooth, both of which also get a lot of use in the kitchen. Just another anecdata point!
The earlier inverter models sound like they’re workhorses. The problematic ones I knew of were from around 2012 - 2014.
Re: Ask HN: Does your microwave interfere with Bluetooth? Mine does
#164Earlier quoted context omitted.
I know of at least two Panasonic inverter microwaves that failed within a 5 year period of ownership. Mine emitted white smoke warming up some tea while I was in another room. I hope to God it wasn’t beryllium. I still have a Panasonic OTR microwave, but it’s inverterless. It appears to be an improved design of a GE model from the same OEM.
Probably burnt paint from the inside of the waveguide. Happens frequently when the mica sheet that covers the injection port gets moisture from steam (who'd have thought - steam in a microwave?!?) Simple fix is to replace the mica (a few cents from AliExpress) and use steel wool to get rid of any carbon residue around the injection port.
It sounded like there was no magnetron load on the power supply, because the cooling fan was spinning a little faster and the interior was a little brighter. This was during the few seconds between the smoke show and from me pulling the plug.
There was indeed a char mark on the mica sheet, but the beryllium terror at the time was enough for me to chuck it.
Re: Ask HN: Does your microwave interfere with Bluetooth? Mine does
#165Earlier quoted context omitted.
And on the follow-up, "Why use 2.4(5) GHz for microwaves?" Because it happens to be a convenient frequency that water absorbs readily, which is the easiest way of heating up what we'd want to heat with a microwave (read: food). https://en.wikipedia.org/wiki/Electromagnetic_absorption_by_... And once we'd polluted the frequency for any stable commercial use, why not use this weird carve-out for a little thing called W…
To further build off your rabbit hole, this is also why 2.4ghz long range wifi connections (like via a yagi antenna) is also problematic. Foliage fucks with your range. Also why central air conditioners and wet walls create wifi shadows.
But the rabbit hole goes further. Higher frequencies are more susceptible to wall in the middle problems, you can see that easily with 5GHz WiFi, lower frequencies might be better but require larger antennas and might suffer from other limitations. As everything else in engineering this is a compromise.
Re: Ask HN: Does your microwave interfere with Bluetooth? Mine does
#166Earlier quoted context omitted.
Good lord, who uses that much power in a microwave? 600W are enough. (Clearly, the idiots microwaving fish in them. In one office I know they put a sticker with a crossed-through fish symbol after one particularly pungent incident)
> Good lord, who uses that much power in a microwave? 600W are enough. And next thing you'll say is that 1000W is enough for a kettle? 110V 15A AC is enough for an outlet? Here in Europe, we don't have the patience for slow-boil kettles and slow-boil microwaves :). (FWIW, I always stick to the full 1000W available on my microwave, and sorely miss the 1250W that my dad brought from Sweden when I was a kid.)
I'm German. High-powered microwaves IME only make for highly unevenly warmed food.
Re: Ask HN: Does your microwave interfere with Bluetooth? Mine does
#167Earlier quoted context omitted.
That's because the equipment installed in the galley is going to be tested for operation with the specific aircraft. Meanwhile phone radios (not WiFi, not Bluetooth) used to have interference issues with various aviation systems (with some 5G bands still causing issues). Additionally, outside of interference issues from phone systems (and various other non-ISM band radios), the order helps preventing people from doin…
The restriction on cellular phone use on a plane comes from the FCC not FAA. As far as the FAA is concerned as long as you can demonstrate (through standard tests) that a class of aircraft is tolerant of electronic devices (which the manufacturers can do), it’s up to the airline if they want to allow it. They’ve even greatly simplified the process due to the explosion of different electronic devices over the last cou…
It's a bit of both. Aviation cares not just about specific plane, but also interaction with other systems - which in this case in USA are in purview of FCC.
That said, both reasons are involved, though usually mobile networks tend to optimize for signal in horizontal plane in a way that makes them reduce receiving capability from outside of it.
Re: Ask HN: Does your microwave interfere with Bluetooth? Mine does
#168Bluetooth and WiFi both borrow their spectrum from microwave ovens. It's typical and expected that microwave ovens will cause some interference with other users of the 2.4GHz ISM band that are very nearby. Microwaves operate at very high power levels and are required to be shielded for human safety, but the permissible leakage power is relatively high compared to typical WiFi and Bluetooth devices---there's a simple…
Could I make a legal bluetooth jammer that is actually a small microwave oven then?
Probably not legally.
Re: Ask HN: Does your microwave interfere with Bluetooth? Mine does
#169Sounds like. A microwave problem
Re: Ask HN: Does your microwave interfere with Bluetooth? Mine does
#170Bluetooth and WiFi both borrow their spectrum from microwave ovens. It's typical and expected that microwave ovens will cause some interference with other users of the 2.4GHz ISM band that are very nearby. Microwaves operate at very high power levels and are required to be shielded for human safety, but the permissible leakage power is relatively high compared to typical WiFi and Bluetooth devices---there's a simple…
And on the follow-up, "Why use 2.4(5) GHz for microwaves?" Because it happens to be a convenient frequency that water absorbs readily, which is the easiest way of heating up what we'd want to heat with a microwave (read: food). https://en.wikipedia.org/wiki/Electromagnetic_absorption_by_... And once we'd polluted the frequency for any stable commercial use, why not use this weird carve-out for a little thing called W…
IIRC, the precise frequency was further narrowed to _not_ be absorbed as well by water, because then all the energy would hit the surface of your food and not the inside (although I'm still not sure if that is relevant at a wavelength that is almost as large as the food you'd want to heat).
And then, again IIRC, finally pinned down slightly to the side of that because of the parts that could be sourced to build the first ovens.