[time-nuts] GPS frequency uncertainty

[Bob kb8tq]

Hi


> On Jul 10, 2019, at 4:26 PM, Hal Murray <hmurray at megapathdsl.net> wrote:
> 
> 
>> Would someone please expand on what the practical frequency calibration limit
>> might be? 
> 
> That's not quite a well formed question yet.  You need to say something about 
> the time scale.  What are you trying to calibrate?
> 
> Poke around for some ADEV curves.  Find one for your device (or similar) and 
> another for a GPSDO.
> 
> Most devices will be V shaped.  The GPSDO curve will go down to the right.  
> Where do they cross over?

How hard do you want to work at tracing this and that back to Paris? Ultimately 
there is a connection that can be followed back. You then get into the somewhat
rhetorical debate of “is it really that time when the official stamps it as such?”. 

On a more practical basis, most typical GPSDO’s start to struggle in the 40K to 
170K second range. A lot of things start to “bleed” into the solution. Just what 
comes in is always going to be a “that depends” sort of thing. Right now sun spots
aren’t a big deal. They will be in a few years …..

Bob


> 
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