Recently did about a 40 minute observation and sent the data to OPUS to process. The data returned looked a little suspect. The ortho elevation provided called for 1.878M,NAVD88 using Geoid12A. This converts to 6.16 feet. Not belieiving the elevation I did a quick check against Google Earth and it show an elevation of 8 feet. To confirm the elevation I ran to the nearest BM supposedly on 88 elevations and had an elevation of 8.12 feet. Has anyone else noticed elevation issues with OPUS lately?
Have you eliminated the possibility of a blunder? Such as a bad rod height?
Did You Enter Rod Height In Feet Not Meters ?
8 - 6.16 = 1.84 x 3.28 = 6.03 feet. So possibly it is your rod height, either not entered or in the wrong system.
I have found OPUS-RS elevations to be very good.
Also break your 40 minutes into 2 20 minute sessions and resubmit looking for some errors from other sources.
Paul in PA
What makes you think google earth can be relied on for accurate elevations? Last time I checked GE's elevations came from a 30m DEM created by SRTM. I could easily see 2 feet of difference if the area isn't really flat.
Fixed height 2m rod was used. Google earth is good for a sanity check and I did run to a NAVD88 BM. Not my first time to the rodeo.
Rod, email Me Your OPUS-RS RINEX File
Based on what you say, it appears your problem is unusual, perhaps a clue is in the observations.
Paul in PA
lplopresti (at) enter (dot) net
Rod, email Me Your OPUS-RS RINEX File
Ditto...I'd like to look at that data as well.
ldogeo at aol dot com
Loyal
Can you post the OPUS-RS solution here?
I also wonder if it's possible that the 12A geoid still has errors in it:
Yes, post the OPUS-RS report
What sort of residuals did you get for lat, long, and height?
Yes, post the OPUS-RS report
Here is the report from OPUS
FILE: log1220q.tps OP1356731717623
NGS OPUS-RS SOLUTION REPORT
========================
All computed coordinate accuracies are listed as 1-sigma RMS values.
For additional information: http://www.ngs.noaa.gov/OPUS/about.jsp#accuracy
USER: tom@tkmlandsurveyors.com DATE: December 28, 2012
RINEX FILE: log1355q.12o TIME: 21:58:50 UTC
SOFTWARE: rsgps 1.37 RS50.prl 1.86 START: 2012/12/20 16:33:15
EPHEMERIS: igr17194.eph [rapid] STOP: 2012/12/20 17:13:50
NAV FILE: brdc3550.12n OBS USED: 3600 / 3825 : 94%
ANT NAME: TPSHIPER_LITE NONE QUALITY IND. 17.10/ 51.12
ARP HEIGHT: 2.0 NORMALIZED RMS: 0.315
REF FRAME: NAD_83(2011)(EPOCH:2010.0000) IGS08 (EPOCH:2012.96914)
X: -2695606.330(m) 0.006(m) -2695607.181(m) 0.006(m)
Y: -4295037.095(m) 0.009(m) -4295035.752(m) 0.009(m)
Z: 3855698.319(m) 0.009(m) 3855698.333(m) 0.009(m)
LAT: 37 26 1.04695 0.003(m) 37 26 1.06082 0.003(m)
E LON: 237 53 14.01108 0.005(m) 237 53 13.95272 0.005(m)
W LON: 122 6 45.98892 0.005(m) 122 6 46.04728 0.005(m)
EL HGT: -30.756(m) 0.012(m) -31.291(m) 0.012(m)
ORTHO HGT: 1.878(m) 0.025(m) [NAVD88 (Computed using GEOID12A)]
UTM COORDINATES STATE PLANE COORDINATES
UTM (Zone 10) SPC (0403 CA 3)
Northing (Y) [meters] 4143346.889 604844.064
Easting (X) [meters] 578492.101 1857278.537
Convergence [degrees] 0.53932027 -0.98739234
Point Scale 0.99967589 0.99994444
Combined Factor 0.99968071 0.99994927
US NATIONAL GRID DESIGNATOR: 10SEG7849243346(NAD 83)
BASE STATIONS USED
PID DESIGNATION LATITUDE LONGITUDE DISTANCE(m)
DN7479 SLAC SLAC_BARD_CN2002 CORS ARP N372459.450 W1221215.295 8317.0
DH9021 P222 COYOTHILLSCN2004 CORS ARP N373221.249 W1220459.698 12009.2
DN7542 P176 MILLSCREEKCN2007 CORS ARP N372818.368 W1222125.650 22036.6
AF9690 CHAB CHAB_BARD_CN1991 CORS ARP N374326.805 W1220709.466 32247.4
DI0898 PPT5 PIGEON POINT 5 CORS ARP N371113.498 W1222323.779 36774.5
DM7563 P534 COOKEPEAK_CN2007 CORS ARP N370340.419 W1221415.345 42788.5
DH3879 P224 SIBLEYVOLCCN2005 CORS ARP N375150.014 W1221308.563 48670.9
DN7557 P217 LACROSSEDRCN2005 CORS ARP N370616.177 W1213902.224 54905.5
DI1085 P181 MILLERKNOXCN2005 CORS ARP N375452.349 W1222236.267 58235.8
NEAREST NGS PUBLISHED CONTROL POINT
HT3215 MAYFIELD RADIO MAST N372643.643 W1220643.788 1318.3
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.
Did You Enter Rod Height In Feet Not Meters ?>Paul did you ?
say Paul, are you mixing meters and feet here? He's 1.84' out, not meters, so he is 0.57 meters out...
Yes, post the OPUS-RS report
Well, the residuals look good, so based on what you've posted, I'd be inclined to question the elevation value on the "supposed" benchmark that you ran to, and making sure that you're comparing apples to apples between the OPUS occupy point and the benchmark point.
The concern raised about an error in the originally issued Geoid 12 appears to be unrelated. The link posted indicates that the error was immediately corrected (by GEOID 12A) and in any case applies primarily to areas in the Gulf Coast. The OPUS data indicates that the point in question is in California where the error would not have applied.
When you say you "ran to the nearest benchmark", did you run it with a level from the opus point to the benchmark and back?
Yes, post the OPUS-RS report
Wasn't there a problem with OPUS and Hiper antennas awhile back? I don't recall the details, but I seem to remember that OPUS wasn't handling the Hiper antennas correctly.
Yes, post the OPUS-RS report
Hiper SR opus driving me crazy
using GPS back at turn of this century
Lots of level runs from disks along coast
GPS tie in using Locus + Promark 2 still and prior
Molding Hiper Srs into loops always about .06m off
recompute using Ashtech or GNSS solutions
Check in to what I am looking for. WTF
