The Global Positioning System for the Geosciences Summary and Proceedings of a Workshop on Improving the GPS Reference Station Infrastructure for Earth, Oceanic, and Atmospheric Science Applications (1997) / Chapter Skim
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7 Networks and Data Sources
7 Networks and Data Sources
Pages 40-109
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7 Networks and Data Sources
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These functions are performed at reference stations and master stations to generate the WAAS message for broadcast to users. Each WAAS reference station (WRS)
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Provide WAAS Message Broadcast and Ranging WAAS Communications GEO Satellite Broadcast GPS Signal The data verification function verifies the integrity of all data provided to WAAS users prior to transmission and validates that data. WAAS MESSAGE BROADCAST The WAAS message is computed at the reference stations and master stations and transmitted over existing FAA private data network communications systems.
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Wldc Asea Master S - 'on ~ Wide Area Reference Station · Wide Area Reference Station around Earth Station excluding outages of less than 5 minutes, is 1-~2 x 10-s) per hour for each element and the total system.
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Monuments for locating the GPS and geosynchronous communications satellite receive antennas will be US Geodetic Survey Federal Base Network Point or equivalent. The accuracy requirements specified are: · Horizontal: 5 cm · Ellipsoidal Height 10 cm Orthometric Height 10 cm NAVD 88 Antenna placement errors relative to the local monument are specified to be within 1 cm horizontal and 2 cm vertical.
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This DGPS service is available to the public navigator as an all-weather navigation sensor to supplement traditional visual, radar, and depth sounding techniques. The design process for the United States Coast Guard's DGPS service began with efforts to define system operational requirements.
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GPS satellites data consisting of CA code, PI and P2 Range, and L1 and L2 Carrier Phase information is collected every 30 seconds by the National Geodetic Survey (JIGS) from both Reference Stations at each broadcast site.
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SYSTEM PERFORMANCE [Broadcast Standard] -Accuracy- The position accuracy of the USCG DGPS Service is within 10 meters (2dnns)
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phase in which the service is available for positioning and navigation. Dunng IOC, enhancements to Control Station software and hardware Bill be accomplished, radiobeacon antennas will be upgraded to meet mission goals, transmitters mill be replaced with new state~f-the-art equipment which operate with battery backup, and the DGPS service will undergo validation.
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This is the most important issue we face as DGPS service providers. However, other users have found innovative ways to utilize DGPS services and where feasible, the Coast Guard DGPS network has expanded to meet their needs.
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9 ~110 1 811 I Egmont Key, FL 1 312 1 200 ~L 45.65 1 210 1 812 ~erto Rico ~29S ~100 1 18 ~12S 1 817 Mobile Point,AL 1 300 1 100 1 3013.65 1 8801.4S 1 170 1 813 I Engli3hTurn,I~A 1 293 1 200 1 2952~74 1 8956~0 1 170 1 814 Galveston,lX ~296 1 100 1 ~919.79 1 9444.21 1 180 1 8IS j I Aran3asPas3'l ~1 304 1 100 1 275030 1 9703~53 1 180 1 816 Great Lakes Region Broadcast Site | Frequency | T=n Rate | Latitude | Long ~de | Range | Radiobeacon L (k~)
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HI 313 310 298 292 288 323 302 323 1~BD 287 292 3'n 287 32~1 302 300 285 51 32 19.88 35 27.94 38 36.67 42 0050 44 18.25 32 05.40 35 22.00 39 07.07 90 55.19 90 1234 89 45~50 90 14.00 91 S4.23 87 23.73 94 95 24.88 * Great l ekes and Western Rivers DGPS sites indicate radiobeacon ranges in statute miles, all others are in nautical miles.
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Data is stored in receiver memory until the close of the UTC day, and then downloaded over telephone lines. UCB operates the Northern California Earthquake Data Center (Romanowicz et al., 1994)
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However, we will soon replace the fiberglass enclosure lids with plexiglass covers. There is now a delay of about 18 hours between the end of the UTC day and the availability of that day's data at the Northern California Earthquake Data Center.
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Webb, F.H., and J.F. Zumberge, 1993, An Introduction to GIPSY/OASIS-II, PL Publication D-11088, Jet Propulsion Laboratory, Pasadena, CA.
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and selves as one of seven IGS Analysis Centers producing improved ephemerides for the GPS constellation. In addition to these duties SOPAC senres as one of three primary archives of IGS global tacking data as well as a principal archive of continuous GPS data from the Southern California Integrated GPS Network (SCION)
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Receivers listed are those installed before May 1996; check individual site logs for complete site history. Institutions overseeing or assisting in the development of sites or subsets of PGGA sites: SIO, Scripps Institution of Oceanography; JPL, Jet Propulsion Laboratory; MIT, Massachusetts Institute of Technology; RCFC, Riverside County Flood Control; RCS, Riverside County Surveyors Office; OC, Orange County Environmental Management Office; GPO, Geothermal Program Office of the China Lake Naval Weapons Center; CIT, California Institute of Technology; UCLA, University of California, Los Angeles; INEGI, Mexican National Survey Office.
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Map of the Southern California Permanent GPS Geodetic Array (PGGA)
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SOPAC GPS PROCESSING A, Since November 1991, the SOPAC Analysis Center has been analyzing global GPS data to provide precise satellite ephemerides to the GPS community. The SOPAC analysis group now operates as one of 7 IGS analysis center.
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In addition to raw receiver files, the SOPAC archive holds precise ephemerides for the GPS constellation calculated by the 7 primary IGS analysis centers. For more near-real time needs, the SOPAC analysis center provides both a rapid and a predicted orbit in it's "combinations" directory.
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Liu and R.E. Neilan, eds., IGS Central Bureau, Jet Propulsion LaboratoIy, Pasadena, pp.
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61 APPENDIX A THE SOPAC GARNER ARCHIVE This is a short introduction to those who wish to access IGS and regional raw and RINEX data and improved orbits from the SOPAC archive. We have two levels of interaction and access to our data holdings, the GARNER ftp archive at toba.ucsd.edu, and the SOPAC home page on the World Wide Web at http://toba.
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1994, 1995; NOAA 19951. When supplemented with surface meteorological data, the GPS receivers incorporated into the network of CORS sites managed by NOAA National Geodetic Survey are adequate to make these measurements.
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We determined that a growing number of GPS receivers operated by other Federal agencies such as the U.S. Coast Guard (albeit for reasons other than atmospheric remote sensing)
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ADVANTAGES TO SlIARED USE OF DGPS SITES This approach provides us with an innovative solution to the problem of how to increase the number of GPS water vapor observing sites at very low cost, while simultaneously enhancing the value of these facilities to their users and the American Taxpayer. In particular, it leverages the $13 billion investment by DoD in the space and ground system segments of GPS, as well as the investments in GPS receivers and communications infrastructure made by other federal agencies such as USCG.
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The National Geodetic Survey Continuously Operating Reference System (CORS) , this voulme.
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Photos - see image and attached drawing Map and list of sites - see attached documentation Types of data and differential corrections provided - Half-hour data, 30-see samples. No differential corrections provided.
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- We are presently not a DGPS service provider. We are collaborating with NGS and USCG to acquire meteorological data at USCG DGPS sites that will be available to the CORS community.
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68 The Global Positioning System for the Geosciences ANTENNA INSTALLATION AT PLATTEVILLE
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Shared Use of DGPS Data for NOAA Weather Forecasting and Climate Monitoring /~~p ~ ERL GPS Continuously Operating Reference Stations 1~ :~: 4~W 4L 5 Principal Facts - Lamont ~ND:VSSC ~ ~\ ~ ° War \ ~ | White. NOAA Profiler Net~vo~Sitew/CORS | \~-N | He ~ d Future Site w/CORS O NOAA P:ot9er Network Site w/o CORS I GPS Hub | FTS-2000 Dedicated Came ~ 4800 bps j ~ ~ ~ F~1~r ~s Cornet I o ~ ~ 1,~O0Kilomett" ' j' PRINCIPAL FACTS FOR NOAA/ERL GPS SITES Station ID: EMNO Station Coord: 36.69 - 97.48 Receiver Mode} Number: Tremble 4000 SSE Receiver Part Number: 18292-41 Receiver Serial Number: 3327A03450 Antenna Part Number: 14632-00 Antenna Serial Number: 332SA68604 Antenna Height: 2.752m (a above ground)
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70 The Global Positioning System for file Geosciences Principal Facts - Plattev~le Station ID: PLTC Station Coord: 40.~8 -104.72 Receiver Mode} Number: 4000SSE Receiver Part Number: IS292-41 Receiver Serial Number: 3327A03457 Antenna Part Number: 14632-00 Antenna Serial Number: 332SA68606 Antenna Height: 2.698 m (~ above ground) Pressure Height: 1.71 m Installed: ~ I-3-94 Magnetic Declination: ~ 0.8667 E Principal Facts - Hilisboro Station ID: ARK Station Coord: 3 S.3 ~ -97.30 Receiver Mode!
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Shared Use of DGPS Data for NOAA Weather Forecasting and Climate Monitoring Pnncipal Facts - Haskell Station ID: HKLO Station Coord: 35.8~ -95.78 Receiver Mode} Number: 4000SSE Receiver Part Number: IS292-01 Receiver Serial Number: 3504A09470 (DOA 4-17 returned to Trimble 4-20-95) Receiver Senal Number: 3515Al0453 (Installed 4-19-95)
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72 The Global Positioning System for the Geosciences Principal Facts - Purcell Station ID: PRCO Station Coord: 34.98 -97.52 Receiver Mode] Number: Tremble 4000SSE Receiver Part Number: IS292-41 Receiver Serial Number: 3343A04269 Antenna Part Number: 14632-00 Antenna Serial Number: 3328A68603 Antenna Height: 3.
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of Japan alone has been operating two GPS networks with over 210 GPS receivers for over one year. These two networks, called GRAPES and COSMOS, will be combined and expanded, and a 610-station permanent GPS network will assume operation in Spring 1996 (Figure 1~.
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Average The Global Positioning System for the Geosciences spacing between sites will be ~ 30 km for all of Japan. Dual frequency P |
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The approach of using more than one software package at GSI mirrors the successful approach by the International GPS Service for Geodynamics (IGS)
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This use would require more frequent than once per day downloading of the data, and the availability of additional meteorological data such as temperature, pressure and humidity for the GPS sites. The current size of its networks and ambitious future plans clearly have established Japanese agencies as one of the world leaders in permanent GPS network applications.
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Epoch '92 on the other hand was scheduled as a two-week campaign for the purpose of serving as a first extension of the that part of the relatively sparse IGS Network analyzed on a daily basis by the IGS Analysis Centers. The 1992 IGS Test Campaign was successful beyond expectation.
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The Table is extracted from the summary information made available through CDDIS, one of three IGS Global Data Centers (Noll, 1996~. The 13 stations marked with (*
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Operational data centers are in direct contact with the tracking sites, regional data centers reduce traffic on electronic networks. The Global Data Centers are the main interface to the Analysis Centers and the IGS user community (concerning IGS tracking data and products)
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on the other hand on possible new products like ionosphere models, station-specific precipitable water content values with a high temporal resolution using the IGS network. All IGS Analysis Centers have to model tropospheric refraction.
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that similar statements will be true in a few years time with respect to atmosphere physics: Several IGS Analysis Centers (CODE, ESA, JPL) started producing ionosphere models using significantly Deferent procedures and observables.
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Introducing the Central Bureau Information System of the International GPS Service for Geodynamics., IGS Colleague Directory, December 1994, IGS Central Bureau (JPL)
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International GPS Service for Geodynamics ATTACHMENT 1: CURRENT IGS GPS DATA HOLDINGS AT GLOBAL DATA CENTERS IGS Electronic Report Tue Feb 27 1996 1 1 :43:09 PST, Message Number 2440 Author: CDDIS/Carey Noll Subject: Wk 0841 CDDIS Data Holdings TABLE 1 Current IGS GPS Data Holdings (as of 27-Feb-96 14:36) , IGS Operational Week 112/GPS Week 0841 (Febmary 18 through Febn~y 24, 1996; Days 96049 through 96055)
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Tromso* Tsukuba UCLA, Los Angeles The Global Positioning System for the Geosciences KERG KIRU KIT3 KOKB KOSG KOUR EBRE LPGS LBCH MADR MALI CASA MAST MATE MDO1 MCM4 ~VO METS MONP WLSN NLIB NYAL OHIG OAT2 ONSA PVEP PAMA JPLM DRAO PERT PIE1 PINT POTS QUIN REYK RCM5 SPK1 STJO SANT SIO3 SHAO SOL1 CRO1 TAEJ TAIW THU1 TIDB TROM TSKB UCLP Rogue SNR-8C XX Rogue SNR-8100 XX Rogue S~R-8000 XX Ro.gue SNR-8 XX _ Ro~ue SNR-12 XX _ Rogue SNR-8C XX Tnmble 4000 SSE XX Ro~ue SNR-8000 XX _ Ro~e SNR-8000 XX Ro~e SNR-8 XX Rogue SNR-8C XX Ro.gue SNR-8000 XX _ ~ Ro~ue SNR-8100 XX _ .
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International GPS~-Service for Geodynamics 85 USC, Los Angeles | USC1 | Rogue Sl lR-8000 | X | ~| | X | X | 7 = Usuda USVD Rogue SNR-8000 X X ... X X 7 Vandenberg VNDP Ashtech LPZ-XIID X X ...
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To further aid users of IGS data and products, the IGS Central Bureau Information System (CBIS) was developed to provide information on IGS sites and participating data and analysis centers.
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IGS Products Seven IGS data analysis centers (ACs) retrieve the GPS tracking data daily from the global data centers to produce IGS data.
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IGS regional data centers have been established in several areas, including Europe and Australia. The IGS global data centers are ideally the principle GPS data source for the IGS analysis centers and the general user community.
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The CBIS contains information about: IGS organization and operation global network of GPS tracking sites general descriptions of GPS receivers and antennas access information and data holdings summaries for the IGS data centers descriptions of GPS data flow up-to-date data and product availability charts GPS system status IGS electronic mail archives software for general use (e.g., UN] X-compatible compress/decompress routines for various platforms)
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As stated previously, the role of the CDDIS in the IGS is to serve as one of three global data centers. In this capacity, the CDDIS is responsible for archiving and providing access to both GPS data from the global IGS network as well as the products derived from the analysis of these data.
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These reports are distributed via the IGS reporting mechanisms and stored on-line for ftp download or browsing through the WWW. The derived products from the IGS Analysis Centers are also delivered to the CDDIS, usually within seven days of the end of the observation week; the combined products produced by the IGS Analysis Coordinator are available a few days following the arrival of all product files from the individual ACs, typically within ten days.
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Figure 4 shows these statistics in hours for the current set of"global stations", those stations processed by three or more IGS Analysis Centers on a daily basis.
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The IGS tracking stations and data centers hope to furler improve these statistics by testing new procedures to push data to the global data centers even faster. This already remarkable statistic would not have been possible, however, without the adoption of standards in data formatting and compression.
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94 40,000 35,000 .' 30,000 ~ 25,000 E 20,000 1 5 ooo a' ~ 1 0,000 5,oo 0 0 .~ c~ Data Vol ume _ - ~ Number of Files The Global Positionin~: System for the Geosciences u~ ~ u~ 4D ~ u~ ut u~ ~ u~ ~ 03 ~ ~ 03 0 ~o~ o ~ o~ ~ 03 0~ ~ ~o~ ~ ~ ~ o~ ~ 0 .
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CONCLUSIONS The IGS has shown that near real-time availability of GPS data is a realibr. The hierarchy that was established in both tracking stations and data centers has streamlined data flow, with the global data center sensing as the main interface between the data and the user.
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W "Extending the National Geodetic Survey Standard Orbit Formats" in NOVA Technical Report ZOOS 133 NG5 46.
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At the top level of the CBIS one views the following: The IGS accomplishes its mission through the following components: a network of about 50 globally distributed permanent Tracking Stations; several Operational Centers operating parts of the global network; global and several regional Data Centers; currently 7 Analysis Centers and several Associate Analysis Centers, a Central Bureau located at the Jet Propulsion Laboratory and; a Governing Board. The charter of the IGS is defined in the Terms of Reference.
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CDDIS SOP address catalog directoIy.txt IGS Colleague Directory text dose.adr DOSEMail distribution list igsmail.adr IGSMail distribution list igsrepo~adr IGSReportdismbution list scign.adr SCIGNMail distribution list igsmail IGSMESS.INDEX IGSMail message index ig~mess.'rmn' IGSMail messages igereport IGSREPORT.INDEX IGS Report index igsreport 'rem' IGS Reports regional DOSE DOSEMail archive SCION SCIGNMail archive product 'w~vww' igs~7.e~p IGS earth rotation parameters igs~[O~] .sp3 IGS combined daily orbits igs~.sum IGS weekly product summary holding 'centef.prd analysis center product holdings iers bulletinb.'nn' IERS earth orientation eop90cO4.W IERS earth rotation parameters resource g boar~igs IGS Governing Board resource'nn'.ps IGSResourcelnformation (PostScript)
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All global stations that are part of the IGS Network are forwarded daily to the CDDIS Global Data Center at the Goddard Space Flight Center. The data is uploaded automatically via telephone lines or direct serial connections using Microphone Pro scripts no ing on Macintosh computers.
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. 1 1 FIGURE 1 JPL operated permanent GPS reference stations.
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GPS Operations and Data Handling at JPL ~ can o a)
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Tree Structure /pub /rinex ~ 001 . ,i,\~ etc Iraw 001 ,\~ etc /software /does Historical Data: RINEX data for all sites archived by JPL for last 90 days Receiver raw data for all sites operated by JPL and various others for last 25 days JPL software for data conversions various documentation and IGSMai!
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Raw GPS data is taken directly from the receiver to a Packet Assembler/Disassembler (PAD) , placed in packets, and transmitted to the CDF within milliseconds after it is observed.
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104 The Global Positioning System for the Geosciences W~ mono ~ ~O J ~ ~C)
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. The data from these stations is downloaded daily over BERNET from the CDDIS data center located at NASA Goddard Space Flight Center.
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The secondary acquisition computer continually queries the The Global Positioning System for the Geosciences primary acquisition computer to determine if it is functioning. If it finds the primary acquisition computer has failed to function, the secondary computer will automatically take over the data acquisition function.
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National Geodetic Survey Continuously Operating Reference System fCORS)
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tree (this file) The Global Positioning System for the Geosciences coral - - - ~ yyddd -- jaite id |cors2 -- -j yyddd -- jsite id |itrf92*
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NGS is working with the USCG to determine the magnitude of multipath at the USCG sites, to 109 determine the effectiveness of improved antenna types in decreasing multipath and to develop multipath models on a sit specific basis. Antenna stability is of great interest to scientific users of CORS data.
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