[time-nuts] NIST Traceability [WAS: WWVB BPSK...]

[Charles P. Steinmetz]

Michael wrote:

>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.     *   *   *
>
>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.      *   *   *
>
>For all you metrology guys out there, has any of this recently changed?


These NIST links should get you started:

http://nist.gov/traceability/

http://tf.nist.gov/general/pdf/2297.pdf

http://www.nist.gov/pml/div688/grp40/gpsarchive.cfm

<http://www.google.com/url?sa=t&rct=j&q=&source=web&cd=1&ved=0CEEQFjAA&url=http%3A%2F%2Ftf.boulder.nist.gov%2Fgeneral%2Fpdf%2F1502.pdf&ei=CmRtT9fSB4ji0gGAm7n_Bg&usg=AFQjCNGO0uxF4gdRhld-L8PEERwEmaGgGg>


Note that only *measurement results* are "traceable" -- not local 
standards.  There is no such thing as a "NIST traceable 
standard."  And even with a WWVB reference, one needs an "internal 
measurement assurance program" to support a claim of traceability for 
the measurements that one makes.  Just having an HP-117 or Spectracon 
8160 is not sufficient to claim NIST traceability for one's 
measurements.  Note that less than 1% of claimed "NIST traceability" 
really is traceable to NIST.  For all the stuff on eBay that claims 
to be "NIST calibrated" (Really?  Did you take that to Boulder for 
calibration?) or "NIST traceable," only a negligible amount of it really is.


Best regards,

Charles