[time-nuts] WWVB Measurements using DSP recovery

[Bruce Griffiths]

Chris Albertson wrote:
> On Tue, Mar 29, 2011 at 7:13 AM, J. Forster<jfor at quik.com>  wrote:
>    
>> Even if you can build a perfect receiver I don't see how you can get
>> around the variable path length issue short of averaging WWVB for days or
>> weeks.
>>      
> Yes but you only have to wait once as long as you don't turn it off.
> This is OK if the use is only for a second independent reference.
>
> Remember the Hubble mirror problem?  I think the best use of WWVB is
> to prevent an embarrassing problem like that.   That's where they
> trusted their supper arcuate machine so much they did not bother with
> even a simple and cheep backup test.   (Even I could have seen those
> errors in 10 minutes using 19th century techniques like the Foucault
> knife-edge test)
>
>
>    
Actually the interferometric Hartmann test would have been far better 
and quicker as it only requires a simple aperture array and a camera an 
error of 1mm or so in location of the plate would have made little 
difference to the results. This method was used to guide the figuring of 
the NOT.

Bruce