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I have a wall clock that syncs from WWVB. It was pretty cheap and uses a single AA battery (which seems to last forever). I never have to update the time. Can
by dewyatt 8y ago
I have a wall clock that syncs from WWVB. It was pretty cheap and uses a single AA battery (which seems to last forever). I never have to update the time.
Can satellite time provide an equivalent or better solution here?
- brianwawok 8y agoGPS could yes. Don’t know how many exist but would only add a few dollars in chips.
- owenmarshall 8y agoAnyone who has ever installed a GPS backed NTP appliance in a data center can quickly answer that. For those who haven’t: it involves drilling holes in the roof of your data center for a satellite antenna.
- Hello71 8y agodoesn't the wall work just as well?
- yardie 8y agoGPS requires line of sight to the satellites.
- reificator 8y agoAnd walls have two sides...
- __david__ 8y agoSo all your clocks need to be on outside walls?
- reificator 8y agoNo, but all your satellites would.
- yuubi 8y agoYou can see only about half the sky that way, which means usually getting almost as good a fix as with a roof mount antenna. For best results, you want the satellites to be as far apart as possible in the sky (measured by angle from your position, not miles between them). See https://en.wikipedia.org/wiki/Dilution_of_precision_(navigation) https://en.wikipedia.org/wiki/Dilution_of_precision_(navigat... . If you mainly care about time and can tolerate a few microseconds of error, usually being able to see 4 satellites might well be enough. I remember seeing a gps receiver designed just for time that could maintain sync using only one satellite (it assumed that it was bolted to an immovable object, and it might have needed to see 4 satellites at once at some point).
- myself248 8y agoNo, as I explain here: https://www.reddit.com/r/rfelectronics/comments/6nb6ky/do_cell_phones_receive_gps_signals_from_the_local/ https://www.reddit.com/r/rfelectronics/comments/6nb6ky/do_ce... To get halfway decent holdover performance, you want all the precision you can get when the constellation is good. That requires the best skyview (and least multipath) you can manage.