[time-nuts] NIST

Peter Laws plaws0 at gmail.com
Mon Aug 13 09:52:44 EDT 2018


On Mon, Aug 13, 2018 at 8:10 AM, Bob kb8tq <kb8tq at n1k.org> wrote:
> Hi
>
> Ok, this is Time Nuts. We probably have a pretty good sample of those who use this and that as a source of time.
> We also are reasonably conscious about what we are doing. NIST’s claimed reason for running WWV (and WWVH) is to
> distribute accurate time and frequency.


> No, I”m not debating how badly we need third or eight tier backups. The question is purely - what is it actually used for?


I've never posted here and am mindful of the S/N ratio message sent
out this morning but I am glad to see a post like this.

I would be very sad if I could not tune to 10,000,000.000 000 Hz
(usually, but the others occasionally, too, though I haven't copied
the new/old 25-MHz beacon yet) and hear the reassuring beat of WWV.
Given all the garbage on most of the radio bands, amateur or
professional, especially MW, WWV's programming is about the best out
there.

But I don't use them for time.  Everything at work is NTP with three
Symmetricom (yep, just old enough) S100s disciplining a set of servers
that users aim at.  Occasionally, someone fusses about "needing" PTP
for something or other "because it's better" until we start mentioning
the cost of the hardware and they suddenly decide that NTP is more
than enough.  Yes, NTP relies on GPS (and I guess the other GNSSs
these days) for the most part but there are other sources of time out
there that are not GPS based.  Dave Mills, W3HCF, included hooks for
WWV receivers in the NTP reference implementation on which most NTP
clients are based, but in all the years I've tinkered with NTP, I
don't ever remember seeing a Stratum 1 advertising that it's
disciplined by WWV.

Some buildings where I work have Primex master clock systems - GPS
receiver -> 72-MHz transmitter -> battery-powered wall clocks.  Some
clocks don't get a good signal but that's more a function of who
positioned the master clock (not me!) than a fault with the system
itself.

WWV/WWVH/WWVB never enters into the picture anywhere on campus AFAIK.

As for voters suddenly marching on their Congressmen's office because
their WWVB-disciplined clock no longer keeps time let me ask this: if
WWVB stopped transmitting how many people who have "atomic clocks"
would 1) notice 2) understand that the atomic clock is actually
elsewhere, and 3) that the timecode is sent from a government radio
station on 60 kHz?  Most would just say "ah, it's busted" and throw it
out.

I have yet to hear anyone make a case for retaining the HF system that
isn't backed by nostalgia.

As for solar flares taking out the various GNSSs ... wouldn't a solar
flare only take out the vehicles that were on the "sunny" side of the
Earth?  Wouldn't the (approximately) half of the SVs that are in the
Earth's shadow be unaffected?  Serious technical question - I have no
idea.

-- 
Peter Laws | N5UWY | plaws plaws net | Travel by Train!



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