FGCS-FIXED REFERENCE STATION WORKGROUP
A. ACTIVITIES AT THE NGS
B. WHAT ARE THE ACTIVITIES OF OTHER AGENCIES?
C. WHAT ARE THE NEEDS OF THE FGCS?
REAL-TIME ACTIVITIES AT THE NGSI. OPERATE AN NTRIP CASTER (Fed. Owned/operated –
currently 6, soon 9)
II. DEVELOP AND PUBLISH GUIDELINES DESCRIBING BEST PRACTICES.(RTK Users draft, RTN Operators draft, etc.)
III. PARTICIPATE IN MEETINGS, FORUMS, WORKSHOPS, ETC., CONCERNING REAL-TIME NETWORKS. SEEK LEADERSHIP ROLES.(FIG, ESRI, ACSM, RTCM, etc.)
IV. RESEARCH PHENOMENA AFFECTING ACCURATE REAL-TIME POSITIONING. (HTDP, IDOP, GEOID08, etc.)
POSITIONING
GPS/GNSS POSITIONINGPASSIVE MONUMENTS ACTIVE STATIONS
STATICNGS 58/59 GUIDELINES RTNFGCS ACCURACY STDS. VRS MAC FKPMFTRS. SOFTWARE & DOCS. ½ COST OR DOUBLE WORK DONE
OPERATORS DRAFT GUIDELINES
≈ 75 IN USA, 200+ WORLDWIDE
REAL-TIMESINGLE BASE MONUMENTSCLOSEST BASE CORSNGS CLASSICAL USER GUIDELINES-DRAFT
I. NGS Real Time Stream TeamProduct Manager
Richard SnayOutreach and User Relations
Bill HenningPam Fromhertz
CORS Data StreamsCharlie SchwarzNeil WestonGiovanni Sella
IT TeamBruce SailerHong ChenSky Chaleff
Supporting New ProductsReal time - essential that CORS/NGS supports this activity.TO DO: compute ultra-rapid orbits, QC coordinates, provide data-streams. Currently CORS only supports 6 sites with limited data-streams
GNSS: add GLONASS and new GPS frequencies to online storage in 2008
OPUS-flavorsNOAA-sister productsSpace Weather Prediction Center
went operational in 2007GPS Met Program will go
operational in 2010Co-Ops coordinates for NWLON
GNSS sites
1200 + 400 TO BE ADDED IN 2008
MDSI
HNPT
NGS HEADQUARTERS
NGS TESTING SITES – CORS STATIONS HNPT, MDSI, VAGP, PRMI VAGP
NGS TESTING SITES –PRMI, VITH, VIKH
VITH
PRMI
VIKH
NGS TESTING SITES –BARH ON LINE SOON
BARH
COLLEGE OF THE ATLANTIC GIS LABORATORY
EPRT
CORB
WELCOME & LINKS PAGEhttp://www.ngs.noaa.gov/CORS-Proxy/NGSRealtimeGNSS/welcomeNGSNtrip.jsp
DATA STREAM WEB PAGE
RTCM 3.0 MESSAGE TYPES FROM NGS CORS
NOT
II. RT POSITIONING GUIDELINES
-
GUIDELINES, SPECS, STANDARDS √ SINGLE-BASE USER – DRAFT OUT
RTN PLANNING & NETWORK DESIGN
RTN CONSTRUCTION/SITE EVALUATION
RTN ADMINISTRATIVE
RTN USER
RTN TEAM – ADVISORS AND PARTNERS
http://www.ngs.noaa.gov/WHY SINGLE-
BASE?-ACCOMMODATE LEGACY USERS- CLOSEST BASE NETWORKS-AREAS WITH NO CELL COVERAGE- PROJECT SITE APPLICATIONS, SUCH AS MACHINE CONTROL
WHY EMPIRICAL?
-PLETHORA OF VARIABLES-TIMELINESS-PORT TO RTN USERS-DYNAMIC NATURE OF RT POSITIONING
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 datumslocal and national datums- GPS, GLONASS, Galileo, Compass Constellations
RT SINGLE-BASE ACCURACY CLASSES
NGS HOME WEB PAGE
ACADEMIC/SCIENTIFICSPATIAL REFERENCE CENTERSVARIOUS DOTSCOUNTYCITYGEODETIC SURVEYS (NC, SC)MANUFACTURERSVENDOR NETWORKSAGRICULTUREMA & PA NETWORKS
EXAMPLES OF RTN ADMINISTRATORS IN THE USA
RAPIDLYGROWING
REAL TIME NETWORKS (RTN)
• HOW ARE THEY ESTABLISHED? • HOW ARE THEIR COORDINATES
COMPUTED? ARE THEY CONSISTENT? • HOW IS THE NETWORK ADJUSTED? • HOW DOES THE RTN ALIGN TO THE NSRS? • CAN USERS USE ANY MANUFACTURERS’
EQUIPMENT IN THE RTN?• DO OVERLAPPING NETWORKS GIVE THE
SAME COORDINATES?• WHAT ARE THE FIELD ACCURACIES?
?
3. Develop standards, specifications, and guidelines for administrating RTN. This may include: a. Reference station siting and construction considerations. b. Policy to promote the use of open source, generic data formats such as RTCM via the use of the most current Networked Transport of RTCM via Internet Protocol (NTRIP) programs. d. Policy to encourage the RTN to support as many different GNSS hardware and firmware packages as possible. e. Guidelines to recommend methods to enable RTN results to be aligned with the NSRS. This may include methods to archive and quality check RTN data. f. Guidelines to recommend methods to determine accurate positional coordinates and velocities for RTN reference stations.
II. RTN GUIDELINES IN NGS POLICY STATEMENT
ftp://ftp.ngs.noaa.gov/dist/whenning/RTNteam/REVIEW/RTpolicy.June2008.doc
OPERATING A RTN- CHAPTER ONE DRAFTftp://ftp.ngs.noaa.gov/dist/whenning/RTNteam/REVIEW/
•#1 Include a subnetwork of the RTN into the National 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 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.
RTNguidelines.June08.doc
BAKERSFIELD2 CORS- SEASONAL N/S & VERTICAL MOVEMENT
2002 2003 2004 2005 2006 2007 2008
2002 2003 2004 2005 2006 2007 2008
2002 2003 2004 2005 2006 2007 2008
EXAMPLE OF WHY RTN REFERENCE STATIONS SHOULD BE MONITORED
≈ 6 MM / YEARENGLISH TURN CORS
SUBSIDENCE
IDOP WITH SCALE COULD CORRELATE TO ACCURACY
III.
IDOP VALUES – 4 CORS EXAMPLEBEST IDOP = 1 √ N
THEREFORE, WITH 9 CORS, THE IDOP AT THE CENTROID WOULD BE .33, WITH 4 CORS IT WOULD BE .5 AT THE CENTROID
ADDITION OF RMS OF DISTANCE TO
CORS CONTRIBUTING TO
THE SOLUTION GIVES FINAL
UNITLESS NUMBER
.87.87
.87 .87
.5
.6.7
.8
.8
.7
.6
“IDOP” WILL BE THE SUBJECT OF A FORTHCOMING PAPER BY DRS. RICHARD SNAY, TOM SOLER AND CHARLES SCHWARZ
OPUS-RS Accuracyfor 15-minute data sets
0
1
2
3
4
5
6
7
0 0.2 0.4 0.6 0.8 1
IDOP
Std.
Err
. (cm
)
East-West North-South Ellipsoid Height
ACTIVITIES IN OTHER AGENCIES?
WHAT GUIDANCE OR PRODUCTS ARE NEEDED?
WORKGROUP ISSUES
ftp://ftp.ngs.noaa.gov/dist/whenning/FGCS