[time-nuts] Next step up from basic GPS/PPS timekeeping
Bob Camp
kb8tq at n1k.org
Wed Feb 24 19:34:17 EST 2016
Hi
WWVB DSO’s were a pretty common thing back in the 70’s and 80’s. You could hold
fractions of a ppm with them. With manual intervention / scheduling you could get into
the “couple ppb” range on a good week.
Comparative numbers would be 1x10^-11 on a GPSDO. All the same qualifiers about
“is that really this or that” apply equally (or more so) to it’s WWVB cousin.
Bob
> On Feb 24, 2016, at 5:22 PM, Hal Murray <hmurray at megapathdsl.net> wrote:
>
>
>> From what others on the list have said before, WWVB offers performance
>> that's at least a couple orders of magnitude worse than GPS, even if you
>> correct for all of the expected diurnal variations in LF propagation. Given
>> that a fairly pedestrian GPS module offers a nominal PPS accuracy of ~10ns
>> for $25...
>
> Yes. But it would be fun to measure the diurnal variations.
>
> I thought WWVB was actually good at that. It's ground wave rather than
> bouncing off the ionosphere. But I'd like to measure both WWVB and WWV.
>
> Has anybody built a WWV(B)DSO? You would need a stable oscillator so you
> could average over days or weeks rather than hours. I'm thinking of a
> surplus rubidium. Maybe a manual screwdriver adjustment would be good enough
> and a PIC/AVR to make a PPS and fake GPRMC.
>
>
>
> --
> These are my opinions. I hate spam.
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
More information about the time-nuts
mailing list