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It's one of the easiest radio signals to pick up, a cardboard box with a few turns of wire around it and single transistor are enough in most of Europe.
It's not well known, but quite a few LW transmissions also carry timecode. TDF Allouis in France and Radio 4 in the UK (R4 is pretty cool because it also carries certain 'additional data'). A couple of source that went off air relatively recently were HBG75[ and Loran .
I guess the proper term is "chip", as in DSSS CDMA.
Today even the most basic microcontroller could easily adjust the UTC time to the user's timezone. If this was built today people would laugh at the idea of broadcasting anything else that UTC.
I even used to have a wrist watch which was able to synchronize with it.
What i can't recall tho is if it really worked to set the date/time on my computer :)
I personally couldn't get my decoder working with new Linux though, the lack of sysfs GPIO broke the only decoder I could find.
I think it kinda indicates how DCF77's popularity has dwindled.
Last but not least : I should mention that this researcher J.M. Friedt has an amazing amount of wonderful material about clocks, oscillators, SDR and so on... http://jmfriedt.free.fr
And more specifically on DCF77, I could find http://jmfriedt.free.fr/dcf77.pdf and http://jmfriedt.free.fr/dcf77.mp4 (among other things)
Which doesn't necessarily mean one of them is used for setting the actual clock display.
Imagine my surprise, sitting in my old, beat up Opel Corsa after installing a high-end Kenwood radio which, shortly after turning it on, automagically set the time right.
At first i was like "what the... is going on" and after digging in a little bit, i never understood why other manufacturers and OEMs won't do the same - they rather have you manually change the clock twice a year.
That’s solvable by “jump one hour forward” and “jump one hour backwards” buttons, though.
If they want to sell the same car worldwide, it would be a bigger problem.
But why do you think that it'd show the wrong time?
In my mind, if left as is, it'd show the wrong time, no?
What's the first thing you check after you get up from your chair after your flight has landed at its destination? I know i'm looking a) at my smartphone b) for the (local) time and if it has c) changed automatically yet.
Imagine you're making an appointment with a local restaurant and have to do calculations for the right time first, because your smartphone shows the time for your hometown?
If you limit it to terrorist attacks, the twin towers had been operating for decades.
Which is obviously not the case of a freaking radio antenna.
Using it to sync my citizen watch in Australia.