-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
1/41
1
INTRODUCTION TO GPS
OSU GPS WORKSHOPFebruary 10, 2011
Michael Olsen, PhD -Assistant ProfessorMark L. Armstrong, PLS -NGS Oregon Advisor
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
2/41
2
GPS survey goal, plan, and schedule
CORS (active marks)
National Spatial Reference System
OPUS-S, OPUS-RS, OPUS-DB (publishing)
Using passive marks
Mission Planning
PART IV - GPS Survey Planning
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
3/41
3
GPS survey planning
What is the survey goal? Single point; small network; large networkProject specifications; standards (FGDC); accuracy requiredHorizontal and vertical datumGeoid model choice; hybrid or pure gravimetric
Survey Style; static; fast static; RTK; RTNWhat will control the survey?
CORS; HARN; other passive marks or a combination?What software will be used?
Then make a mission plan and schedule
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
4/41
4
Standards for Geodetic Networks Federal Geographic Data Committee standards, Part 2
FGDC-STD-007.2-1998Maintained by the National Geodetic Survey
Sponsored by: Federal Geodetic Control Subcommittee
GPS survey planning cont.
http://www.fgdc.gov/standards/projects/FGDC-standards-projects/accuracy/part2/index_html
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
5/41
5
Standards for Geodetic Networks Objectives
To provide consistency in reporting the accuracyof point geospatial data collected by differentactivities (e.g., geodetic surveying, topographicmapping, bathymetric mapping, facilitiesmanagement mapping, cadastral surveying, etc.)and develop a FGDC document with a singlemethodology that defines how to report thepositional accuracy for all point geospatial datacollected, produced, or disseminated by the
Federal government and the Nation.
GPS survey planning cont.
http://www.fgdc.gov/standards/projects/FGDC-standards-projects/accuracy/part2/index_html
http://www.fgdc.gov/standards/projects/FGDC-standards-projects/accuracy/part2/index_htmlhttp://www.fgdc.gov/standards/projects/FGDC-standards-projects/accuracy/part2/index_htmlhttp://www.fgdc.gov/standards/projects/FGDC-standards-projects/accuracy/part2/index_htmlhttp://www.fgdc.gov/standards/projects/FGDC-standards-projects/accuracy/part2/index_htmlhttp://www.fgdc.gov/standards/projects/FGDC-standards-projects/accuracy/part2/index_htmlhttp://www.fgdc.gov/standards/projects/FGDC-standards-projects/accuracy/part2/index_htmlhttp://www.fgdc.gov/standards/projects/FGDC-standards-projects/accuracy/part2/index_html -
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
6/41
6
Standards for Geodetic Networks Scope
Part 2 applies to accuracy reporting for geodeticnetworks. Geodetic control surveys are usuallyperformed to establish a basic control network(framework) from which supplemental surveyingand mapping work, covered in other parts of thisdocument, is performed. Geodetic networksurveys are distinguished by use of redundant,interconnected, permanently monumentedcontrol points that comprise the framework for
the National Spatial Reference System (NSRS) orare often incorporated into the NSRS.
GPS survey planning cont.
http://www.fgdc.gov/standards/projects/FGDC-standards-projects/accuracy/part2/index_html
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
7/417
Standards for Geodetic NetworksTable 2.1 -- Accuracy Standards
Horizontal, Ellipsoid Height, andOrthometric Height---------------------------------------------Accuracy 95-PercentClassification Confidence---------------------------------------------Less Than or Equal to:
1-Millimeter 0.001 meters2-Millimeter 0.002 "5-Millimeter 0.005 "1-Centimeter 0.010 "2-Centimeter 0.020 "5-Centimeter 0.050 "1-Decimeter 0.100 "2-Decimeter 0.200 "5-Decimeter 0.500 "1-Meter 1.000 "2-Meter 2.000 "5-Meter 5.000 "10-Meter 10.000 "
GPS survey planning cont.
http://www.fgdc.gov/standards/projects/FGDC-standards-projects/accuracy/part2/index_html
When control points ina survey are
classified, they havebeen verified as beingconsistent withall other points in thenetwork, not merelythose within that
particular survey.
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
8/418
Standards for Geodetic NetworksSection 2.2.2 -- Accuracy Determination Four Steps:
l. The survey measurements, field records, sketches, and other documentationare examined to verify compliance with the specifications for the intendedaccuracy of the survey. This examination may lead to a modification of theintended accuracy.2. Results of a minimally constrained, least squares adjustment of the surveymeasurements are examined to ensure correct weighting of the observationsand freedom from blunders.
3. Local and network accuracy measures computed by random errorpropagation determine the provisional accuracy. In contrast to a constrainedadjustment where coordinates are obtained by holding fixed the datum valuesof the existing network control, accuracy measures are computed by weightingdatum values in accordance with the network accuracies of the existingnetwork control.4. The survey accuracy is checked by comparing minimally constrainedadjustment results against established control. The result must meet a 95percent confidence level. This comparison takes into account the networkaccuracy of the existing control, as well as systematic effects such as crustalmotion or datum distortion. If the comparison fails, then both the survey andnetwork measurements must be scrutinized to determine the source of theproblem.
GPS survey planning cont.
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
9/419
Standards for Geodetic NetworksSection 2.2.3 -- Accuracy Reporting
When providing geodetic point coordinate data, a statement shouldbe provided that the data meets a particular accuracy standard forboth the local accuracyand the network accuracy.
For example, these geodetic control data meet the 2-centimeter localaccuracy standard for the horizontal coordinate values and the 5-centimeter local accuracy standard for the vertical coordinate values(heights) at the 95-percent confidence level. A similar statementshould be provided for these same data reporting the networkaccuracy.
GPS survey planning cont.
http://www.fgdc.gov/standards/projects/FGDC-standards-projects/accuracy/part2/index_html
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
10/4110
Horizontal and Vertical Datum
Horizontal DatumNAD 83(CORS96)Epoch 2002 [Current NSRS]
NAD 83(CORS96a)Epoch2010 [Mid 2011)
NAD 83(2007) [Most recent national adjustment of passive marks]
NAD 83(1998) [Oregon HARN]
Vertical DatumNAVD 88 [Current NSRS]
Geoid Models
Geoid09 [Current NSRS Hybrid Model]Geoid03 [Previous NSRS Hybrid Model]USGG2009 [Current NSRS Gravimetric Model]
GPS survey planning cont.
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
11/41
11
GPS (GNSS) Survey Styles
Static Survey > 20 minutes logging data at each station (typ. ~30-250km baselines)
Fast-Static Survey < 20 minutes logging data at each station (typ.
< 30km baselines)Both styles requires simultaneous observations for all stations in thecurrent session
Real-time kinematic Survey (RTK) Base station setuprequired with either radio or cell phone connection with all
rovers. Single base line differential correction performed
Real-time Network (RTN) Rovers communicate with RTNservers via cell phone data link. Network solution possible
GPS survey planning cont.
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
12/41
12
Continuous Operating Reference Stations (CORS)
GPS survey planning cont.
The CORS term istied to the NGSand refers toofficial nationalstations wheredata for thestation is archivedon NGS serversfor all users.
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
13/41
13
Oregon CORS and CGPS stations
GPS survey planning cont.
~31 CORS in Oregon
~139 CORS + CGPS-11 MYCS CORS
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
14/41
14
Other geodetic datum to constrain your networktoo
GPS survey planning cont.
HARN = High Accuracy Reference NetworkPassive marks available in the NGSIDB via datasheets.
In Oregon the latest horiz. HARN datum = NAD 83(1998)Older Oregon HARN were in 86 and 91
NAD 83(2007) = The most current national
adjustment of ~70,000 passive monuments.
others
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
15/41
15
In addition to choosing a datum you need tochoose a coordinate system made up of:
-map projection-geoid model
GPS survey planning cont.
Oregon Station Plane Coordinate System (2 zones)Oregon Coordinate Reference System (20 zones - new 2010)UTM Zones
others
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
16/41
16
GPS survey mission planning
Research available control
Set any new monuments for the network, and write
descriptions on how to get to and access the mark
Recon the site and make notes, sketches and visibilitydiagrams
Take digital photos of the monumentClose-up of the capHorizon shot of each setup on the monument
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
17/41
17
Make notes, sketches and writedescriptions at all monuments observed
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
18/41
18
Make a visibility diagram in the field
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
19/41
19
Shows azimuth andelevation of obstructionsto satellites. This will be
used in planning softwareto optimize theobservation time scheduleso that satellites will beavailable.
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
20/41
20
Observation data logging times based on the number ofsatellites available. These suggested times are still valid!
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
21/41
21
From Trimble GPS Planning tool shows #SV and PDOP
PDOP = Position Dilution of PrecisionPDOP values considered goodfor positioning aresmall, such as 3. Values greater than 7 are
consideredpoor.
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
22/41
22
Observation schedule shows: date; GPS day; sessionnumber; monument observed; observers name; observationlogging time (maybe same for each session or different)
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
23/41
23
GPS Planning Additional Reading
http://www.ngs.noaa.gov/PUBS_LIB/pub_GPS.shtml
Guidelines for Establishing GPS-derived Orthometric Heights(Standards: 2 cm and 5 cm) NOAA TM NOS NGS-59 Zilkoski, D.B.,Carlson, E.E., & Smith, C.L. Mar 26, 2008 PDF
NGS User Guidelines for Single Base Real Time GNSSPositioning v1.0 Henning, W.E. Jan 2010 PDF
Guidelines for Establishing GPS-Derived Ellipsoid Heights- NOAA TM NOS NGS-58 Zilkoski, D.B., D'Onofrio, J.D., Frakes,
S.J. Nov 1997 PDF orHTML
http://www.ngs.noaa.gov/PUBS_LIB/NGS592008069FINAL2.pdfhttp://www.ngs.noaa.gov/PUBS_LIB/NGSRealTimeUserGuidelines.v1.1.pdfhttp://www.ngs.noaa.gov/PUBS_LIB/NGS-58.pdfhttp://www.ngs.noaa.gov/PUBS_LIB/NGS-58.htmlhttp://www.ngs.noaa.gov/PUBS_LIB/NGS-58.htmlhttp://www.ngs.noaa.gov/PUBS_LIB/NGS-58.pdfhttp://www.ngs.noaa.gov/PUBS_LIB/NGSRealTimeUserGuidelines.v1.1.pdfhttp://www.ngs.noaa.gov/PUBS_LIB/NGS592008069FINAL2.pdf -
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
24/41
24
GPS Planning Free Software Tools
Trimble Setup Planning Software v. 2.9Download at:
Download the latest ephemeris files, and almanacs at:
http://www.trimble.com/planningsoftware_ts.asp
http://www.trimble.com/gpsdataresources.shtml
http://www.trimble.com/planningsoftware_ts.asphttp://www.trimble.com/gpsdataresources.shtmlhttp://www.trimble.com/gpsdataresources.shtmlhttp://www.trimble.com/gpsdataresources.shtmlhttp://www.trimble.com/planningsoftware_ts.asp -
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
25/41
25
GPS Planning Free Software Tools
Ashtech Web Mission Planning Tool
http://asp.ashtech.com/wmp/
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
26/41
26
Receiver
AntennaAntenna cablesRTK radio modem or cell phoneBatteriesBattery-to-receiver cablesBack-up batteries or cigarette light adaptorTripodsBipodsTribrachsTribrach adaptorsFlashlightMeasure tape or rodStation information
Observation log sheetsPaper and pencilTwo way radio or cell phoneObservation scheduleFlagging, paint, PK nails, hammerTraffic control equipment
Reference list
Emergency phonenumbers
names, addresses,telephone numbers of
private-property ownersrelevant to this
projectGate keys or combinationsMaps
If you plan to download andprocess data in the field, bringthe following materials.
Data CollectorLaptopMemory PC CARDs etc.
Equipment Checklist
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
27/41
27
Record your observationon every point.REMEMBER THAT THEANTENNA HEIGHT ISCRITICALLY IMPORTANT!!!
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
28/41
28
NGS OPUS Suite of Programs
The Online Positioning User Service
Your easy access to the NSRS through:
OPUS-S (static) >2 - 48 hours of data required OPUS-RS (rapid static) >15 min. 2 hours of data required
OPUS-DB (publish your observation to the OPUS database)- 4+ hours required for submission using OPUS-S
OPUS-Project (baseline processing and adjustment of networks)-Under development
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
29/41
29
How Good Can I Do With OPUS-S?
As a quality test,
2-hour data setsfrom more than200 CORS weresubmitted toOPUS-S and the
results comparedto the acceptedcoordinates.
Mean:
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
30/41
30
-0.04
-0.03
-0.02
-0.01
0.00
0.01
0.02
0.03
0.04
0.05
orthOffsetfrom24hr.Mean(m)
4 Hr/160
-0.04
-0.03
-0.02
-0.01
0.00
0.01
0.02
0.03
0.04
0.05
or
thOffsetfrom24
hr.Mean(m)
6 Hr/160
-0.03
-0.02
-0.01
0.00
0.01
0.02
0.03
0.04
0.05
hOffsetfrom24
hr.Mean(m) 8 Hr/160
-0.04
-0.03
-0.02
-0.01
0.00
0.01
0.02
0.03
0.04
0.05
orthOffsetfrom24
hr.Mean(m) 12 Hr/160
-0.04
-0.03
-0.02
-0.01
0.00
0.01
0.02
0.03
0.04
0.05
o
rthOffsetfrom24
hr.Mean(m) 24 Hrs/160
Time Scatter Plots (Horizontal)
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
31/41
31
More generally,Eckl et al.(NGS)preformed asimilar but
more extensivetest using thesame softwarebut outside
OPUS. Eckl et al., 2001, Accuracy of GPS-derived relative positions as a function of interstation distance andobserving-session duration, J. of Geod. 75, 633-640).
Their results provide a good rule of thumb foraccuracy versus session duration when using OPUS-Sand in many other applications.
How Good Can I Do With OPUS-S?
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
32/41
32
How Does OPUS-S Work?
OPUS-S processing highlights:
Everything is done in the International TerrestrialReference Frame (ITRF).
SV coordinates are held rigidly fixed.CORS coordinates are heavily constrained.
Neutral atmosphere (tropo) dry component modeled.Neutral atmosphere (tropo) wet component estimated.Double-differenced, ion-free carrier phase observable.Carrier phase ambiguities are fixed to their integer values where
possible; float ambiguities are estimated otherwise.
Individual baselines are processed and the results combinedgenerating mean coordinates and peak-to-peakuncertainties.
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
33/41
33
OPUS-S Uploads By Month
Valid as of 2010-03-30. Values before January, 2005 are approximate.
Shown here are
the monthlyupload countsto OPUS-S.
Submissions to
OPUS-Scomprise anon-trivialpercentage ofall hits on the
NGS web sites.
Average~15k/month
0
5000
10000
15000
20000
25000
30000
35000
40000
OPUS-S Uploads
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
34/41
34
The OPUS-RS Interface
With OPUS-RS, the beautiful simplicity remained. In fact the entry
form is the same as for OPUS-S.
The user provides:
Their email address.
An antenna type.The vertical offset to the ARP.15-minutes to 2-hours of GPS L1 + L2 data.
The user receives:
Coordinates accurate to a few centimeters.
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
35/41
35
The same interface is used except one clicks theUpload to RAPID-STATIC button instead.
The OPUS-RS Interfacehttp://www.ngs.noaa.gov/OPUS/
http://www.ngs.noaa.gov/OPUS/
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
36/41
36
How Good Can I Do With OPUS-RS?
http://www.ngs.noaa.gov/OPUSI/Plots/Gmap/OPUSRS_sigmap.shtml
The OPUS-RS Accuracy and Availability Tool.
http://www.ngs.noaa.gov/OPUSI/Plots/Gmap/OPUSRS_sigmap.shtml -
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
37/41
37
1 for each 0.2 degree grid.
Horizontal and vertical standarderrors for 15 minutes and1-hour length data.
Inverse Distance Weightingmethod to interpolate the sigmas.
Areas outside the color overlayare where there are less thanthree active CORS sites within250 km range. OPUS-RS willusually fail at these locations.
Automated Weekly update
Use updated CORS list andobservation data availability
Global coverage including non-USterritories.
How Good Can I Do With OPUS-RS?
http://www.ngs.noaa.gov/OPUSI/Plots/Gmap/OPUSRS_sigmap.shtml -
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
38/41
38
How Does OPUS-RS Work?
OPUS-RS selects three to nine best CORS based upon:
Having common satellite visibility with the userdata.
Having distances from the users site
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
39/41
39
How Does OPUS-RS Work?
In addition, users site must be no more than 50 km from the
(convex) polygon created by the selected CORS.
Again in this figure, the star represents the users site; thetriangles are CORS. Five CORS and their resulting polygon areshown in this example.
If the users site, the star, ismore than 50 km outsidethis polygon, alternateCORS will be considered.
If none can be found,the processing will abort.
Schwarz et al., Accuracy assessment of the National Geodetic
Survey's OPUS-RS utility, 2009, GPS Solutions, 13(2), 119-132.
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
40/41
40
OPUS-DB Interface
The view tab on the OPUShome page provides access tothe results stored in the data
base.
-
7/29/2019 2-10-11 Olsen Armstrong-Part4 GNSS Survey Planning
41/41
QUESTIONS ?