[time-nuts] Cal standards, WWVB, etc. was Re: WWV and legal issues

David G. McGaw david.g.mcgaw at dartmouth.edu
Thu Aug 30 14:19:46 EDT 2018


Unfortunately, when they changed the format of WWVB recently to include 
phase-modulated data it broke all the receivers that had used it as a 
frequency standard, so we cannot use that argument.  A receiver to lock 
to the new format has been documented here, but there may be only a 
handful actually in existence.  For those looking for that type of 
standard, it may be better to rely on the Navy VLF transmitters such as 
NAA on 24kHz.  Who knows, but I expect they are not up to be defunded.

David N1HAC


On 8/30/18 1:23 PM, jimlux wrote:
> On 8/30/18 8:15 AM, Mike Bafaro wrote:
>> According to what I have heard the 60KHz WWVB carrier is guaranteed 
>> accurate to the atomic standard and is considered traceable.  I 
>> remember when I was in the Navy years ago I remember taking our 
>> unit's HP5245L for calibration and they used a VLF tracking receiver 
>> at 60KHz to do the calibration.  If WWVB goes off the air what is the 
>> replacement for the 60KHz standard?
>>
>> Mike
>>
>
> The 5245L is a 1960,70s vintage thing so I assume you were doing those 
> cals 40 years ago when inexpensive atomic standards like the SRS FS725 
> didn't exist.
>
> These days, I suspect that a $3000 Rb box or a GPSDO would have 
> sufficient accuracy for this sort of thing as a transfer standard, and 
> would be traceable.  I can't imagine that a "over the air" signal 
> recovered from WWVB would be better than either of those two.
>
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