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

#1

Post by Jeff_Brown » Thu, Oct 05, 2023, 12:47 PM UTC

I can see the Faraday cage in my microwave. It's never cooked anything outside of it. But if I put my phone on one side of it and a Bluetooth speaker on the other, running it interrupts the connection to the speaker. Sound gets through but it's choppy.

Seems bad, right?

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

#2

Post by kevinherron » Thu, Oct 05, 2023, 1:22 PM UTC

Not great, not terrible.

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

#3

Post by mikewarot » Thu, Oct 05, 2023, 1:26 PM UTC

There'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.

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

#4

Post by baal80spam » Thu, Oct 05, 2023, 1:44 PM UTC

Yes, sound in my headphones is distorted when I go near a working microwave oven.

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

#5

Post by counterpartyrsk » Thu, Oct 05, 2023, 1:46 PM UTC

Does the sound quality improve if either the phone or speaker are inside the microwave? We must test all possible scenarios.

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

#6

Post by AuthorizedCust » Thu, Oct 05, 2023, 1:46 PM UTC

Microwaves are well known to interfere with 2.4 GHz communications. That’s one of Bluetooth’s channels.

https://en.m.wikipedia.org/wiki/2.4_GHz_radio_use

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

#7

Post by [deleted] » Thu, Oct 05, 2023, 1:48 PM UTC

[deleted]

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

#8

Post by causi » Thu, Oct 05, 2023, 1:49 PM UTC

Depends on both the microwave and the bluetooth device in question. My favorite pair of headphones are rather inexpensive and my microwave is a couple decades old and very high-wattage, and I get interference if I stand within a couple feet of it. I haven't had any other microwave or any other bluetooth device experience noticeable interference.

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

#9

Post by zh3 » Thu, Oct 05, 2023, 1:50 PM UTC

Microwaves typically run 2.500GHz, most bluetooth and wifi is from 2.400 to 2.480GHz to keep some space between them (so if you want to minimise WiFi/Microwave issues on 2.4Ghz, use a low WiFi channel).

Bluetooth is adaptive and will hop frequencies to find quiet space in the range above, however microwaves are an intermittent source so when they go on the leakage will kill any bluetooth that's on a nearby frequency.

An easy way to see this is with a BBC microbit; you can measure the signal strength on channels 1 to 100 (2.4 to 2.5GHz in 1MHz steps) and so plot the local RF sources (WiFi, Bluetooth, Microwave, etc.).

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

#10

Post by zzless » Thu, Oct 05, 2023, 1:54 PM UTC

counterpartyrsk wrote: post #5

Does the sound quality improve if either the phone or speaker are inside the microwave? We must test all possible scenarios.

I understand this is a (good) attempt at humor but this might be an interesting idea to see if Bluetooth leaks from inside the microwave oven (or from the outside in). Of course, the microwave has to stay off, naturally :)