Monitoring
Posted By Daniel Hoekstra on 8/21/2001 at 2:56 PM

I'm measurng 3-5 kilometer Baselines
10+ minute occupations
I'm using Z-12 receivers
several times now I've experienced positional errors of about 2 to 3 centimeters, they do not seem to be due to multipath.
Normally this would not be a problem
but in dam monitoring this is too much
I'm open to suggestions and to Ideas as to the cause of these errors, they seem to be about twice what I would expect



Re: Monitoring
Posted By Bob LeMoine on 8/21/2001 at 3:09 PM

Daniel,

If your looking to obtain sub-Cm solutions on your monitoring points, I would recommend increasing your Observation times.

Observations of around 10+ minutes may not be sufficient to yield the results you desire. You may want to also consider using Precise Orbits in the Baseline processing.

Bob LeMoine
Thales Navigation
Ashtech Precisin Products


Re: Monitoring
Posted By Brian D. Ewing, PLS on 8/21/2001 at 3:18 PM

We are currently in a period of high solar activity. This means unfriendly ionospheric conditions for GPS users. While dual-frequency receivers can compute the ionospheric delay, scintillation is still a problem and does have adverse effects. As Bob said, try increasing your observation time. You might also look at other postings here and on the main message board for info sources on space weather conditions, and see if there was anything happening when you made those observations.