I'm surprised and impressed that this works. I would've guessed phones have enough RF shielding and low-pass filters in the audio path to prevent this.

“One of the higher-frequency harmonics inevitably created by any real-world DAC during playback will then be the original fundamental, which should leak to the environment as a short-range radio transmission via the ad-hoc antenna formed by the physical wires and circuit traces in the audio output path.”

Sometimes I think I’m a smart guy…and then I read of people doing shit like this.

I once programmed my TI-84 calculator to do exactly this! The only missing thing was a circuit to convert the audio jack output voltage into the needed form for an antenna. I had the CS know-how but no EE know-how, so I never got it to work. It was fun to dream about confusing my high school's clocks though. (Sadly, the other obstacle was that the clocks only listened for the signal overnight, which improved their chances of detecting the weak broadcast out of far-away Colorado.)

You can apparently lock shopping trolleys using the same kind of principle - https://www.tmplab.org/2008/06/18/consumer-b-gone/

And https://www.youtube.com/watch?v=LmSyb0kBvGE

I was like is the clock transmission only 50khz and then wow it relies on harmonics.

I have a big old analog radio-controlled clock in my classroom, and it's always about 4 minutes fast, which would drive me nuts except most of my students can't read analog time so they're never confused by it.

Regardless, I'm excited to try this out next time I'm in the classroom. I'm a little confused by time zones, however. My clock has no controls on the back whatsoever (at least that I can find, I haven't opened it up), so I assume it doesn't know what time zone I'm in.

So do I need to set the time zone on the station emulator? There's an "offset" setting, but it says it's only for correcting "minor errors."

I remember years ago I bought a clock that advertised it set itself using the atomic clock broadcast.

Which it did. The very first time it was plugged in, and then never again after. The clock also kept horrible time, it lost a couple minutes every month. Truly an astonishing piece of wtf engineering.

It says it doesn't work on iOS Safari, but iOS users can get the "Clock Wave" app from the app store which does the same thing. (And allows fun time zone tricks with clocks from other countries.)

I’ll have to see if this can work with a multi band 6 gshock, I assume it’s similar to a standard atomic clock?

Shame there's no video demonstrating it working. It's a fun idea but without a demo, I'm left wondering about the efficacy.

And the 2024 lateral thinking award goes to...

This is pretty darn cool, but I have to say I was somewhat let down by the WWVB signal. I was expecting the entire audible range instead of simply the extracted data. That being said, that's also really darn cool.

I find the WWV/WWVB droning soothing somehow.

I can't tell if I'm fooling myself or if this actually (partially) worked. Is it possible for only the hour and seconds to sync if the signal isn't perfectly received? How long is it supposed to take to sync the time? Is it possible that this can confuse clocks that get a strong enough real signal while the phone is running this nearby?

I just tried it on a clock that has only ever successfully synced once many years ago, and it's still in the same bad location that never seemed to get a strong enough signal.

Its crappy little LCD animation did indeed seem to dance in sync with when I would turn the signal on and off on my phone. It took a few minutes of trying but then suddenly the hour and seconds updated to the exact time. Had to set the minutes manually :/

What? Wow

I read the title as 'Train Station Emulator'. :)

This certainly looks impressive but it’s a bit misleading to say it works on “almost any phone” when it doesn’t work on iPhone (which only allows mobile Safari)

Whenever I see things like this, my first thought is that somebody is going to write something to mess up nearby atomic clocks, just because they can, then I think- why, why did you do this?

Then someone will respond: you’re just catatrophising- anyone could’ve done this years before now, and I’ll say no, because it wasn’t up on frontpage HN there with code so that anyone would think of it. Then they’ll say, well why did you tell everyone that idea then! It’s your fault! Then I’ll say that someone would’ve done it if it weren’t me. Then I’ll go have a beer.