101–110 of 180 posts
Those kinds of projects are super fun, and the writing here is good, so congrats to the author. That said, why do people need clocks? I usually know the time, day or night, within 30 minutes or so, and if I need to know the exact time (which happens rarely if ever), I look at my watch. There are zero clocks in my home. I would find it quite aggressive to have a big display that tells me exactly what time it is. Come…
> The end result exactly matched my expectations—the best criterion for success that I can think of. With an LLM providing the heavy code lifting and the CAD work, I think I spent more time waiting on supplies to arrive than on anything else—something attributable to my lack of planning and the ease of next-day delivery.
I think the author robbed themselves of a deeper understanding.
[1] https://www.npl.co.uk/products-services/time-frequency/msf-r...
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>Typically a receiver should be able to get time within seconds from cold start if there's enough sky visibility, and once it does it is as accurate as it gets regardless of position fix status. It'll be good to far better than seconds when it first gets a signal and will get more accurate (microseconds to nanoseconds) once it has a position fix because it can then compensate for the delays in the signal propagation…
What I meant was that it will take seconds to get an accurate time from the sky (as accurate as it gets without specialistic techniques or equipment to consume it, and better than NTP already).
You can still get pretty accurate time (microseconds) with the GPS almanac which is broadcast over ~15 minutes and only updated every few months.
Doing really fast time acquisition isn't a hard problem but it's a hardware problem, you can't really change how an ordinary GPS receiver operates, you have to have a custom receiver.
>damned if I could find one with a red seven-segment display that I liked (maybe someone else’s search kung-fu is better than mine?). The secret to finding an inexpensive radio-controlled clock/alarm/watch of your liking it to be German. They LOVE their Funk-Uhren! Sadly they typically only support Germany's DCF77 signal. You can also trivially find DCF77 receivers as components to use in a project.
There's a map here: https://www.ptb.de/cms/en/ptb/fachabteilungen/abt4/fb-44/ag-...
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I did went GPS+ntp route. I have a few raspberry pis on my lan that serve NTP time. (you need more than one) Over the years I've experimented with various flavors. Right now I have a mix: 1) a pi3 with a gps hat and a battery backup for the pi itself. It uses ntp 127.127.20.20 for gps time, and 127.127.20.28 for PPS. The SMA antenna goes to receiver at the window 2) a pi3 with USB gps on a cable going to the window 3…
> I've also kind of wondered if GPS might be able to give you a time less accurately but quicker. Sometimes I look at the NMEA GPS output, and it sometimes doesn't have a position fix, but it does give out a time + week number No. Accurate time is one of the prerequisites for acquiring a position fix, and it's the one that's the easiest and fastest to obtain from the sky. Typically a receiver should be able to get ti…
Which is a thing we shouldn't be requiring here. Picking up a single satellite without any position data is enough to drive a clock.
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I meant the clock itself doesn’t need an internet or local network connection, with which it could do things other than syncing the time.
Then I think this is a trap to get some kind of proprietary app onto your phone. The clock could set itself from radio signals: standards-compliant. The clock could have WiFi or Ethernet and use [S]NTP: standards-compliant. The clock could have a SIM and use NITZ: standards-compliant. But BT it is. So now rather than having a dependency on standard or generic resources, it requires a BT pairing with the right kind of…
This was my thinking as well, and why I rejected the idea. I'm not installing some rando company's information-harvesting data-selling garbage app on my phone to do something that the clock should do itself.
Could it not just be an iPhone on its side at this point?!
I’ve had a Phillips “atomic” alarm clock beside my bed for 23 years that just sets based on radio signal and auto restores if the power is lost, to which it has a backup 9v battery. There’s a time zone setting offset slider and a DST slider. I basically touch it twice a year, maybe another if I move time zones. I’ve only had to touch it for DST (never switched time zones). Takes me conservatively 10 seconds to find a…