LINK TO SLIDES:

ftp://ftp.ngs.noaa.gov/dist/whenning/GLRHM2010/

http://www.ngs.noaa.gov/PUBS_LIB/NGSRealTimeUserGuidelines.v1.0.pdf

LINK TO SINGLE BASE GUIDELINES:

WORKSHOP PLAN

BACKGROUND/DATUM EVOLUTION

REAL-TIME NETWORK GNSS POSITIONING – A CONFLUENCE OF TECHNOLOGY, A NEW INFRASTRUCTURE.

THE ROLE OF THE NGS IN RT GNSS POSITIONING

LOOKING AT THE RTN GUIDELINES: OPERATORS’ GUIDELINES

RTCM/INTERACTION – QUESTIONS, COMMENTS & CONCERNS.

-27

00

-25

00

-15

00

-10

00

-50

0 0

50

0

75

0

10

00

12

50

15

00

17

00

17

50

18

50

19

00

19

77

19

89

20

00

20

10

20

17

20

30

POSITIONING TECHNOLOGY-

A CARTOON GRAPH

TECHNOLOGY

YEAR

0.5' SAT IMAGERY,TERR. LASER SCANNING, 0.10' AERIAL MAPPING, NATIONAL NETWORKS

GNSS- GLONASS, GALILEO,

COMPASS/BEIDOU,INDOOR POSITIONING

GPS

RTK

RTN

TOTAL STATION

COMPASSTHEODOLITE

STICKS AND STRINGS

GIS

THE CHANGE FROM LABOR INTENSIVE TO TECHNOLOGY!

“Human knowledge is doubling every 10 years. The scientific knowledge produced between 1987 and 1997 is greater than that produced in all mankind’s history”.

Michio Kaku- renowned theoretical physicist

National Spatial Reference System(NSRS)

Consistent National Coordinate System

• Latitude

• Longitude

• Height

• Scale

• Gravity

• Orientation

and how these values change with time

GEODETIC DATUMS

HORIZONTAL2 D (Latitude and Longitude) (e.g. NAD 27, NAD 83 (1986))

VERTICAL1 D (Orthometric Height) (e.g. NGVD 29, NAVD 88, Local Tidal)

GEOMETRIC3 D (Latitude, Longitude and Ellipsoid Height)

Fixed and Stable - Coordinates seldom change (e.g. NAD 83 (1991), NAD 83 (2007))

also

4 D (Latitude, Longitude, Ellipsoid Height, Velocities) Coordinates change with time

(e.g. ITRF00, ITRF08)

CORS

PASSIVE MARKS

TEN-YEAR MILESTONES (2018)

1) NGS will compute a pole-to-equator, Alaska-to-Newfoundland geoid model,

preferably in conjunction with Mexico and Canada as well as other interested

governments, with an accuracy of 1 cm in as many locations as possible

2) NGS redefines the vertical datum based on GNSS and a gravimetric geoid

3) NGS redefines the national horizontal datum to remove disagreements with the

ITRF

GRAVITY FOR ORTHOMETRIC HEIGHTS (“ELEVATIONS”)

NO GRAVITY = NO HEIGHTSKNOW GRAVITY = KNOW HEIGHTS

http://www.ngs.noaa.gov/GRAV-D/pubs/GRAV-D_v2007_12_19.pdf

GRAV-D PROGRAMNEW VERTICAL DATUM AROUND 2018

-

DATUM=•SURFACE•ORIENTATION•ORIGIN•SCALE+ GRAVITY

Z

YX

-Z

-X

-Y

Zero

Meridian

Mean Equatorial Plane

GNSS POSITIONS ARE ECEF,

XYZ

11

THE GEOID AND TWO ELLIPSOIDS

NATIONAL OCEAN

SERVICE

GRS80≈WGS84CLARKE 1866

GEOID

Earth

Mass

Center

Approximately

236 meters

Earth-Centered-Earth-Fixed CoordinatesZ Axis

X Axis

Y Axis

(X,Y,Z)

Earth’s

Surface

Zero

Meridian

Mean Equatorial Plane

P

Origin

(0,0,0)

Center of Mass

X

Y

Z

Conventional

Terrestrial

Pole

GPS - Derived Ellipsoid Heights

Z Axis

X Axis

Y Axis

(X,Y,Z) = P (,,h)

h

Earth’s

Surface

Zero

Meridian

Mean Equatorial Plane

Reference Ellipsoid

P

Simplified Concept of ITRF 00 vs. NAD 83

NAD 83

Origin

ITRF 00 ORIGIN

(WGS 84 IS WITHIN

A COUPLE OF

CENTIMETERS IN

REALIZATION)

Earth’s

Surface

h83

h00

Identically shaped ellipsoids (GRS-80)

a = 6,378,137.000 meters (semi-major axis)

1/f = 298.25722210088 (flattening)

NAD83(86) to ITRF00 Ellipsoid Heights (meters)

USE USGG09

USE GEOID09

Heights Matter!

HARD TO ACCESS PASSIVE MONUMENTS

Disturbed Geodetic Control

Coordinates/Elevations

Questionable!

Destroyed Geodetic Control

No Coordinates/Elevation

Monumented Points

Deterioration

MISSING MARKS- TYPICAL EXAMPLE

Real Time for Agriculture

DUAL FREQUENCY CARRIER RTK –

NOT CODE

AGRICULTURE

DEM - Digital Elevation Model

Flood Zone Boundary

Red –Original

Blue – Improved with LIDAR

LIDAR and Derivative Products CONTROLLED FROM RTN(Light Detection and Ranging )

Height Modernization

Slide by Gary Thompson, NC Geodetic Survey

PROACTIVE

FLOOD MODELING

REMOTE SENSING/MAPPING – LIDAR(currently around an order of magnitude

less precise than classical RTK, ie. .1 – .4 m)

NAVIGATION TO/FROM PORTS-

ELLIPSOID HEIGHTS

RT DEFORMATION MONITORING-BRIDGES, BUILDINGS, DAMS, LEVEES,

SUPPORT WALLS

TRIPLE DIFFERENCING & KALMAN FILTERING

SOME GIS DATA LAYERS BENEFITTING FROM HIGH ACCURACY POSITIONING

• INFRASTRUCTURE/ASSET MANAGEMENT- ALL UNDERGROUND UTILITIES, AS BUILTS: WATER, SEWER, STORM DRAIN, ETC.

• ENVIRONMENTAL

• ROAD PROFILES/EMERGENCY MANAGEMENT

• PHOTO ID POINTS – LIDAR, AERIAL MAPPING

• CADASTRE – PLATS, BOUNDARY SURVEYS, “BOUNDARY” MARKERS, PARCEL AREAS

• SIGNAGE – URBAN AREAS

• REFINING ZONING LINES – CRITICAL ZONING LINES, DISTANCES, IMPERVIOUS AREAS, BUFFER LINES

• SHORE LINE/ WATER LEVEL – DEFINES BOUNDARIES,

FLOOD ZONES-FEMA

• GEODETIC CONTROL

• DTM - CONTOURS

ACCOMPLISHING ACCURATE DATA COLLECTION95% CONFIDENCE

• SBAS- 3 M H, 6 M V

• COMMERCIAL DGPS – FEW DM, $$

• USCG BEACON – METER+

• CLASSICAL SURVEYING – 2-4 CM, LABOR/TIME INTENSIVE, $$$

• USER BASE RTK – 2-4 CM H, 3-5 CM V

• RTN – 3-4 CM H, 5-7 CM V

• AERIAL MAPPING - .15 M H, .25 M V, $$$

• SATELLITE IMAGERY – 0.5 METER H RESOLUTION, 3 M LOCATION, $$$

• LOW ALTITUDE AERIAL IMAGERY – 2-4 CM h, 3-5 CM V, $$

• TERRESTRIAL LASER SCANNING – PROJECT SITES ONLY, 0.015 H, 0.02 V

Has anyone ever asked you to provide data lessaccurate than before?

ACADEMIC/SCIENTIFIC

SPATIAL REFERENCE CENTERS

VARIOUS DOTS

COUNTY

CITY

GEODETIC SURVEYS (NC, SC)

MANUFACTURERS

VENDOR NETWORKS

AGRICULTURE

MA & PA NETWORKS

EXAMPLES OF RTN ADMINISTRATORS IN THE USA

RAPIDLY

GROWING

EXAMPLE: GNSS DERIVED HEIGHTS

• NOS-NGS 58/59 ELLIPSOID/ ORTHO GUIDELINES-0.05 m TO NSRS, 0.02 m LOCAL

• OPUS-S > 4 HRS = 0.02 M (h), 0.06 (H)

• CORS- SAME AS OPUS CORS- SAME AS OPUS

• OPUS-RS 15 MINUTES =0.06 m

• DGPS – 15 SECONDS, 0.5 TO 2 m

• SINGLE BASE RTK- “IT DEPENDS!” 5 SECONDS (better than 0.03 m expected)

• RTN – “IT DEPENDS!” 5 SECONDS ( better than 0.04 m expected)

CHANGE IN ACCESSING THE NSRS BY PASSIVE TO ACTIVE MONUMENTATION AND FROM STATIC TO REAL TIME

RT PROCESSING IN YOUR ROVER

SOME RT FIELD CONSIDERATIONS- Multipath- Position Dilution of Precision (PDOP)- Baseline Root Mean Square (RMS)- Number of satellites- Elevation mask (or cut-off angle)- Base accuracy- datum level, local level- Base security- Redundancy, redundancy, redundancy- Part(s) Per Million Error (ppm) – iono, tropo models, orbit errors- Space weather- sunspot numbers, solar maximum- Geoid quality- Site calibrations (a.k.a. Localizations)- Bubble adjustment- Latency, update rate- Fixed and float solutions- Accuracy versus Precision- Signal to Noise Ratio (S/N or C/N0)- Float and Fixed Solutions- Carrier phase- Code phase- VHF/UHF radio communication- CDMA/SIM/Cellular TCP/IP communication-WGS 84 versus NAD 83, or other local datums- GPS, GLONASS, Galileo, Compass Constellations

THE THREE BASE STATION OPTIONS FOR RT

•INTERNET DATA VIA CELL TECHNOLOGY

•SOFTWARE/FIRMWARE ALGORITHMS

•GNSS HARDWARE

•SATELLITE CONSTELLATIONS

•SATELLITE CODES/FREQUENCIES

THE USE OF RTK- A CONFLUENCE OF TECHNOLOGY

GLONASS ENHANCEMENTSEUROPEAN UNION - GALILEO

CHINA – COMPASS/BEIDOU

STANDALONE POSITIONING: BY 2019?

GPS:• L2C• L5 CARRIER• New Code on L5• L1C

1-3 m

BETTER RESISTANCE

TO INTERFERENCE

FASTER AMBIGUITY

RESOLUTION

AUGMENTED CODE

APPLICATIONS

10-15 cm???

2000 ERROR BUDGET (POST S/A)

= 115 SATELLITES?1st BLOCK II-F SCHEDULED FOR MAY

2010

20 GLN IN ORBIT (18 OPERATIONAL)

NEW SIGNALS BOTTOM LINE:L5 (1176.45 MHz) , L2C (NEW CIVIL CODE)

• More robust• Stronger signal - lower carrier-to-noise-density ratio (c/n0) values than would otherwise be possible. • Better signal tracking & differentiation especially at lower elevations means better code positioning under canopy (the better cross-correlation performance means that the reception of weak gps signals is much less affected by simultaneously received strong gps signals, which can be of significant advantage in difficult signal reception conditions.) •Code iono error mitigation using L1 C/A, L2C, & P2 differencing (eventually L5 on block IIF & L1C on block III)•Longer baseline solutions•Faster ambiguity resolution•improved QA/QC with additional frequency checking•Faster, more accurate NAV updates• L2C has similar multipath characteristics as L1 C/A

RTK vs. RTN

RTK

RTNPlus:

Easy alignment to the NSRSNo ppm (1ST ORDER) ERROR

Extended rangeHomogeneous DataEasy datum updates

Cell technology

-Half the equipment or double the production-No monument reconnaissance/recovery- No set/break down time-No base baby sitting

NGS GOALS FOR RTN’s

• All real-time positioning services available in the U.S. provide coordinates that are consistent with the National Spatial Reference System, and hence, with each other

• User equipment can operate with services from different RTN’s to the greatest extent possible

• Reference stations contained in each RTN meet prescribed criteria in terms of stability and data quality

• Best methods for RTN users may be advanced

36

REAL-TIME ACTIVITIES AT THE NGS

I. OPERATE AN NTRIP CASTER. (Fed. Owned/operated – currently 8. RTCM 2.3 & 3.0, From Foundation CORS. NO CORRECTORS)

II.DEVELOP AND PUBLISH GUIDELINES DESCRIBING BEST PRACTICES IN RTK & RTN .(RTK Users draft, RTN Operators draft, etc.)

III.PARTICIPATE IN MEETINGS, FORUMS, WORKSHOPS, ETC., CONCERNING REAL-TIME NETWORKS. SEEK LEADERSHIP ROLES.(FIG, FGCS, ESRI, ACSM, RTCM, etc.)

IV.RESEARCH PHENOMENA AFFECTING ACCURATE REAL-TIME POSITIONING. (Orbits, refraction, multipath, antenna calibration, geoid separations, gravity, crustal motion, etc.)

PASSIVE MONUMENTS ACTIVE STATIONS

STATIC REAL TIME

NGS 58/59 GUIDELINES RTK- SINGLE BASELINE

FGDC ACCURACY STDS. NGS CLASSICAL USER MANUFACTURERS SOFTWARE GUIDELINES

NETWORKSNGS RTN GUIDELINES-

INTERNAL DRAFT

LABOR/COST/GEAR

200+ WORLDWIDE

80+ USA

VRS/MAC/FKP

POSITIONING

NGS GNSS POSITIONING GUIDELINES

NGS AND RTN- PLAYING CATCH UP WITH THE NOW CROWD

RTN WILL BE THE PRIMARY ACCESS TO THE NSRS

THE TWO DIRECTIONS OF REAL-TIME NETWORK POSITIONING

I. TOP DOWN: Overall Administrator’s viewpoint-Alignment to the NSRS, coordinates, adjustments, Network spacing, Site requirements, Communication issues, Personnel, Cost/Benefit analysis, $$$$, Partners

II. USER UP: Best methods- Field techniques, GNSS knowledge, Knowing datum requirements, Knowing accuracy requirements, Calibrations, Applications, Data management

60 INDIVIDUALS-NGS, DOT, SRC,

GEO.SURVEYS, GNSS MFTRS.

INTERNAL PEER REVIEW-EARLY 2010

RELEASED FOR PUBLIC COMMENT-

MAY 2010 (?)

WILL NOT SPECIFY OR DEFINE A STANDARD, BUT

WILL HELP ADMINISTRATORS AND

USERS TO BE AWARE OF ALL THE ISSUES INVOLVED WITH

THIS NEW TECHNOLOGY

RATIONALE:• 10 YEAR PLAN – In support of RT access to NSRS,

write new guidelines

• STRATEGIC PLAN: Develop guidelines for both the administration and use of real-time GNSS networks and especially for ensuring that these networks are

compatible with the NSRS. = NGS “Blessing”

•No available comprehensive document on RTN positioning. How can we have confidence in RT data if no recommendations or best methods are sanctioned?

• This will be the preferred method to access the NSRS for agriculture, machine control, GIS, surveying,

engineering, navigation (sea, land, maybe augmenting air approaches)

≥200 RTN WORLDWIDE

≥80 RTN USA

≥35 DOT

ACADEMIC/SCIENTIFIC

SPATIAL REFERENCE CENTERS

VARIOUS DOTS

COUNTY

CITY

GEODETIC SURVEYS (NC, SC)

MANUFACTURERS

VENDOR NETWORKS

AGRICULTURE

MA & PA NETWORKS

USING RTN

“Washington Maintaining Lock Crossing the Delaware River”

1850

SOME RTN ADMINISTRATOR CONCERNS

• $$$$$$$$$$$$$$$/ Business Model• Seasonal movement• Integrity Monitoring• Spacing• Communication• OPUS vs. CORS RTN adjustment• Upgrade? GNSS?• Velocity models for RTN stations (not CORS)• Velocity for CORS-HTDP, monthly CORS or

wait till tolerance exceeded?• Orthos?• Datum/adjustment• Weather sensors ($2K) for tropo (humidity)

modeling (not upper atmosphere)

DIFFERENT RTN METHODOLOGIES

NON-PHYSICAL REFERENCE STATION MASTER-AUXILLIARY CONCEPT(DUPLEX COMMUNICATION)

DIFFERENT RTN METHODOLOGIES

CLOSEST BASE(NO INTERPOLATED CORRECTIONS)

MANY RTN START THIS WAY

REVERSE PROCESSING

(graphic courtesy of Geodetics, Inc.)

FKP

INITIAL RTN FORMAT (EARLY 1990’S)MONOPLEX (NOT DUPLEX) COMMUNICATIONCORRECTION COEFFICIENTS FROM CLOSEST REFERENCE STATIONSPLANAR (GRID) CORRECTIONS

• ROBUST ELECTRICAL & INTERNET (No interference, add voltage regulator, lightening rod, latency)

• NOTHING WITHIN 3 M OR ABOVE 10°

• USE ANTENNA ADAPTER TO ATTACH ARP TO MARK

• ≤ 30 M LENGTH ATENNA TO RECEIVER USE LMR 400. LONGER USE LMR 600 OR ADD AN AMPLIFIER

• DO NOT USE A RADOME

• REMOVE ANTENNA MOUNT BASE FROM NEAR SURFACE EFFECTS (INSTALL DEEP BASED GROUND MOUNT OR STABLE BUILDING MOUNT)

GENERAL SITE RECOMMENDATIONS

BUILDING MOUNTS

FLUSH OUTRIGGER CORNER

• MASONRY BUILDINGS PREFERRED, NO FRAME BUILDINGS•BUILDINGS 5 YEARS OLD OR OLDER•STAINLESS STEEL MOUNT•BOLTED TO BUILDING•NO METAL FLASHING•BEWARE ELECTRICAL INTERFERENCE SOURCES SUCH AS TV, FM, MICROWAVE, RADAR, CELL BROADCASTS

GROUND MOUNTS

• PILLAR/DEEP BRACED QUAD LEG/TOWER

≤ $5K ≤ $10K

≤ $6K

PLANNING/ADMINISTRATION• Who pays? (cost/benefit, tax dollars, fee based, ear marks,

height mod)

• Partnerships (Academic, scientific, private, DOT, etc.)

• What will be provided? (e.g., data accuracy, formats)

• IT set up (central server, data archival, redundancy,

upgrade path, alarms, mirror sites, etc.)

• Evaluate communication integrity and data latency

(continuous)

• Reference Station Spacing. E.g, for a 200 Km x 200 Km area:46 stations at 30km spacing

39 stations at 40km spacing22 stations at 50km spacing

14 station s at 70km spacing

Difference could be a million dollars!

53

ALIGNING RTN TO THE NSRS-PURPOSE:

Promote consistency of RTN-generated coordinates with current realizations of both the North American Datum of 1983 (NAD 83) and the International Terrestrial Reference System (ITRS). Many RTN overlap with varying positional results

Note that NAD 83 is the official spatial reference system for geometric positioning in the United States.

OVERLAPPING RTN-NSRS?,

HOMOGENEOUS?, USES ALL GNSS GEAR?

ALLEN PRECISION- RTKNET

KEYSTONE - KEYNET

CARON EAST -

ACCESSING THE NSRS VIA ACTIVE STATIONS

combined

NTRIP & RTCM

NTRIP

Federal Agency for Cartography and Geodesy (BKG)

Ntrip is a generic, stateless protocol based on the Hypertext Transfer

Protocol HTTP/1.1 and is enhanced to GNSS data streams via TCP/IP.

Networked Transport of RTCM via Internet Protocol (NTRIP) –Application and Benefit in Modern Surveying Systems

Elmar LENZ, Trimble GmbH Germany

FIG Working Week 2004 Athens, Greece, May 22-27, 2004

NtripServer is software running on a conventional PC that sends

correction data from a GNSS receiver (COM-port) to a third installation (from NtripSource to NtripCaster)

The NtripCaster is in general a HTTP server and acts, as already described, as a

broadcaster integrated between the data sources (NtripServer) and the data receiver

(the NtripClients).

NtripClient resides on the field rover data collector

RADIO TECHNICAL COMMISSION FOR MARITIME SERVICES

SPECIAL COMMITTEE ON DIFFERENTIAL GNSS

POSITIONING= RTCM SC-104• INTERNATIONAL STANDARDS BY ORGANIZATIONS- non-profit scientific, professional and educational, governmental and non-governmental

•RTCM format is OPEN SOURCE, GENERIC

•RECOMMENDED STANDARDS FOR DIFFERENTIAL GNSS POSITIONING

•ALL MAJOR RT GNSS GEAR CAN USE THIS FORMAT

•IN USA, MEMBERS INCLUDE: FCC, USCG, NGS, MAJOR GNSS MANUFACTURERS

•NTRIP STANDARDS (An application-level protocol that supports streaming (GNSS) data over the Internet)

RTCM SC104- V. 3.X

ADDS MESSAGE TYPES FOR RTNS

DESIGNED FOR GLONASS, GALILEO, L2C, L5

50% LESS BANDWIDTH THAN V 2.3, BUT MORE MESSAGE TYPES

SIMPLIFIES NETWORK SOFTWARE TASKS (ONLY MUST RESOLVE AMBIGUITIES)

STANDARDIZES RTN INFORMATION AND MODELS

RTCM Paper 014-2007-SC104-462

IMPROVING GNSS ROVER PERFORMANCE WITH RESIDUAL MESSAGES

• Because there are an increasing number of mixed GPS/GLONASS networks and sparse GLONASS networks with reduced GLONASS correction quality….

• There will be very heterogeneous GNSS networks in the future (L5, Galileo, L2C)

• Therefore, a method is required to transfer the quality of corrections to the rover - addressing various factors

• Predicted error statistics can help to improve positioning by: Better measurement weighting, Optimum combination of L1/L2 measurements

• Helps to improve: Positioning accuracy, Ambiguity fixing

Positioning improved by up to a factor of 2

Initialization time reduced by 30%

Standard Solution (RMS:21 mm)

Optimized Solution (RMS:13 mm)

RTCM Paper 014-2007-SC104-462

POSITIONING ERROR COMPARISON –HEIGHT ERROR

NGS WEB PAGES – CURRENTLY TEST/BETA

USCG

86 TOTAL -38 INLAND (DOT)

DEVELOPING COOPERATIVE PARTNERS

ADDITIONAL RT STREAM APPLICATIONS

• Monitor distribution of water vapor in the atmosphere

• Monitor distribution of free

electrons in the ionosphere

• Detect interference to GPS signals

• Detect rapid ground motion associated with

earthquakes and volcanic eruptions to alert public to hazards such as damage to critical structures (dams, bridges, etc.) or an impending lava flow or tsunami

• Enable OPUS (and similar utilities) to process GNSS data immediately after these data are observed

69

PBO STATIONS

BINEX, RTCM 2.4, RTCM 3.0

0.6 to 2.0 seconds latency

SERVER IN BOULDER, CO

147 RT STATIONS +/-

http://pboweb.unavco.org/?pageid=107

http://www.ntrip.org/155 STREAMS TO

http://www.igs-ip.net/home

Participating agencies Bundesamt fuer Kartographie und Geodaesie, Germany, (BKG)Crustal Dynamics Data Information System, NASA, USA, (CDDIS)ESA's European Space Operations Centre (ESOC)Florida Internalional University, USA, (FIU)GeoForschungZentrum Potsdam, Germany (GFZ)Geosciences Australia (GA)Jet Propulsion Laboratory (JPL)Korean Astronomy and Space Science Institute, (KASI)

National Geodetic Survey, USA (NGS)National Geographic Information Institute, Korea (NGII)Natural Resources Canada (NRCan)Polytechnic University of Catalonia, Spain, (UPC)

TU Delft, NL (DUT)TU Vienna, Austria (TU Wien)University Corporation for Atmospheric Research, USA (UCAR)

University of Southern Mississippi, USA, (USM)

U.S. Naval Laboratory, USA, (NRL)

U.S Naval Observatory, USA (USNO)

REAL-TIME CHOICESBIG PICTURE ISSUES

• PASSIVE / ACTIVE – WHAT IS „TRUTH‟?

• GEOID + ELLIPSOID / LOCALIZE –QUALITY OF GEOID MODELS LOCALLY. ORTHOMETRIC HEIGHTS ON CORS?

• GRID / GROUND –LOW DISTORTION PROJECTIONS- SHOULD NGS PLAY?

• ACCURACY / PRECISION- IMPORTANCE OF METADATA

• SINGLE SHOT / REDUNDANCY

• RTK / RTN

• NATIONAL DATUMS / LOCAL DATUMS / ADJUSTMENTS-DIFFERENT WAYS RTN GET THEIR COORDINATES-

VARIOUS OPUS, OPUS-DB, CORS ADJUSTED, PASSIVE MARKS.

VELOCITIES - NEW DATUMS, “4 -D” POSITIONS

• GNSS / GPS

#1 Include a subnetwork of the RTN into the NGS CORS network. This would be three stations If RTN has less than 30 stations, 10% of RTN with greater than 30 stations.

#2 Align all RTN reference stations coordinates to the CORS network at 2-cm horizontal and 4-cm vertical

#3 For each reference station in the RTN, use the a version of Online Positioning User Service (OPUS) at http://www.ngs.noaa.gov/OPUS/ to test for the continued consistency of its adopted positional coordinatesand velocity on a daily basis, and revise the station’s adopted coordinates and/or velocity if the tests reveal a need to do so. OPUS-PROJECTS looks promising

#4 NGS encourages each RTN to provide access to users of all major GNSS manufacturers’ equipment

ALIGNING RTN TO THE NSRS:

#5 NGS promotes the use of RTCM format data via NTRIP communication protocol application.

“OnCors”

Potential OnCORS network.

Green dots represent NOAA-sponsored stations from which GNSS data streams are

currently available.

Yellow dots represent NDGPS stations that easily can be upgraded to provide real-time

GNSS data streams.

Red dots represent NDGPS stations whose GPS sensors must be replaced for them to

provide real-time GNSS data streams.

-16 STREAMS60+ CURRENT REGISTRANTS

“FOUNDATION” CORS CONCEPT AT NOMINAL 400 KM SPACING

RTCM 3.X

“OPUS-LIKE” GENERATED GRAPHIC OF RTN STATIONS- SIMILAR TO CORS 60-DAY PLOT

ALL CORS FIXED

ALL CORS WEIGHTED

OPUS (Average of 10 days of 24 hour data sets)

OPUS + HARN

BEST FIT TO ONE MASTER STATION

THE NGS RECOMMENDATION: Process at least 10 days of GPS data from all RTN stations using a simultaneous network adjustment while “constraining” several CORS coordinates with weights of 1 cm in each horizontal dimension and 2 cm in the vertical dimension.

REFERENCE STATION COORDINATE DERIVATION:

79

SUGGESTIONS FOR DETERMINING VELOCITIES FOR RTN STATIONS

• Use the HTDP (Horizontal Time-Dependent Positioning) software to predict velocities for new RTN stations. (The predicted vertical velocity will be zero.)

• After 3 years, use GPS data from the RTN station to produce a time series of the station’s coordinates, then use this time series to estimate a velocity for the RTN station.

Implementing Recommendation 2-GOLDSTONE Example

NGS Adopted values

ITRF 2000 epoch 1997.0

RTN Operator values

ITRF 2000 epoch 2008.0

X -2353614.3671m -2353614.5442 m

Y -4641385.407 m -4641385.3421 m

Z 3676976.468 m 3676976.4119 m

VX 0.0161 m/yr 0.0161 m/yr

VY -0.0059 m/yr -0.0059 m/yr

VZ 0.0051 m/yr 0.0051 m/yr

NAD 83

ITRF 2000

SILVER SPRING, MD

NAD 83 VELOCITIES

(GOLD)

ITRF 2000VELOCITIES

(BLUE)

SANTA CRUZ, CA

Movement from passive monumentation towards Active monumentation and from

traditional positioning and traversing towards RT positioning via GNSS RTN is a movement

from 3-D positioning towards 4-D Positioning in most of the conterminous USA.

This necessitates the recordation of metadata: source of coordinates, datum, datum epoch, alignment to the NSRS, grid/ground, date of

field survey, antennas, GNSS gear, etc.

ORTHO HEIGHTS - LOCALIZE OR NOT?• PASSIVE MARKS ARE A SNAP SHOT OF WHEN THEY

WERE LEVELED OR DERIVED FROM GPS

• IF YOU BUILD FROM A MONUMENTED BM AND THE DESIGN WAS DONE REFERENCED TO IT, IT IS “THE TRUTH”, UNLESS IN GROSS ERROR.

• CALIBRATIONS ARE A GOOD WAY TO NOT ONLY LOCK TO THE SURROUNDING PASSIVE MARKS, BUT ALSO TO EVALUATE HOW THE CONTROL FITS TOGETHER.

• HOW GOOD IS THE NGS HYBRID GEOID MODEL IN YOUR AREA? (SIDE NOTE: GEOID 09 IS THE CURRENT MODEL USED BY OPUS)

ELLIPSOID, GEOID & ORTHO HEIGHTS

H88 = h83 – N03

NAD 83 (HARN) USE GEOID O3

NAD 83 (CORS 96) USE GEOID 09

ITRF USE SCIENTIFIC GEOID (USGG)

Various NGS Geoid models• GEOID90

• GEOID93

• GEOID96

• GEOID99

• GEOID03

• GEOID09

• Earliest model – gravimetric only

• Another early gravimetric geoid

• First hybrid geoid – CONUS only

• Underlain by G96SSS gravimetric model

• Accuracy ~ 11.6 cm (95%)

• Still fairly heavily used - CONUS

• Underlain by G99SSS gravimetric model

• Accuracy ~ 9.2 cm (95%)

• Models tie to NAD 83 everywhere – hybrid in CONUS

• Underlain by the USGG2003 gravimetric model

• Accuracy ~ 4.8 cm (95%)

• Underlain by the USGG2009 gravimetric model

• Will tie to NAD 83 and NAVD 88/PRVD02/etc.

• Accuracy ~ 2 cm (statistics not yet available)

NGS Data Sheet - GEOID03

Published NAVD88 to GPS Derived HT2268 DESIGNATION - S 1320

HT2268 PID - HT2268

HT2268 STATE/COUNTY- CA/SAN FRANCISCO

HT2268 USGS QUAD - SAN FRANCISCO NORTH (1975)

HT2268

HT2268 *CURRENT SURVEY CONTROL

HT2268 ___________________________________________________________________

HT2268* NAD 83(1992)- 37 45 25.30727(N) 122 28 36.34687(W) ADJUSTED

HT2268* NAVD 88 - 102.431 (meters) 336.06 (feet) ADJUSTED

HT2268 ___________________________________________________________________

HT2268 EPOCH DATE - 1997.30

HT2268 X - -2,711,121.437 (meters) COMP

HT2268 Y - -4,259,419.310 (meters) COMP

HT2268 Z - 3,884,200.262 (meters) COMP

HT2268 LAPLACE CORR- 5.53 (seconds) DEFLEC03

HT2268 ELLIP HEIGHT- 69.78 (meters) GPS OBS

HT2268 GEOID HEIGHT- -32.60 (meters) GEOID03

HT2268 DYNAMIC HT - 102.363 (meters) 335.84 (feet) COMP

HT2268 MODELED GRAV- 979,964.0 (mgal) NAVD 88

HT2268

HT2268 HORZ ORDER - FIRST

HT2268 VERT ORDER - FIRST CLASS I

HT2268 ELLP ORDER - FOURTH CLASS I

HT2268

H =

102.431 =

102.431 102.38

69.78 - (-32.60)

- Nh

GEOID96 = 0.17 m

GEOID99 = 0.11 m

GEOID03 = 0.05 m

GEOID09 = 0.017m 102.431 102.414

69.764- (-32.65)

INTERPOLATIVE DILUTION OF PRECISION (IDOP)

OPUS-RS accuracy is dictated by CORS

geometry and distances

IDOP - local CORS geometry relative to

rover location

BEST IDOP = 1

√ N

RMSD – CORS distances* recent paper in “GPS Solutions” –

Accuracy Assessment of the NGS’s OPUS-RS UtilityBy C. Schwarz, R. Snay, & T. Soler

WHEN SHOULD RTN COORDINATES BE UPDATED?

VELOCITIES SHOULD BE KEPT IN THE METADATA

VERTICAL MOVEMENT IS MORE DYNAMIC AND NOT CURRENTLY MODELED (E.G.HTDP)

RTN ANTENNA MOVEMENT

2002 2003 2004 2005 2006 2007 2008

2002 2003 2004 2005 2006 2007 2008

Position Time Series (long-term)

2002 2003 2004 2005 2006 2007 2008

earthquake

seasonal variation

POSSIBLE REASONS FOR CYCLICAL MOVEMENT

FLUID WITHDRAWAL/INFUSION

OCEAN LOADING

ATMOSPHERIC LOADING

RECEIVERS

PROCESSING

IONO MODELING

VOLCANIC “BREATHING”

INTERMITTENT ELECTRICAL INTERFERENCE

SNOW

EXAMPLE OF WHY RTN REFERENCE STATIONS SHOULD BE MONITORED

≈ 6 MM / YEARENGLISH TURN CORS

SUBSIDENCE

SUNSPOT CYCLE

• Sunspots follow a regular 11 year cycle

• We are just past the low point of the current cycle

• Sunspots increase the radiation hitting the earth's upper atmosphere and produce an active and unstable ionosphere

http://www.swpc.noaa.gov/

RTN DECISION MAKING• GNSS BRANDS ARE INSIGNIFICANT IN THE

SELECTION PROCESS

• OPT FOR THE MOST UPGRADABLE GNSS HARDWARE

• PLAN FOR THE WIDEST EFFECTIVE REFERENCE STATION SPACING

• VENDOR SUPPORT IS CRITICAL

• RTN COMMUNICATION IS KING AND MUST BE BLESSED THROUGH I.T. (LATENCIES, INTEGRITY, REDUNDANT SYSTEMS, FIRE WALL ISSUES, BAND WIDTH, ETC.)

• PICK THE BEST BUSINESS MODEL FOR YOUR NEEDS

• TALK TO OTHERS WHO HAVE PAID THEIR DUES

INDIANA RTN

• PRIVATE VRS (MULTISTATE)

• INDOT CORS

INDIANA RTN