[time-nuts] Homebrew WWVB TX simulator?

Bob Clements time&nut* at clements.org
Sun Sep 19 00:13:31 UTC 2010


> The NIST web page is here:
>   http://www.nist.gov/physlab/div847/grp40/wwvb.cfm
[and the iers page and the historic leap second list, in a
subsequent message.]
> I assume you can find the fine print there, but they probably aren't easily
> machine readable.

Yes, sure, I know about those resources.  You're right, they're
meant for eyeballs, not code.  I remember seeing the IERS
bulletin taped to the wall at WWVH the first time I visited, back
in the late 80s or maybe early 90s.

Back then, someone had to drive out to the site on the UTC day before
a leap second (typically new year's eve) and flip a toggle switch
to insert the :60.  And then (harder, given parties and hangovers)
the next day to prevent another from happening the next UTC midnight
(2PM Hawaiian time).

I did a bit more digging on the NIST site, and it appears that
you can get the Leap info, DST-pending info and DUT1 (current but
not pending) info via ACTS, the modem dialup service.  But none
of the internet services include those.

There is a site name "acts.nist.gov" in the DNS, but nothing
responds on any of the usual ports.  So maybe they intend
to work on this issue.

> The NTP package includes a utility to generate the audio for WWV.
> It's util/tg2.c in any recent NTP source package.

Yup.  Only tg.c in the production release, but tg2.c is in the
development tarball -- hadn't seen the improved version.

It looks like it does a good job on the IRIG and IEEE stuff.
But the WWV / WWVH is kinda minimal.  It says it is intended
to test the detector code, but doesn't include the 500, 600 and
440 Hz tones, which it ought to for a proper test.  Also, no
double ticks for the DUT1, and no voice announcements.

My own tcg code does all that, and adjusts for WWV vs WWVH
tone schedule and tick frequency.  (Not ready to release to
the world, though.  I should think about that.)  This was
written back when the RFP went out for the current generators
to replace the Audichron drum announcers and add the new code
stuff.  I built a prototype, then decided it was nuts to
submit an actual proposal.

Tnx again & 73,
Bob, K1BC

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