[time-nuts] The USFS Frequency Standard...
kb8tq at n1k.org
Fri Feb 10 19:26:50 EST 2017
The simple answer is that WWVB still has the good old AM modulation on it.
Any of the old *time* receivers will work just fine with the current broadcast
format. There are a number of them that show up on the surplus market. The
gotcha is those receivers that wanted to get both frequency and time. Those
are toast without some heroic modification efforts.
The world is still waiting for the magic chips that will decode the new format
to show up on the market. The issue is that you *could* do a design that uses
a hundred dollars of parts. Poof! you have a commercial device to sell.
Next day out come the magic chips for < $1 and 80% of your BOM is replaced.
Your competitor now has a unit on the market for 1/5 your price. You better *hope*
you recovered all of your up front costs before that happens. You also now have
a group of customers that expect at least 20 years of free updates and free support
on your gizmo ….and it’s a dead end for you. Zero dollars in on that design and many
many dollars out every year. Simple answer is not to go down that road. Wait for
the magic chips to show up. That’s the way it’s worked for at least 40 years.
Basement lab wise, sure you can come up with this or that to demodulate the signal.
That’s been done and is being done. That’s a long ways from a commercial rack mount
gizmo that “just works”.
On a more practical basis, GPS is traceable to UTC and to USNO. By law USNO is the
authority on time in the US. NIST is the authority on frequency. That distinction goes back
to a long gone era when time was a “navigation” thing and frequency was a “commerce”
function. In either case, you need to be able (legally) to trace via a valid path to whatever
each of them say is correct. These days there are *lots* of paths. They all work and all
have tolerance estimates on them. On a global basis you need to trace back to UTC and
BIH. It’s the same idea only one level higher.
> On Feb 10, 2017, at 3:47 PM, Burt I. Weiner <biwa at att.net> wrote:
> Technically speaking, the United State Frequency Standard (USFS) is still considered to be transmitted via WWVB on 60 kHz, essentially making WWVB the USFS. But is WWVB still a usable frequency standard reference since they've gone to phase shifting their signal for time keeping purposes? Will GPS become the "official" USFS reference signal?
> Is there a 60 kHz WWVB receiver out there that can still be used as reference? Is there a commercially made receiver out there that now uses the phase shifting technique of WWVB for accurate time keeping?
> Have I missed something?
> Burt, K6OQK
> Burt I. Weiner Associates
> Broadcast Technical Services
> Glendale, California U.S.A.
> biwa at att.net
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