report of the action team on global navigation satellite systems (gnss)

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• Planet Quest:http://planetquest.jpl.nasa.gov/• U.S. Coast Guard Navigation Center:http://www.navcen.uscg.gov/• U.S. Mission to <strong>the</strong> European Union: GPS and <strong>the</strong> EU's GALILEO Systemhttp://www.useu.be/Galileo/• U.S. Space Objects Registry:http://www.usspaceobjectsregistry.state.gov/Global Positioning System description22. GPS is a Satellite Navigation System with many millions <strong>of</strong> civil users worldwide. GPSprovides specially coded satellite signals that can be processed in a GPS receiver, enabling <strong>the</strong>receiver to compute position, velocity and time. At least four GPS satellite signals are necessaryto compute positions in three dimensions and <strong>the</strong> time <strong>of</strong>fset in <strong>the</strong> receiver clock. With aReceiver Autonomous Integrity Monitoring (RAIM) capable receiver and six in view GPSsatellites allow <strong>the</strong> users to achieve RAIM. The Space Segment <strong>of</strong> <strong>the</strong> system consists <strong>of</strong> <strong>the</strong> GPSsatellites. These space vehicles (SVs) send radio signals from space. The nominal GPSOperational Constellation consists <strong>of</strong> 24 satellites plus on-orbit spares that orbit <strong>the</strong> Earth in 12hours. There are <strong>of</strong>ten more than 24 operational satellites as new ones are launched to replaceolder satellites.23. The satellite orbits repeat almost <strong>the</strong> same ground track (as <strong>the</strong> Earth turns beneath <strong>the</strong>m)once each day. The orbit altitude is such that <strong>the</strong> satellites repeat <strong>the</strong> same track and configurationover any point approximately each 24 hours (4 minutes earlier each day). There are six orbitalplanes (with nominally four SVs in each), and inclined at about fifty-five degrees with respect to<strong>the</strong> equatorial plane. This constellation provides <strong>the</strong> user with between five and eight SVs visiblefrom any point on <strong>the</strong> Earth.Control Segment24. The Control Segment consists <strong>of</strong> a system <strong>of</strong> tracking stations located around <strong>the</strong> world,including <strong>the</strong> GPS Master Control and Monitor Network. The Master Control facility is located atSchriever Air Force Base (formerly Falcon AFB) in Colorado. These monitor stations measuresignals from <strong>the</strong> SVs, which are incorporated into orbital models for each satellite. The modelscompute precise orbital data (ephemeris) and SV clock corrections for each satellite. The MasterControl station uploads ephemeris and clock data to <strong>the</strong> SVs. The SVs <strong>the</strong>n send subsets <strong>of</strong> <strong>the</strong>orbital ephemeris data to GPS receivers over radio signals.25. The GPS User Segment consists <strong>of</strong> <strong>the</strong> GPS receivers and <strong>the</strong> user community. GPSreceivers convert SV signals into position, velocity, and time estimates. Four satellites arerequired to compute <strong>the</strong> four dimensions <strong>of</strong> X, Y, Z (position) and Time.26. GPS receivers are used for navigation, positioning, time dissemination, remote clockcomparison and for o<strong>the</strong>r research purposes. Navigation in three dimensions is <strong>the</strong> primaryfunction <strong>of</strong> GPS. Navigation receivers are made for aircraft, ships, ground vehicles and for handcarrying by individuals. Enhanced positioning is possible using GPS receivers at referencelocations providing corrections and relative positioning data for remote receivers. Surveying,geodetic control, and plate tectonic studies are some examples.8
27. Time and frequency dissemination, based on <strong>the</strong> precise clocks on board <strong>the</strong> SVs andcontrolled by <strong>the</strong> monitor stations, constitutes ano<strong>the</strong>r use for GPS. Astronomical observatories,telecommunications facilities, and laboratory standards can be set to precise time signals orcontrolled to accurate frequencies by special purpose GPS receivers. Research projects have usedGPS signals to measure atmospheric parameters. The elaboration <strong>of</strong> <strong>the</strong> international referencetime scales relies mostly on clock comparison using <strong>the</strong> atomic clocks on board GPS satellites.Precise Positioning Service (PPS)28. Authorised users with cryptographic equipment and keys and specially equippedreceivers use <strong>the</strong> Precise Positioning System. The United States and allied military, certain UnitedStates Government agencies and selected civil users specifically approved by <strong>the</strong> United StatesGovernment can use <strong>the</strong> PPS.29. PPS Predictable Accuracy:• 22-meter horizontal accuracy• 27.7-meter vertical accuracy• 200-nanosecond time Coordinated Universal Time (UTC) accuracyStandard Positioning Service (SPS)30. Civil users worldwide use <strong>the</strong> SPS without charge or restrictions. Most receivers arecapable <strong>of</strong> receiving and using <strong>the</strong> SPS signal.The GPS Standard Positioning Service31. The GPS SPS is a positioning and timing service provided on <strong>the</strong> GPS L1 signal. The L1signal, transmitted by all GPS satellites, contains a Coarse/Acquisition (C/A) code and anavigation data message. The GPS L1 signal also contains a Precision P (Y) code that is reservedfor military use and is not a part <strong>of</strong> <strong>the</strong> SPS.32. The L-band SPS ranging signal is a 2.046 MHz null-to-null bandwidth signal centredabout L1. The transmitted ranging signal that comprises <strong>the</strong> GPS-SPS is not limited to <strong>the</strong> null-tonullsignal and extends through <strong>the</strong> band 1563.42 to 1587.42 MHz. GPS satellites also transmit asecond ranging signal known as L2. The L2 signal is not part <strong>of</strong> <strong>the</strong> SPS. Therefore, SPSperformance standards are not predicated upon use <strong>of</strong> L2, or use <strong>of</strong> L1/L2 carrier tracking foro<strong>the</strong>r than code acquisition and tracking purposes.33. Until such time as a second coded civil GPS signal is operational, <strong>the</strong> United StatesGovernment has agreed to not intentionally reduce <strong>the</strong> current received minimum RadioFrequency signal strength <strong>of</strong> <strong>the</strong> P (Y)-coded signal on <strong>the</strong> L2 link, as specified in ICD-GPS-200C or to intentionally alter <strong>the</strong> P (Y)-coded signal on <strong>the</strong> L2 link. This does not precludeaddition <strong>of</strong> codes or modifications to <strong>the</strong> L2 signal, which do not change, or make unusable, <strong>the</strong>L2 P (Y)-coded signal as currently specified.Global Positioning System overview34. Detailed information is provided below to promote a common understanding <strong>of</strong> <strong>the</strong>nominal GPS baseline configuration.9
Page 1 and 2: REPORT OF THE ACTION TEAM ONGLOBAL
Page 3 and 4: This document has not been formally
Page 5 and 6: CONTENTSIntroduction ..............
Page 7 and 8: REPORT OF THE ACTION TEAMON GLOBAL
Page 9 and 10: Product4. The product of</s
Page 11 and 12: II.OVERVIEW OF PLANNED AND EXISTING
Page 13: virtually every facet of</s
Page 17 and 18: Service Availability Standard39. Th
Page 19 and 20: Table 1-4. Service Reliability Stan
Page 21 and 22: 50. The GPS Control Segment (CS) is
Page 23 and 24: Service Availability Standard62. Th
Page 25 and 26: 71. The GPS Navigation Message cons
Page 27 and 28: the Board, mainly
Page 29 and 30: • Vertical :• Velocity:• User
Page 31 and 32: • The network of
Page 33 and 34: 126. The EU and ESA have concluded
Page 35 and 36: • The Search and Rescue Service (
Page 37 and 38: invitation to tender to this effect
Page 39 and 40: 2. EGNOS169. As previously mentione
Page 41 and 42: 183. Three phases have been identif
Page 43 and 44: an air navigation service dedicated
Page 45 and 46: • Aviation: a representative desi
Page 47 and 48: 222. The information is openly avai
Page 49 and 50: 234. The United Nations Office for
Page 51 and 52: • Provide consultancy and advice
Page 53 and 54: 255. Methods to compare distant clo
Page 55 and 56: measurements are used to evaluate <
Page 57 and 58: market can begin to develop. That a
Page 59 and 60: Nations and voluntary contributions
Page 61 and 62: IV.GNSS APPLICATIONSA. General appl
Page 63 and 64: 317. Agricultural applications incl
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326. The regional activity in <stro
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GNSS SBAS-WAAS trials in th
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356. Other activit
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with respect to the</strong
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379. Argentina has at present a “
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Brazilian Continuous GPS Network (R
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all mapping-related works in <stron
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monitoring, national reference <str
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Programs: B.Sc/M.Sc/Ph.D. in geomat
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• University of
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V. NEEDS AND CONCERNS OF DEVELOPING
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Surveying, Mapping, Land Use• Pre
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include Special Implementation Proj
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VI.EXISTING TRAINING OPPORTUNITIES
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465. Many other GN
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• Theory and practice of<
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D. GNSS training opportunities <str
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VII.INSTITUTIONAL MODELS FOR INTERN
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Environment Programme (UNEP), and <
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appropriate national security reaso
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VIII.RECOMMENDATIONS541. A number <
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for Outer Space Affairs, developmen
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• Develop the sk
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Recommendation 2. The development <
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583. The need to develop th
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589. Project 2:Pilot Projects (4 pr
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Annex I: Indian universities, resea
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University/researchinstitute/compan
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Annex III: Italian universities and
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Annex IV: Italian non-governmental
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Annex IV: Italian non-governmental
Page 127 and 128:
APPENDIXList of we
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report of the action team on global navigation satellite systems (gnss)

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