[time-nuts] WWV receivers?
albertson.chris at gmail.com
Wed Oct 26 13:05:17 EDT 2016
I started to set up a WWV based reference clock. As for a receiver SDR is
the best way to go but I built a tunnel front end. It is easy to do
because it needs to only work at ne specify frequency so you can use a
crystal filter with norrow bandwidth. The SDR receiver did direct
conversion that sampled in quadrature using a stereo sound card type
interface. I disagree that even the cheap sound cards are good enough.
Get one that does 24-bit sample because they have enough dynamic range so
they can still work without a human operator tuning a gain knob.
The part I did not do was to modify the NTP reference clock drivers to
accept audio feed from Jack Audio. This would allow internal software to
route audio between applications and not have to use multiple sound cards
and analog cables which seems silly.
Other projects came up and I figure it the world ends and the Internet goes
dark and GPS fails I can still know what time it is by watching the sun set
over the ocean every day.
Actually I've disconnected the GPS from my NTP server and notice only a 5
millisecond error on average using just pool servers
On Wed, Oct 26, 2016 at 5:46 AM, Nick Sayer via time-nuts <
time-nuts at febo.com> wrote:
> If you’re in North America, a CHU receiver is a lot easier to make than
> WWV/WWVH. The CHU timecode is just BEL 103 AFSK at 300 baud - it was a
> one-chip solution 20 years ago when I made one in college. On the software
> side, you’ll want a serial line discipline kernel module of some sort that
> timestamps the incoming characters. The result is as good as HF radio will
> get you, which is to say probably 2 or 3 orders of magnitude minimum worse
> than GPS.
> IMHO the diversity of which you speak is exactly what NTP delivers. I
> believe NIST and USNO run NTP servers that aren’t sourced from GPS. Folks
> with Cesium clocks could conceivably do the same to provide independent
> > On Oct 25, 2016, at 11:54 PM, Hal Murray <hmurray at megapathdsl.net>
> > tshoppa at gmail.com said:
> >> I'm all for a diversity of systems - putting all our eggs in the GPS
> >> seems unwise (and I maintain WWV receivers hooked to NTP at home!)
> > What is available in the way of WWV receivers? Anybody got a summary
> > --
> > 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/
> > and follow the instructions there.
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> and follow the instructions there.
Redondo Beach, California
More information about the time-nuts