[time-nuts] nuts about position (cheap receiver)

J Grizzard elfchief-timenuts at lupine.org
Thu May 3 13:13:47 EDT 2018

On 5/3/2018 9:26 AM, Mark Sims wrote:
> Those results were with the "ultra rapid" orbits.  It will be interesting to see what they look like when the final precise orbits are available in a couple of weeks.
> I also need to see how those values compare to Lady Heather's precision survey results.

FWIW, a dual-frequency PPP run I did late last year has the following 
uncertainties, when processed with the various IGS precision 
ephemerides, via AUSPOS:

                 longitude           latitude          altitude
IGS UltraRapid     0.004m 0.003m            0.013m
IGS Rapid          0.004m 0.003m            0.012m
IGS Final          0.004m             0.003m 0.012m

The computed ECEF coordinates change by 0.003m(X) and 0.001m(Z) between 
UltraRapid and Final.

...so really not much of a difference between UltraRapid and Final, at 
least for a dual-frequency survey at my location.

*digs through old stuff*

Okay, found a single-frequency survey from mid-last-year, processed by CSRS:

                 longitude           latitude          altitude
NRCan Rapid        0.103m            0.121m 0.253m
IGS Final          0.103m             0.121m 0.252m

...not much difference there, either.

Both of these were with a roof-mounted antenna and a good skyview, 
running 24 hours. The first was one measurement every 15 seconds, the 
latter one measurement per second. (I think for these purposes, one 
measurement every 15 seconds is more than sufficient and makes the files 
process *so* much faster).


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