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    Re: Extremely poor conditions??Atomic Clocks
    From: Alexandre Eremenko
    Date: 2012 Mar 24, 09:28 -0400

    Bill,
    Thanks for the reference.
    I conclude from your message and other messages that one cannot rely
    on a radio clock for Cel Nav.
    From the very begining, the idea of controlling a clock automaticaly
    by radio looked weird to me. Indeed, unless really well designed,
    such clocks would be unreliable.
    But WELL-designed electronic clock does not need any radio signals.
    
    However, it seems that in the specific case of our observations
    in St Joseph, MI, some doubts remain, and I don't see a way to solve
    the question, what really happened: one of the two rare things hapened:
    either the clock was 1min off or we observed some extraordinary
    refraction.
    
    I think that the first thing is more likely, Bill thinks otherwise.
    And there is no way to decide.
    
    Alex.
    
    On Sat, 24 Mar 2012, Bill Noyce wrote:
    
    >
    > You can find details on how WWVB transmits the time at
    > http://www.nist.gov/pml/div688/grp40/wwvb.cfm
    > Summary: it sends the complete time and date every minute, but the coding 
    doesn't include any form of error-correction.  Dropping one bit of data could 
    certainly make a clock lock on to a time that's off by 1 minute (or 2, or 4, 
    or 8, or 1 day,  etc).  But I would expect a well-designed clock to gather 
    data for several minutes and check it for consistency -- there's plenty of 
    redundancy if you do that!
    >  -- Bill N
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