[time-nuts] nuts about position

Bob kb8tq kb8tq at n1k.org
Sun Jun 3 17:30:14 EDT 2018


Location will always impact things a bit. At some point it does become a minor 
contributor. What point that is varies with a lot of things. One of them is indeed
the propagation path to the satellites. 

How much the ionosphere and troposphere mess things up is very much a “that depends”
sort of thing. There are corrections applied to the data as part of normal GPS L! operation.
The degree to which these corrections work depends on how close things are to the “normal
model”. That in turn depends to some degree on how active the sunspot cycle is at the time.
Right now we are in a period of relatively low activity. That equates to the models mostly fitting
better most of the time.

If solar activity was somewhat higher, then things get more dynamic. The magic models and 
the broadcast data can’t keep up as well. That translates to more noise on the estimates and
worse timing ( as well as an impact on location). 


> On Jun 3, 2018, at 4:07 PM, Chris Caudle <chris at chriscaudle.org> wrote:
> On Sun, June 3, 2018 12:57 am, Mark Sims wrote:
>> Well,  with a little prodding and help from Magnus,  I now have the
>> Trimble devices outputting RINEX files.
> Is this applicable to a Thunderbolt, and would this improved position
> accuracy be expected to improve the time accuracy from a Thunderbolt
> compared to using the older Lady Heather 24 hour self survey method?  Or
> is ionospheric noise the limiting factor so determining more accurate
> position doesn't really help?
> -- 
> Chris Caudle
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