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Ask HN: Does your microwave interfere with Bluetooth? Mine does

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Re: Ask HN: Does your microwave interfere with Bluetooth? Mine does

#73

Yes. I've wondered about this for a while. Because although the microwave is supposed to be fully shielded, when I take EMF readings on it with my TriField TF2 EMF meter, it's spitting out >100mW/m^2 when it's turned on. And I've seen this happen with just about every microwave I've tried this on. The only ones that haven't seem to be those expensive integrated under-counter ones where the tray slides out rather than…

"Microwaves are supposed to be perfectly shielded" is one of those myths that just won't die. Microwaves are allowed to leak a lot, with exactly "how much" dependent on whatever agency writes the rules where you live of course =)

In the US, for instance, it's the Center for Devices and Radiological Health (CDRH), part of the FDA, that sets the rules for microwaves, with the performance standard set forth by CDRH allowing leakage (measured at five centimeters from the oven surface) of 1 mW/cm² at the time of manufacture, and a maximum level of 5 mW/cm² during the lifetime of the oven.[1]

A strong wifi router or bluetooth transmitter may be transmitting at one or two orders of magnitude greater than the microwave's allowed to leak, but if you're closer to the microwave than the wifi/bluetooth transmitter, or the microwave is simply between you and the wifi/blueooth transmitter, or especially if you have a low power transmitter, that microwave's going to wreak havoc.

[1] https://transition.fcc.gov/Bureaus/Engineering_Technology/Do...

Re: Ask HN: Does your microwave interfere with Bluetooth? Mine does

#74
Bluetooth 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 reason why. From a legal perspective, Bluetooth is essentially pretending to be a microwave oven and making use of the permitted leakage power.

This is the cost of the historical regulatory situation that most of these unlicensed radio services use the ISM bands originally allocated for microwave heating. One of the advantages of newer WiFI standards, particularly WiFi 6E, is that they finally change this situation by using the U-NII bands allocated specifically for unlicensed short-range digital communications, rather than for microwave heating.

Mind that this is all in the context of US spectrum regulations, although other countries have largely harmonized their approach. I have a lengthier treatment of the topic here: https://computer.rip/2022-04-14-unlicensed-radio.html

Re: Ask HN: Does your microwave interfere with Bluetooth? Mine does

#75
post #42

Earlier quoted context omitted.

I like headphones primarily on devices that go in my pocket because they move with me. When I use headphones at a non-portable device I'm likely to damage them by walking away with them on. I use a BT headset at my PC for this reason; I can get up and pace &c. without worrying. Quick tip if you are using wired headphones while doing chores: run the cable under your shirt; that should leave little-to-no exposed cable…

I am also a get-up-and-pacer, and agree with your reasoning completely.

I pace, too .. but not if I'm using a desktop - only when on the phone (and occasionally) with a laptop

Re: Ask HN: Does your microwave interfere with Bluetooth? Mine does

#76

My neighbors have something crazy emanating from their house. None of my Bluetooth devices, from Bose to Plantronic to new AirPods Pro, survive signal connectivity when I walk past their house. The connection gets very disrupted and the devices have trouble reconnecting. So I have to leave everything off when I go for a run and not connect headphones until I make it to the end of the street. It’s weird.

could be a continuously recording wireless camera that likes to hog spectrum

Re: Ask HN: Does your microwave interfere with Bluetooth? Mine does

#77

My neighbors have something crazy emanating from their house. None of my Bluetooth devices, from Bose to Plantronic to new AirPods Pro, survive signal connectivity when I walk past their house. The connection gets very disrupted and the devices have trouble reconnecting. So I have to leave everything off when I go for a run and not connect headphones until I make it to the end of the street. It’s weird.

Sometimes it’s things like baby monitors or low-cost cameras blasting analogue video.

Re: Ask HN: Does your microwave interfere with Bluetooth? Mine does

#78
post #12

My data is anecdotal, but I've observed that Panasonic inverter ovens that I've used interfered in the 2.4GHz range, while models of other brands (e.g. GE) have not. (This is unfortunate because Panasonic seems to be the only brand that can actually adjust power output, whereas the others simulate lower power levels by cycling on and off.)

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.

Re: Ask HN: Does your microwave interfere with Bluetooth? Mine does

#79

Bluetooth 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…

The international allocation of 2.4GHz spectrum for microwaves happened at lobbying of USA, but is global - and exists in order for airplane galleys to be equipped with microwave heaters and be allowed to travel internationally.

Re: Ask HN: Does your microwave interfere with Bluetooth? Mine does

#80
There's a particular spot on a local highway that interrupts my wireless CarPlay connection if I spend too long in it (eg when traffic is slow). It's right next to an exit with a bunch of buildings (including a hospital) so I'm sure there is some massive emitter in one of those buildings. I'm still at a loss about what could cause that kind of interference inside a major city and still be legal.
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