[time-nuts] NIST

Dana Whitlow k8yumdoober at gmail.com
Mon Aug 13 07:24:56 EDT 2018


Note to all;

Be cautious about getting time of day from consumer GPS products.  All that
I have encountered
(so far) exhibit T.O.D. errors up to a few tenths of a second, and the
error is not repeatable from
session to session.  Some do have PPS outputs, which are typically claimed
to provide usec
level of accuracy, but most do not.

I routinely use WWV to verify correct setting of my WWVB-synced watch and
kitchen clock.  I have
 occasionally seen severe setting errors, which I attribute to attempts at
syncing in the face of poor
WWVB reception conditions.

My impression is that none of the time codes currently in use by broadcast
NIST time signals
contain forward error correction or even error detection features.  If this
is wrong, please somebody
correct me!

BTW, there are a fair number of Heathkit clocks in the wild which use WWV
(as opposed to WWVB)
for syncing.  An old college-era housemate with whom I keep in touch owns
and still uses at least
one of them.

Dana


On Mon, Aug 13, 2018 at 5:25 AM, Mark Spencer <mark at alignedsolutions.com>
wrote:

> I'm trying hard to think of routine users of WWV / WWVH other than amateur
> radio operators, time nuts, and the occasional academic / scientific study
> that uses the transmitters as a signal source.
>
> Perhaps some boaters still use the time signals to set their chronometers,
> but WWV /WWVH probably wouldn't be my first choice for that application if
> I had access to GPS.
>
> Perhaps some other users of the radio Spectrum occasionally use the
> signals as a basic test signal ?
>
> I use the time signals for my amateur radio hobby when I already have an
> HF receiver and don't want to mess with using GPS as a time source.  I only
> need accuracy within perhaps a third of a second so manually setting a
> computer clock while listening to WWV works for me.
>
> For my own interest I'd be curious in knowing of other routine uses of the
> WWV / WWVH time signals.
>
>
> Mark S
> VE7AFZ
>
> mark at alignedsolutions.com
> 604 762 4099
>
> > On Aug 12, 2018, at 2:08 AM, Bob kb8tq <kb8tq at n1k.org> wrote:
> >
> > Hi
> >
> > One would *guess* that stopping WWVB (and killing mom and pop’s “atomic
> clocks”) would not be a reasonable thing to do.
> > It gets a lot of voters mad. I doubt that very many voters (percentage
> wise) would notice WWV and WWVH going away ….
> >
> > Bob
> >
> >> On Aug 11, 2018, at 9:00 PM, jimlux <jimlux at earthlink.net> wrote:
> >>
> >> On 8/10/18 12:45 PM, Robert LaJeunesse wrote:
> >>> I'd say it does get more detailed, with the $49M in cuts described
> generally in groups here:
> >>> https://www.nist.gov/director/fy-2019-presidential-budget-
> request-summary/fundamental-measurement-quantum-science-and
> >>> One item: "-$6.3 million supporting fundamental measurement
> dissemination, including the shutdown of NIST radio stations in Colorado
> and Hawaii"
> >>
> >> I wonder if that's WWVB, or WWV & WWVH
> >>
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