[ntp:questions] Re: WWVB 60kHz Receiver

Richard B. Gilbert rgilbert88 at comcast.net
Sat Apr 15 13:33:49 UTC 2006

Ry wrote:

> Speaking of WWVB clocks: does any company actually manufacture a
> preconfigured WWVB clock with a serial interface anymore? I've been
> unable to find one. Spectracom and the other manufacturers that used to
> make them seem to have switched over to GPS entirely.

WWVB Receivers are occasionally available on e-Bay for $100 - $300.

> I'm 1462.5 km (4.8 ms) from the WWVB transmitters, which is well inside
> the coverage area maps on the NIST site. I figure WWVB is my best
> (only?) option for a refclock at this location. Is sub-milisecond
> accuracy possible using a WWVB refclock? 

Possible?  Yes.  Probable?  No!  If you want to invest about $35 in an 
"atomic clock" You can hang it on your wall and check the reception 
indication several times during the work day.  If you get solid 
reception during daylight hours a WWVB receiver just might give you 
sub-millisecond accuracy.  If you lose signal during daylight hours, 
forget it!

> The NIST site says 0.1 to 15
> ms phase error, which is two orders of magnitude. I see ~5 ms average
> offsets when I sync with nearby stratum-1 servers via NTP. Would WWVB
> perform any better?
> I'd rather not build a WWVB receiver and antenna if I can just buy one
> for use with NTP.

I never had a WWVB receiver to try it with.  If someone wants to lend me 
some equipment I'll compare it with my GPS refclock.

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