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Iowa RTN
I would like to hear from people that are using the Iowa GPS network. Has it been reliable? How good (repeatable) are the positions, or coordinates that you get?
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5 Replies
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I don’t actually use the system yet, so cannot comment on the usefullness of it or the repeatability of position data.
But, I am on their email list and it seems there have been several times when the system or part of the system is down due to one reason or another. They normally seem to get it back up and going fairly quickly – as far as I can tell form the emails. Like I said, I don’t actually use it.
Some day we hope to upgrade our equipment to be able to use the system. Our Topcon Hyper-Lites will not work with it – something about the boards inside. Heck, they only seem to work half the time anyway – we have been having ongoing range issues that our local dealer has had a hard time trying to resolve.
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2d coordinates (N,E) are repeatable at about the 0.05 ft std error level on 95% of fixed observations. 3d (Z) is a different story. We cannot recommend using the network for repeatable vertical unless 0.30 ft error is acceptable. Out topo crews use a base/rover arrangement for acceptable error levels. This was not the level of vertical error that the network was designed for or what was specified. The vendor and the network administrator are aware of the issue and are looking for solutions. The vertical repeatability went haywire about May 1 when there was a Glonass outage for a few days. Glonass returned but the previous repeatability did not. Even with GPS only. Also the time to fix has been irregular and sometimes irritating. On the other hand its a free service so if you have the equipment anyway you might as well subscribe. There is also a network static survey on line computation service for registered users where the peek to peek errors are substantially less than OPUS solutions because the reference stations are much closer.
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Washington RTN
I hit a WSDOT benchmark, the other day, the published NAVD88 Ortho height was 15.622m, the results I got were 51.255 US survey ft. Yep, that’s about a .002′ difference.
Probably compensating errors, but it still looks good on paper;-)
Have a great day, I know I will.
Dugger
I hope everyone has a great day; I know I will! -
Oregon RTN
I ran a little test with Oregon’s network (ORGN) in our parking lot. First I OPUS’d a point twice with 4 hour sessions, and used an average. Then I recorded the same point using the ORGN with various occupation times. ORGN positions agreed with the OPUS within 0.05′ or so right down to 1 second observations.
Expect your results to vary with PDOP.
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Oregon RTN
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> Expect your results to vary with PDOP.Marks right, you need to be in the right place, at the right time;-)
That’s what GPS is all about.
Have a great day, I know I will
Dugger
I hope everyone has a great day; I know I will!
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