Jimbo posted his HARN results..

N 627294.358
E 2686221.955
El 46.376

Mine
N 627294.894 (0.53 feet)
E 2686221.552 (0.403 feet)
El 44.805 (1.57 feet)

I really wouldn't be comfortable with my solution at all...Seems that Jimbo (from looking at the data) was very noisy (or was swaying pretty badly)..

Input Jimbo? Was the anntenna affixed that allowed some wind movement.The data sure seemed to be all over the charts....

Now on to POST!

TM

(almost sounds like a soap opera dialog)

It's possible their is some sway...but it was a fairly calm night (while I was awake anyway) so I don't think there was much, if any.

Just the fact it is a pole in the air does increase the possibility of movement but I think it is fairly stable.....

4.5" od pipe 17' tall, 5'± inground and attached to mated pipe 4'away-
2" od pipe 21' long-
coupling-
6" nipple and cap with mounting plate welded to it.

pivot point 16' up 4.5"pipe and 12' up 2". Bottom of 2" locks to 4.5", 4.5' above ground. There is about 10' of "unsupported" 2" (elevation 36-46) with whatever a Locus weighs plus the x-sec area of the pipe to create movement. Yeah, some is possible but it ain't gonna be a lot, I don't think.

I'll try and get a picture up this week so ya'll can have a basis to form an opinion.

The first few minutes and the last few have signifigant movement (10') due to the mount and dismount procedures.

HARN Session - 8 sats - 45minutes ±
95% <.02 H <.04 V

I've run a loop to VINTON Harn ...
and CIVIC. Should have a 4 hour± session from Vinton to Jimbo.
about 25 miles. Also used two different intermediate points, 1 coming and 1 going, each about 1/2 way but they are about 2-3 miles apart, each has a 2 hour session). I'll finish the network probably Tues by setting a Locus on Jimbo and the 2 intermediates, then moving Jimbo to Civic to Vinton. Should take 3 hours + drive time = 5 hours. With this I should have some relatively strong vectors and x-ties.

That'll be 2 Harns. now I need to start looking Easterly.

Jimbo

PS: I'll attach a sketch in a few minutes of the network points.
Modified By James Webb on 2/17/2002 at 4:01 PM

(not to start an argument over software, but) that Ashtech Solutions is handling this type of data in a way that's more suited to "mega-vectors" with greater uncertainties?

My coordinates for JMBO were a bit closer I think (from week one of ORGI2):

N 627294.214 (95% error estimate 0.284)
E 2686222.078 (95% error estimate 0.310)
Ele. 46.128 (95% error estimate 0.221)

The error estimates seem to be somewhat in line with Jimbo's initial HARN derived position.

So, what's the deal.

I know nothing about Trimble software (and very little about mine), but could it be that as we suggested last fall, you guys may be "over scrubbing" the data, whereas we have the ability to use "Partial Solutions" (still fixed) to use more of the data? I do have some other ideas along this line of thinking, but will have to wait.

later

J.D.

Maybe like JD says, it was just a bad night..Had lots of trouble with POST also, but not as much variance in the raw data as Jimbo..
As to my comment on wind sway (when I re-read my post it indicated large sways), when actually I was wondering if 1-2cm's was possible because of the height....

Post (JD's Precise)
N683581.422
E3100685.774
El 402.799

Using Bea5-Arl5-Post (orgi)
N6835851.564 (not to bad)
E3100685.373 (almost half a foot)
El 403.843 (over a foot)

Using Bea5-Arl-Dqua-Post(orgi)
N6835851.554 (okay)
E3100685.356 (still a half a foot)
El 405.724 (ouch!)


JD...What did you think of the PaulkE-W sessions, as far as the SV residual plots...Jimbo and Post both showed very high residuals on the raw data.. Was the IONO or Tropo much worse in the SE that night?

I'll go ahead and do the PaulkE and PaulkW, but have about decided that not much more can be done on Post or Jimbo, at least with my skills and software..

I was hoping for better results,but guess we are seeing what should normally happen on the megavectors...
I think our 'squish factor' might just be to large on this one...

Actually, when comparing the misses on POST and JIMBO, both were in about the same range...0.5 feet and 1-3 feet in the elevation..

The stats actually showed that my output should have been much worse than they actually matched..

TM

I went back and opened 'it all up', no disabled SV's, mask nominal, processing style for float (didn't force a fixed solution)...Answers still about the same..
I did get the vertical much better by calculating the Elevation (using the CORS derived) and fixing these on the ARL,BEA and DQU....

Still, my software says that the results are only within 1' horizontal and 2' vertical (by looking at the error ellipses)...Maybe we need a new Trimble guy to also work on this data...

I also agree...No two software's will match entirely and there's got to be some fundamental differences...Looks like the Ashtech, as you say, can deal with the uncertain quantities in a more delicate way that produces better answers on the megavectors...Wish Kent or someone would try our data with Star*Net (completely impartial to brands) for another look at the results..Or another TGO user to check and see if I'm way off base...

TM

IMHO- I think that TGO might be constrained to 'normal GPS surveys' while the AS is a bit more flexible...when working outside the box as it were...

Deral:

I've been experimenting with the sort of positioning accuracy that can be had using L1 float solutions over lines up to about 555km. This has been as a part of the Oklahoma Movement Monitoring Program that has been partly funded by FEMA and partly by the surrounding states, all of whom seem to have understood the value of getting advance notice of any sudden movements up there.

We had been using the CORS point LMNO (Lamont, OK) as the fiducial point on the Oklahoma Tectonic Plate and solving the vectors from it to the CORS points HVLK (Haviland KS), CNWM (Conway MO), WNFL (Winfield LA), and JTNT (Jayton TX) to check for movement in Oklahoma. Unfortunately, you Oklahomans apparently got wind of this and took LMNO off line, so the program has been temporarily suspended.

What we found before then, though, is that L1 positioning appears to be possible in good space weather (K index = 1 or less) over distances up to about 500km with an uncertainty of less than +/-3cm (standard error) in N and E using:

-nightime observations (around local midnight)
- at least two CORS points on opposite sides of point to be positioned (and at approximately equal distances)
- less than 2.5 hrs. data
- precise ephemerides (IGS Rapid Orbits), and
- solving common scale parameter for all simultaneous vectors

The processing strategy that has worked well is just to process all baselines as a batch with the normal 15deg elevation mask and simply delete any particularly noisy SV's from the solution.

This is also a processing method that could be implemented for automated batch processing in an OPUS-like L1 positioning utility.

Best regards,
Kent McMillan, RPLS Austin TX
Modified By Kent McMillan on 2/17/2002 at 9:44 PM

I'll try your method...Sounds promising..I just didn't understand why Jimbo and JD were getting much better matches that I was using TGO...I am (and still) thinking that TGO was set up for surveys 'done in the box' and as we expanded, then it fell apart...

I'll try your suggestions, but please expound on common scale parameters for simultaneous vectors....

With a 15 degree mask, then many cycle slips appear...So what...Just remove any SV with cycle slips instead of editing the occupation?

Kent...All the data is out there on Jimbos FTP site if you want to jump in...

TM

PS-Oklahoma is not moving...I can tell you that from experience...My chair stays in the same spot from day to day..With or without AFP protection...

Here at the house (and FTP site) the cable has been down for .....hours.

Just came back up.

At the office I was evaluating some security encryption software....well it works so good that Acad and Xmap don't run. I reinstalled A2002 and it won't even accept the authorization code !! And this is after I uninstalled the encryption software....BTW its only supposed to work on data you tell it to encrypt ;-)

I'm not even sure if IE is working at the office. Might be reloading W2k and a few other software packs in the am.

And TM, I would say with light winds a little wobble is quite probable....

Jimbo

Deral:

In TGO, I assume that you have the option of solving transformation parameters in the adjustment. Just let TGO solve both the scale parameter and rotation parameters and see whether your results get better. The scale parameters that I've been finding have been less than 0.5ppm.

I don't know about cycle slips. In the data that I've experimented with there were not very many. Which night are you working on processing?

Thanks for the anecdotal confirmation of our preliminary finding that Oklahoma is in fact going nowhere.

Best regards,
Kent McMillan, RPLS Austin TX


Modified By Kent McMillan on 2/18/2002 at 12:26 AM