[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