Good afternoon all. So I've been playing with the base unit of our Topcon HiperLite+ system to collect and submit to OPUS for some rapid-static processing. We've never used OPUS but are trying to get comfortable with it to keep from chasing established monuments with our ProMarks.
Anyway, I occupied a point previously established using our ProMarks and processed with Solutions 2.7. The horizontal checked by 0.02' but the vertical was off by 0.70'. Any thoughts? I ran a 30 minute session on the point with the Hiper and have double checked antenna heights. I submitted to OPUS at 3 hours post survey and 24 hours post survey, same results.
Thanks for any input!
Great board by the way, like it much better than the "other" new board.
Remember, OPUS is an average of Three baseline solutions.
The answer to the question should be in what you did to process it the first time. Also, what were the statistics like on the OPUS solutions? Peak to peak, 60 day time series, all of these are going to be asked.
For my money and from the hip, I think it was the promark and the 30 minute session.
.70' sounds dangerously close to a datum issue.
:rain:
Did you wait for 24 hours before submitting? Have you verified datums? And i agree that the 30 minute session might be a culprit, too..
Caveman
On second though, it may not be an issue of datums, but geoid models. When you processed to the last known point (you said you went and dug them up) was the Geoid model the same (03, 09, 99) as was used in the OPUS solution. Also, were you only looking at the back page at the new geo-potential value for the elevation? Those are not the same and are both on the OPUS solution as well.
When we went from 99 to 03, there was a 0.32' shift here. I've not checked it since 03 to 09, but if it were the same, it' be dang close to 0.7'
my 2 cents, OPUS -RS is up to 9 base lines, bad 60 day series can be checked and you could omit that/those bad ones using the options. Like others have said, check the quality of the submission. Run it again for an hour and 50, resubmit, and you may well feel a warm and fuzzy
Caveman
> On second though(t), it may not be an issue of datums, but geoid models.
Kris beat me to it. Check to make sure the same geoid model was used.
After that I'd be checking on the veracity of the monuments you held in your static resolution.
Hey Bob in NH-Not to hijack the thread, but what kind of transit is that in your picture off to the right? It's been over 30 years but I'm thinking K&E? The color reminded me of an early 70's Fennel Kassel I used for a short time, but that was a theodolite.
actully one of the last Gurley's, op-62-20. yup has an optical plummet, I have a Gurley 1917 mountian transit. An example of the old stuff and wanted one of the last ones to offset it. To me it was always a K&E paragon, black, 20 sec. ver., that I used in 68 and with the Sea Bee's in70. Pre Gammon reels, I'm 62 yoa, I'm old!
Process Your OPUS Static Yourself Against the Same CORS
And compare the elevation with OPUS and with your ProMark solutions.
OPUS had a problem with certain Topcon receiver antennas and gives an elevation about 0.70' off. It has been some time since I processed several Topcon files in Ashtech Solutions and was matching the elevations with the elevations the different surveyors got from their Topcon solutions. The files and results were sent off to NGS which they reviewed. They could not figure out why and they even went to the trouble to check the antenna data OPUS was using. To the best of my knowledge they have never figured out the problem. It is very noticable if you have different Topcon receivers. At least one Topcon user swapped his receivers on pairs and OPUS always had trouble with the elevation on the one type.
Check the archives over at POB, general and Topcon.
Also check the Geoid03 against the Geoid09 elevation. Resubmit your Topcon file, go to "Options" and select Geoid03.
Paul in PA
Wow. Thanks for all the input everyone. I've had a couple brewskis this evening so I'll have to wait until tomorrow to put it all together in my head!
CC
It might be a combination of everything. Did you do only one 30-minute observation? If so, in my opinion that is not long enough. NGS publishes a recommended procedure.
