The 4.5 hour session with the antenna 1.5 meters above the mark, compared to the first one at 0.5 meter, was only slightly better in observations used or ambiguities fixed, and ellip ht still 0.3 m pk-pk.
The shorter simultaneous session out in the open some 30 yards away used 97% observations and had ellip ht pk-pk 0.027 m.?ÿ So no interference during that time.
My conclusion is that the tree is just too much of a problem, even leafless.?ÿ I don't think the cannon metal would affect the reception with the ground plane 1.5 meter above it.
We had a wind storm last fall that took out 65% of the big trees in town.?ÿ I wish it had taken this one instead of several others nearby.?ÿ Or maybe I don't - it could have landed on the cannon and broken the concrete.
?ÿ
Did you record more than US satellites? If so try Trimble RTX post processing. It??s free. OPUS uses only US satellites.
The goal was to submit to OPUS Share for the NGS GPSonBM program.?ÿ OPUS only uses GPS for now.
I commend your efforts to provide ellipsoid heights on bench marks. Too bad the effort is not more universally recognized as useful.?ÿ
GNSS signal is reflected off the ground. ?ÿThere are efforts to take advantage of these ground reflections to study phenomena like soil moisture levels.?ÿ
Have you reviewed the plots generated using the ??qc? option in teqc? You need a navigation message as well as the observation file. teqc creates multipath and signal-to-noise ratio plots. I used to use the old command-line version a lot. I understand that the QCVIEW32 program no longer works.
As I recollect you use a Trimble 4000SST receiver, I am curious how well the integer fixing works with the squared L2 observable.
Both links and abstracts are to same research effort. Unfortunately, I do not have a URL for the entire paper by Larson.?ÿ
https://link.springer.com/article/10.1007%2Fs10291-007-0076-6 ?ÿ(
?ÿ
See:
Agreed, however the RESET process would be allowed and then do a GPS on BM observation on the RESET mark. That's the long, tedious and NGS way. Another "poor man's" way is do a shares on the eccentric and post the leveled elev. in the mark description noting its tied to the vertical face or obstructed BM. It won't be used as a GPS on BM tie by NGS but it could have the same benefit for local users for connecting to passive datum marks.?ÿ
I have 4000sse receivers.
I started with the sst but it does not meet the project requirements.?ÿ I was able to get some shaky OPUS positions with it, as training that gave me confidence to upgrade.
I don't seem to get nav files nowadays when using teqc, so some of the diagnostic info is lost. I mean to work on that, as I don't know if I lost something in my .bat files or if it is a consequence of being past week 2048. I may have to learn how to get the .nav from elsewhere.
I tried to install Fixweek and locked up the old computer that I use for serial transfers, probably from an operating system mismatch on the .dll it wanted to upgrade. I had to do a "repair" operation using a Win install disk to recover.
So it's a shaky operation here.
The collective inhaled breath over at the Potomac probably created a bunch of tornados.
You heathen! You didn't run a first order loop! You didn't bluebook that nail! It is all useless!!! Why are you trying to pollute our pure data???!!!???
Pretty much a quote from when I asked this sort of question in a conference.
At that point I just shut up and didn't try bringing up that a benchmark from 100 years ago might have some issues beyond the hundredth I might mess up, nor that we are chasing feet not hundredths (sorry millimeters).?ÿ
As always, attempting to present common sense to a bureaucracy is an exercise in futility. What is common sense in a world where profit and production and results are paramount is completely nonsensical from the perspective of a bureaucracy.?ÿ
Put the pole close and call it centered??ÿ
Not fully advocating this, but for the purposes of the work being done, it MIGHT (and for all my comments earlier, I defer to NGS's expertise) be fully adequate.?ÿ
Getting it centered would be fairly easy, however. Simply calculate the lean, or put up a ladder and drop a plumb bob from the head to the BM, and have a helper adjust the rod lean.?ÿ
Perhaps a 12' rod.
But, it might not be stable for 4 hours.
It might be interesting to see if RTX has the same issues...
I have found that RTX does not work well at all for GPS only, unless you have very long sessions. It works best with three or four constellations (although I don't believe it is using Beidou currently, as the output I get back always lists GPS, GLONASS, and Galileo but never Beidou).?ÿ
I believe Bill93 is using a GPS only receiver.?ÿ
Bill,
email me your latest RINEX file, I would like to get a look at your observables.
One thought, are there lightning rods or supporting cables in those close trees? If not that the cannon could be acting like a giant grounding rod and is sucking the GPS signals right past your antenna
Paul in PA
on the issue of the navigation message, this file is available via the User-friendly CORS link on the NGS home page.
??one can obtain the following files for a site??s data:
?ÿ
Bill,
I received your file and was surprised to see 9 satellites from the start, however your older receiver is slow to figure out ambiguities and there was quite a bit of no L2 data at the beginning. I removed the first 4 minutes and submitted it to OPUS, which is slow today. I note that near the end you drop to 5 satellites which may be because you blocked satellites that were coming into view. The early data looks good enough to submit to OPS-RS and will do so after I see how OPUS likes what I did so far.
Paul in PA
I had warmed up the receiver at home so it had a current almanac, and was lucky on the time to get so many sats. I don't understand why L2 would lag L1 though.
I think I had all the right ones enabled in the later portion. I was trying to keep up with a mission planning site on my phone, to disable sats that weren't visible and enable them before they became visible. The planner doesn't show a serious reduction in number, so maybe I didn't get it right.
I started with all enabled, and began messing with disables after setting up the open-sky receiver. I got lost reading the small screen so disabled some good ones. I realized it when rechecking the open-sky receiver and seeing it was getting them, so hurried back and re-enabled them. So there is a span of about 4 minutes near 2015 UTC with few sats before I got it corrected.
Learning experience-make a schedule while at home, not on the phone
I sat down and compared the planning tool with the sats observed.?ÿ Sats 3 and 22 were rather low elevation angle so not surprised I didn't get them.?ÿ
Sat 6 should have been used after 2110 UTC but I did not pick it up. I had it marked to be enabled after 2100, and thought I enabled it, as it is noted on the last scratch paper list I made. It was the only one missing that I should have seen.?ÿ
Everything else the tool says should be received was in the file.
The results I got below are better, but when I get time I will improve the file a little more.
A legacy receiver locks on to the L1 signal first then dithers around before ascepting the L2 signal. Newer receivers are much better at the math and use different algorithms. Having L5 available also speeds up the newer receivers, while some also start with the new L2C signal which the older receivers know nothing about.
Paul in PA
?ÿ
FILE: MARN2160.21o OP1616589629316
?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿNGS OPUS SOLUTION REPORT
?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ========================
All computed coordinate accuracies are listed as peak-to-peak values.
For additional information:?ÿ https://www.ngs.noaa.gov/OPUS/about.jsp#accuracy
?ÿ?ÿ?ÿ?ÿ?ÿ?ÿUSER:?ÿlplopresti@enter.net?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿDATE: March 24, 2021
RINEX FILE: marn079t.21o ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿTIME: 15:28:05 UTC
?ÿ?ÿSOFTWARE: page5 ?ÿ2008.25 master95.pl 160321 ?ÿ?ÿ?ÿ?ÿ?ÿSTART: 2021/03/20 ?ÿ19:08:00
?ÿEPHEMERIS: igr21496.eph [rapid] ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿSTOP: 2021/03/20 ?ÿ23:35:00
?ÿ?ÿNAV FILE: brdc0790.21n ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿOBS USED: ?ÿ5532 / ?ÿ9696 ?ÿ?ÿ: ?ÿ57%
?ÿ?ÿANT NAME: TRM14532.00 ?ÿ?ÿ?ÿ?ÿNONE ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ# FIXED AMB: ?ÿ?ÿ102 / ?ÿ?ÿ137 ?ÿ?ÿ: ?ÿ74%
ARP HEIGHT: 1.5 ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿOVERALL RMS: 0.028(m)
?ÿREF FRAME: NAD_83(2011)(EPOCH:2010.0000) ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿITRF2014 (EPOCH:2021.2161)
?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ
?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿX: ?ÿ?ÿ?ÿ?ÿ?ÿ-132401.958(m) ?ÿ?ÿ0.086(m) ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ-132402.893(m) ?ÿ?ÿ0.086(m)
?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿY: ?ÿ?ÿ?ÿ?ÿ-4742876.796(m) ?ÿ?ÿ0.192(m) ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ-4742875.448(m) ?ÿ?ÿ0.192(m)
?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿZ: ?ÿ?ÿ?ÿ?ÿ?ÿ4248467.216(m) ?ÿ?ÿ0.122(m) ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ4248467.128(m) ?ÿ?ÿ0.122(m)
?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿLAT: ?ÿ?ÿ42 ?ÿ1 58.28999 ?ÿ?ÿ?ÿ?ÿ?ÿ0.066(m) ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ42 ?ÿ1 58.31652 ?ÿ?ÿ?ÿ?ÿ?ÿ0.066(m)
?ÿ?ÿ?ÿ?ÿ?ÿE LON: ?ÿ268 24 ?ÿ3.41503 ?ÿ?ÿ?ÿ?ÿ?ÿ0.081(m) ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ268 24 ?ÿ3.37277 ?ÿ?ÿ?ÿ?ÿ?ÿ0.081(m)
?ÿ?ÿ?ÿ?ÿ?ÿW LON: ?ÿ?ÿ91 35 56.58497 ?ÿ?ÿ?ÿ?ÿ?ÿ0.081(m) ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ91 35 56.62723 ?ÿ?ÿ?ÿ?ÿ?ÿ0.081(m)
?ÿ?ÿ?ÿ?ÿEL HGT: ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ226.762(m) ?ÿ?ÿ0.203(m) ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ225.722(m) ?ÿ?ÿ0.203(m)
?ÿORTHO HGT: ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ258.970(m) ?ÿ?ÿ0.242(m) [NAVD88 (Computed using GEOID18)]
?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿUTM COORDINATES ?ÿ?ÿ?ÿSTATE PLANE COORDINATES
?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿUTM (Zone 15) ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿSPC (1401 IA N)
Northing (Y) [meters] ?ÿ?ÿ?ÿ?ÿ4654373.813 ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ1060957.894
Easting (X) ?ÿ[meters] ?ÿ?ÿ?ÿ?ÿ?ÿ615964.742 ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ1657401.719
Convergence ?ÿ[degrees] ?ÿ?ÿ?ÿ?ÿ0.93811944 ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ1.28835833
Point Scale ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ0.99976547 ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ1.00000631
Combined Factor ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ0.99972991 ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ0.99997075
US NATIONAL GRID DESIGNATOR: 15TXG1596454373(NAD 83)
?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿBASE STATIONS USED
PID ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿDESIGNATION ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿLATITUDE ?ÿ?ÿ?ÿLONGITUDE DISTANCE(m)
DP1249 IATA IOWA DOT TAMA CORS ARP ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿN415801.646 W0923305.032 ?ÿ?ÿ79241.8
DP1318 IAMN IOWA DOT MARION CORS ARP ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿN420149.083 W0913255.556 ?ÿ?ÿ?ÿ4174.0
DP1251 IAWN IADT WASHINGTON CORS ARP ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿN411834.119 W0914044.748 ?ÿ?ÿ80621.9
?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿNEAREST NGS PUBLISHED CONTROL POINT
NJ0542 ?ÿ?ÿ?ÿ?ÿ?ÿMARION ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿN4201000058 W09135000056 ?ÿ?ÿ?ÿ?ÿ?ÿ?ÿ4.3
This position and the above vector components were computed without any
knowledge by the National Geodetic Survey regarding the equipment or
field operating procedures used.
?ÿ8002 ?ÿ?ÿWas this collected on a published mark? Please help update
?ÿ8002 ?ÿ?ÿNGS records by sharing?ÿ https://geodesy.noaa.gov/marks/sharing/ ?ÿor
?ÿ8002 ?ÿ?ÿupdating descriptions?ÿ https://geodesy.noaa.gov/marks/recovery/
Pk-pk el ht is still 2.5 times acceptable 8 cm for sharing, which is pretty bad, and I thought I remembered GPSonBM recommended better than that. The 57% and 74% are a little better, but poor.?ÿ?ÿ
What other tricks do you have??ÿ?ÿ I can imagine getting the % used up by deleting some of the ragged edge entries as sats come and go, but I don't expect it will help pk-pk enough.?ÿ
I doubt this is salvageable, and I wouldn't have enough confidence to submit it unless the vertical pk-pk was under 4 cm.
Bill: not sure if you mentioned it, but what was the difference in ellipsoidal heights for each solution? Sometimes high peak-to-peak values can be cause by inaccuracies in the CORS coordinates. Not likely, but a possibility. And were the same CORS used each day??ÿ
I removed 15 minutes of sloppy data from the end but the peak to peak got a little worse, so that extra 15 minutes was still valuable. The rest of the ambiguities are scattered throughout and may not be worth the effort. I note that OPUS says your mark is 4.3 meters away from the GPS values. I say that is far in excess of the OPUS peak to peaks so you may not want to put too much faith in the datasheet. I note that the ortho height is within the peak to peak error.
Paul in PA
