[time-nuts] WWVB BPSK Receiver Project?
michael batchelor
batchelormr at yahoo.com
Sat Mar 24 00:49:45 UTC 2012
OK, John Forster and I have been kicking around a few things off line, and he
suggested I should bring part of it back on line. Maybe I have a few details
wrong, or maybe I have them right and some folks are unaware of them.
My concern about the BPSK, and breaking my Spectracom oscillator, is really
centered on loosing my NIST traceable reference oscillator. I don't care one
bit what time of day it is.
I wrote:
>> I did poke around a bit, and it appears that WWVB is still an approved
>> frequency standard, so any oscillator which is phased locked to WWVB
>> qualifies as an "NIST traceable" standard
>> reference oscillator, which is my only concern.
John wrote:
>Good news! Thanks.
I wrote:
>> A GPS disciplined oscillator, regardless of how stable/accurate it may be, is
>> not an NIST traceable standard unless NIST decides to certify the Naval
>> Observatory as a standard. Or I suppose NIST could take over the GPS
>> correction uploads.but I don't see that happening any time soon. That's
>> really outside their mission boundary.
Maybe a few things have changed in the metrology world in past few years, but the
GPS based oscillators are controlled by the Naval Observatory clocks, not the
NIST clocks. So while an HP-117 or a Spectracon 8160 oscillator phase locked to
WWVB is "by definition" an NIST traceable standard so long as it is in lock and
you have a valid lock history, a GPS unit, even though it may be just as stable an
oscillator, isn't an NIST traceable standard without a whole lot of equipment to
validate that NIST and the GPS system are in sync.
(There is/was actually a commercial solution to verify this, but it isn't/wasn't cheap.)
For all you metrology guys out there, has any of this recently changed?
So my interest in keep my Spectracom going isn't just to keep a "stable" 10 MHz
oscillator in the lab. The GPS will give me a stable signal. My interest is in keeping
a "stable and "traceable" 10 MHz signal going. After all, all our old gray-hair tax
dollars paid for this government service over the past 5 decades. Why should we
get kicked off the bus now? It isn't like we want anything new. Just don't break
what we've already paid for.
Michael
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