[time-nuts] GPS position averaging

[Bob Camp]

Hi

> On Dec 15, 2014, at 9:39 PM, Paul <tic-toc at bodosom.net> wrote:
> 
> On Mon, Dec 15, 2014 at 8:35 PM, Bob Camp <kb8tq at n1k.org> wrote:
> 
>> So the question - If they are not going to be equal, which one do you pick?
> 
> 
> The better one.  If the math is sound the presumably the better position
> results in better time.
> If there are correlated defects then I suppose the GPS provided solution
> may be better.
> 
> None of the various surveys for my primary antenna (which is not optimally
> located) agree and all are "wrong" compared to carrier phase solutions.
> The delta between the various units (Trimble, uBlox and whatever is in the
> Fury) is greater than the delta between my indoor and outdoor antenna
> positions in xy.  Z not so much.


I have seen cases where almost all the error is in Z and the X and Y agree quite well. My *guess* has been that most users don’t fly. The Z error is less of a problem for them. 

Numbers in the 10’ range are not at all uncommon. That’s enough to potentially  add a 10 ns ripple to your data.

Bob

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