high accuracy nationwide differential global positioning system (ha-ndgps) jim arnold cgsic new...
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High AccuracyNationwide Differential
Global Positioning System(HA-NDGPS)
Jim ArnoldCGSIC New Orleans
July 2008
Problem and Program ObjectivesHA-NDGPS
• Examine ways to enable 3-D dynamic positioning at the centimeter level throughout the US,
• Coexist with existing infrastructure,• Minimize deployment costs.
Problem: Submeter resolution of vehicle position neededfor many advanced vehicle safety concepts.
Program Objective: Assess the implementation feasibility for improving the accuracy of the NDGPS service, usingexisting infrastructure, to meet the requirements of additionalapplications without decreasing availability and integrityand still meeting the needs of existing users.
GPS(13 meters)
Perspective on Accuracy Horizontal, Dynamic, 95%
NDGPS(1-2 meters)
HA-NDGPS(Dynamic)(.1 Meters)
HA-NDGPS(Static)(.01 Meters)
NDGPS• Nationwide network of GPS reference
stations• Provide real time code phase corrections for
diverse applications– Transportation– Agriculture– GIS
• Provides data for other users– NGS– UNAVCO– Etc.
Coverage
The Site
ATU
BUPG
Electronics
GSOS
HA-NDGPS Program Phases• Phase 1
Develop Modulator and Data Link ReceiversInterface System ModulesBroadcast Characterization and Optimization Single Site Concept Demonstration (Hagerstown, MD)
• Phase 2Pre-Broadcast Integrity AlgorithmMultiple Site/Baseline Concept Demonstration (Hawk Run, PA)Iono/Tropo PredictionApplication Development
Broadcast Site Configuration
TRANSMITTER
DIPLEXER
REFERENCE
STATION
DATA
FORMATTERMODULATOR
TRANSMITTERDGPS/NDGPS
HIGH ACCURACYDGPS
TO ANTENNA
OBSERVABLES
CORRECTIONS
Rack Mount PC
DSP/Analog Card
Data Formatter/Modulator Diplexor
Static Positioning at 50 kmActual Real-time Hydra plot of static
geodetic survey application performed at Dickerson, MD
47.8 km from reference station.
Reference Data Source – Hagerstown HA-NDGPS Broadcast
Long Range Single Baseline TestTangier Island HA-NDGPS Experiment
(250 km). Comparison of approximate “truth” geodetic coordinates of mail boatWith the real-time solution based upon the HA-NDGPS broadcast. Results are roughly 10-20 centimeters as expected at this great range.
Phase II• Hawk Run Installation Status
– Installed and Operating
• Testing– Report available
• http://www.navcen.uscg.gov/ndgps/HA-NDGPS.PhaseII.Report.July2004.four.pdf
• Application Development– Partnering with other agencies to develop applications– US Army Corps of Engineers
HA-NDGPS Coverage
Hagerstown, MD
Hawk Run, PA
Orbisonia , PA50 mile baselines
Multi-Station
“Accurate” SolutionNationwide RTK?
• What You Need:– Satellite Lock– Ground based system
broadcasting observables– Accurate Ephemeris– Accurate Clock data– Good ionosphere model– Good Troposphere model– Integrity Check– Multiple reference stations
at less than 200 mile baselines
• What You Get:– Initial .5 to 2 meter code
accuracy– Reduced search space for
integers– Very fast integer resolution
at long ranges
Code Differential Solution
500 100 150
50
0
100
150
Integer Resolution
500 100 150
50
0
100
150
Integer Resolution
500 100 150
50
0
100
150
Integer Resolution
500 100 150
50
0
100
150
Models - Total Electron Count
Wx Model-Derived Wet Signal Delay Over CONUS
Courtesy, Dr. Sunil Bisnath formally with USM, now at Harvard Smithsonian Astrophysical Observatory
Applications• Transportation
– Highway• Automated Road Construction• Intersection Collision Avoidance• Dynamic Mapping• Digital Highway Measurement Vehicle
– Railroad• Track Defect Monitoring
– Maritime• Under keel clearance
• USDA– Agriculture
• Precision Farming• Autonomous Farm Vehicles
– USFS• Logging boundaries• Infestation monitoring
• Interior– National Park Service
• Monitoring subsidence of critical monuments
• Real-time boundary marking
– Fish and Wildlife Service• Monitoring critical habitat• Biological Assessments
• EPA– Hazardous Material Spill
containment
• Etc.
Summary• HA-NDGPS signal successfully broadcast from
multiple locations– State-of-the-Art modulation– Reliable diplexing technology
• Developed new atmospheric modeling approaches
• Accuracy better than 10 cm horizontally, 95%• Availability above 99.9%• Implementation cost <$100,000 per site
Contact Information
Jim ArnoldFederal Highway Administration
Turner-Fairbank Highway research CenterMcLean, VA 22101
(202)493-3265
Phase I Test Reporthttp://www.tfhrc.gov/its/ndgps/02110/index.htm
Phase II Test Reporthttp://www.tfhrc.gov/its/pubs/05034/index.htm
Applications
The End
HIGH ACCURACY - NDGPS
Caretaker Sites New Site Coast Guard Site Green - Operating Red – Planned Dark Blue – HA-NDGPS Installed Light Blue – HA-NDGPS Planned
Hawk RunHawk Run
MaconMacon
GradyGrady
HackleburgHackleburg BoboBobo
GoodlandGoodland
TopekaTopeka
OnondagaOnondaga
MedfordMedford
EdinburgEdinburg
MedoraMedora
BillingsBillings
Great FallsGreat Falls
PolsonPolson SpokaneSpokane
AppletonAppleton
Klamath FallsKlamath Falls
AustinAustin
BakersfieldBakersfield
EssexEssex FlagstaffFlagstaff
AlbuquerqueAlbuquerque
SummerfieldSummerfield
PuebloPueblo
HudsonHudson FallsFalls
Whidbey IsWhidbey Is
Robinson PtRobinson Pt
Fort StevensFort Stevens
Cape Cape MendocinoMendocino
Pigeon PointPigeon Point
Point ArquelloPoint Arquello
Point LomaPoint Loma
Aransas PassAransas Pass
GalvestonGalveston
English TurnEnglish Turn
MobileMobilePointPoint
Egmont KeyEgmont Key
Key WestKey West
MiamiMiami
Cape CanaveralCape Canaveral
Fort MaconFort Macon
Cape HenryCape Henry
Cape HenlopenCape Henlopen
Sandy HookSandy Hook
MorichesMoriches
Millers FerryMillers Ferry VicksburgVicksburg
MemphisMemphis SallisawSallisaw
KansasKansasCityCity
St LouisSt Louis
RockRockIslandIsland
St. PaulSt. Paul
WisconsinWisconsin Point Point
UpperUpperKeweenawKeweenaw
Whitefish PtWhitefish PtNeebish IslandNeebish IslandCheboyganCheboygan
Sturgeon BaySturgeon Bay
DetroitDetroit
SaginawSaginawBayBay
MilwaukeeMilwaukee
YoungstownYoungstown
TucsonTucson MundayMunday
JacksonJackson
MytonMyton
El PasoEl Paso
INELINEL
DandridgeDandridge
CincinnatiCincinnati
MontereyMonterey
LangtryLangtry
RawlinsRawlins
WeiserWeiser
KanabKanab
HagerstownHagerstown
AshvilleAshville
MartinsvilleMartinsville
MiddleburyMiddlebury
Jack Jack CreekCreek
OdessaOdessa
GreensboroGreensboro
OmahaOmaha
Pine Pine RiverRiver
St. Mary’sSt. Mary’s
LouisvilleLouisville
ElmiraElmira
KensingtonKensington
FayettevilleFayettevilleNew BernNew Bern
AnnapolisAnnapolis
Canton Canton
Iowa CityIowa City
St Mary’sSt Mary’s
LedyardLedyard
SenecaSeneca
LincolnLincoln
WenatcheeWenatchee
WhitneyWhitney
ClarkClark
ChicoChico
PenobscotPenobscot
CharlestonCharleston
SavannahSavannah
HartsvilleHartsville
Reedy PointReedy Point
DriverDriver
PortsmouthPortsmouth
BrunswickBrunswick
AcushnetAcushnet
Pattern Pattern
The Broadcast• Broadcast Code and Carrier Phase Data
• Capability to broadcast all observables (L1,L2C,L5, and others) contained in less than 1000 bits
• Data rates - 1KBPS• Initially L1 and L2-P(Y) observables are broadcast
• Utilize an Advanced Broadcast Link• Data synchronized to GPS time• Carrier calibrated with GPS to sub-hertz levels• Spectrally efficient modulation (raised cosine MSK)• “One second data” in compact mode
Add Ons• National Geodetic Survey:
– Replacing Brass Survey Markers– Continuosly Operating Reference Station
• GPS in Weather:– Troposphere and Ionisphere Delays– Troposphere delay correlated Atmospheric Water
Vapor,
• Plate Boundary Observatory:– Used to measure plate movement.
• Etc.