CORS Tie
Posted By J.D. Billings on 10/3/2000 at 12:58 AM

I downloaded what I thought should be 11 hours of CORS data (sta PATT). Tried twice and only got 6 hours. Not sure what the problem could be, other than some kind of short circuit between the back of my chair and the keyboard.
Anyway, I processed the data, with only 6 hours, and my adjusted coords were out about a foot in both x and y, and z was about 9 feet. This CORS station is about 65 miles away, and I was using a LOCUS L1 receiver. I have plenty of quality stations in my immediate area, so the CORS capability (especially with only single frequency) is not important. Just curious if we can get better results with this CORS station and LOCUS. If so, anyone want to give some step by step advice? We'd really appreciate it.

Thanks
J.D. Billings



Re: CORS Tie
Posted By Seism Seism on 10/4/2000 at 3:55 AM

I think your accuracy at 17 miles from the CORS would be about .4 ft horizontal and 1 foot vertical. This is the stated accuracy of the locus system at 17 miles, and my testing verifies this.

However, it is my understanding that when the baselines exceed 16 miles or so other factors having to do with the atmosphere toss your positions around somewhat.

I know its nice to download CORS, hell its a free receiver on a known point, but at 65 miles, you are gonna just have to settle for loose positions.





Re: CORS woops
Posted By Seism Seism on 10/4/2000 at 4:00 AM

Woops, I meant at 17 miles your accuracy would be 0.11 horz and 0.15 vertical. THATS what I get from my local CORS.

At 65 miles the projected accuracy would be .4 horizontal but thats given no atmospheric wiggles.

The locus is very accurate, but you can't push it out that far without knowing the limitations.



Re: CORS Tie
Posted By J.D. Billings on 10/4/2000 at 11:33 AM

Seism,

I am aware of the limitations of Locus, and L1 in general, concerning the use of distant points. I did reprocess the data several times and found that using NAD83 CONUS in Geodetic format, ellipsoid and meters as parameters throughout process and adjust(and changing the settings to SP for final output), I was getting results of about 1 foot or less in X, Y and Z. At 65 miles, that's not bad, although I can think of no immediate practical use for 1 foot accuracy, especially considering 8-10 hours of receiver time to obtain those results.
I'm still not sure if I am using the best method of processing data with CORS though. Any suggestions?

Thanks

J.D.