[time-nuts] improved WWVB signal being planned?

tcxo gbusg at comcast.net
Tue Mar 29 02:14:22 UTC 2011


I'm concerned that, in their quest to address the needs of the general 
public's radio clocks, NIST might overlook the frequency standards needs of 
our metrology community. (Unless the metrology community provides adequate 
feedback to NIST *before* it might be too late?)

According to their interpretations of ISO/IEC 17025, many customers require 
metrology labs to include inter-comparison procedures for assurance. For 
example, they might require a GPS disciplined house frequency standard to be 
cross-checked against another non-GPS frequency standard (for assurance 
purposes). In the past Loran-C served this need well as the alternate source 
of traceable frequency. But with the demise of Loran-C, WWVB has become more 
important for this purpose. Yes, we know that GPS out-performs WWVB for 
frequency; but within a stated uncertainty (that's adequate for many 
purposes), WWVB still supplies the alternate source of traceable frequency 
comparison.

Do any of the resident gurus of this list have opinions as to whether or not 
NIST's proposals might exclude WWVB as a source of traceable frequency 
comparisons?

At least, I think it prudent that some of us let NIST know that we're still 
relying on WWVB for traceable frequency comparison systems.

Greg


----- Original Message ----- 
From: "beale" <beale at bealecorner.com>
To: <time-nuts at febo.com>
Sent: Monday, March 28, 2011 3:02 PM
Subject: [time-nuts] improved WWVB signal being planned?


I thought this was interesting... I don't know if this had been already 
mentioned here- probably some list members are already part of the process! 
I wonder if this would be a spread-spectrum code like the GPS signal?

"[...] Another idea being actively investigated is to add phase modulation 
to the existing WWVB signal while leaving the AM BCD code intact. This would 
allow all existing devices to continue to work, but allow a new generation 
of radio-controlled clocks to be developed.  These new devices would have 
greater processing gain and therefore be capable of reading the time code 
with a lower signal-to-noise ratio."

from  "We Help Move Time Through the Air
Managers of WWVB Explore Options to Improve the Service Further"
by John Lowe, manager of NIST radio stations WWV/WWVH/WWVB.
http://tf.boulder.nist.gov/general/pdf/2504.pdf

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