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

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GPS Predictable Accuracy64. The specific capabilities provided by SPS are established by DoD and DOT and arepublished in <strong>the</strong> Global Positioning System Standard Positioning Service Performance Standard(formerly known as <strong>the</strong> SPS Signal Specification, Ref. 7) available through <strong>the</strong> USCG NavigationInformation Service. The figures are 95% accurate and express <strong>the</strong> value <strong>of</strong> two standarddeviations <strong>of</strong> radial error from <strong>the</strong> actual antenna position to an ensemble <strong>of</strong> position estimatesmade under specified satellite elevation angle (five degrees) and PDOP (less than six) conditions.For horizontal accuracy figures, 95% is <strong>the</strong> equivalent <strong>of</strong> 2drms (two-distance root-meansquared),or twice <strong>the</strong> radial error standard deviation. For vertical and time errors, 95% is <strong>the</strong>value <strong>of</strong> two-standard deviations <strong>of</strong> vertical error or time error.65. Receiver manufacturers may use o<strong>the</strong>r accuracy measurements. Root-mean-square(RMS) error is <strong>the</strong> value <strong>of</strong> one standard deviation (68%) <strong>of</strong> <strong>the</strong> error in one, two or threedimensions.66. Circular Error Probable (CEP) is <strong>the</strong> value <strong>of</strong> <strong>the</strong> radius <strong>of</strong> a circle, centred at <strong>the</strong> actualposition that contains 50% <strong>of</strong> <strong>the</strong> position estimates. Spherical Error Probable (SEP) is <strong>the</strong>spherical equivalent <strong>of</strong> CEP, which is <strong>the</strong> radius <strong>of</strong> a sphere, centred at <strong>the</strong> actual position thatcontains 50% <strong>of</strong> <strong>the</strong> three dimension position estimates. As opposed to 2drms, drms, or RMSfigures, CEP and SEP are not affected by large blunder errors making <strong>the</strong>m an overly optimisticaccuracy measure.67. Some receiver specification sheets list horizontal accuracy in RMS or CEP and withoutSelective Availability, making those receivers appear more accurate than those specified by moreresponsible vendors using more conservative error measures.GPS satellite signals68. The SVs transmit two microwave carrier signals. The L1 frequency (1575.42 MHz)carries <strong>the</strong> navigation message and <strong>the</strong> SPS code signals. The L2 (1227.60 MHz) and L1frequencies (1575.42 MHz) are used to measure <strong>the</strong> ionospheric delay by PPS equipped receivers.Three binary codes shift <strong>the</strong> L1 and/or L2 carrier phase. The C/A Code (Coarse Acquisition)modulates <strong>the</strong> L1 carrier phase. The C/A code is a repeating 1 MHz Pseudo Random Noise(PRN) Code. This noise-like code modulates <strong>the</strong> L1 carrier signal, "spreading" <strong>the</strong> spectrum overa 1 MHz bandwidth.69. The C/A code repeats every 1023 bits (one millisecond). There is a different C/A codePRN for each SV. Their PRN number, <strong>the</strong> unique identifier for each pseudo-random-noise code,<strong>of</strong>ten identifies GPS satellites. The C/A code that modulates <strong>the</strong> L1 carrier is <strong>the</strong> basis for <strong>the</strong>civil SPS. The P-Code (Precise) modulates both <strong>the</strong> L1 and L2 carrier phases. The P-Code is avery long (seven days) 10 MHz PRN code. In <strong>the</strong> Anti-Spo<strong>of</strong>ing (AS) mode <strong>of</strong> operation, <strong>the</strong> P-Code is encrypted into <strong>the</strong> Y-Code.70. The encrypted Y-Code requires a classified AS Module for each receiver channel and isfor use only by authorised users with cryptographic keys. The P (Y)-Code is <strong>the</strong> basis for <strong>the</strong>PPS. The Navigation Message also modulates <strong>the</strong> L1-C/A code signal. The Navigation Messageis a 50 Hz signal consisting <strong>of</strong> data bits that describe <strong>the</strong> GPS satellite orbits, clock corrections,and o<strong>the</strong>r system parameters.18
71. The GPS Navigation Message consists <strong>of</strong> time-tagged data bits marking <strong>the</strong> time <strong>of</strong>transmission <strong>of</strong> each sub-frame at <strong>the</strong> time <strong>the</strong>y are transmitted by <strong>the</strong> SV. A data bit frameconsists <strong>of</strong> 1500 bits divided into five 300-bit sub-frames. A data frame is transmitted every thirtyseconds. Three six-second sub-frames contain orbital and clock data. SV Clock corrections aresent in sub-frame one and precise SV orbital data sets (ephemeris data parameters) for <strong>the</strong>transmitting SV are sent in sub-frames two and three. Sub-frames four and five are used totransmit different pages <strong>of</strong> system data. An entire set <strong>of</strong> twenty-five frames (125 sub-frames)makes up <strong>the</strong> complete Navigation Message that is sent over a 12.5 minute period.2. GLONASSRussian satellite navigation policy72. The Global Navigation Satellite System “GLONASS” is able to provide unlimitednumber <strong>of</strong> air, maritime, and any o<strong>the</strong>r type <strong>of</strong> users with all-wea<strong>the</strong>r three-dimensionalpositioning, velocity measuring and timing anywhere in <strong>the</strong> world or near-Earth space.73. Designed mainly for military purposes, <strong>the</strong> Russian GLONASS system had been fullydeployed in 1995 with a constellation <strong>of</strong> 24 satellites. At <strong>the</strong> same time, GLONASS is availablefor civil users with <strong>the</strong> L1 signal <strong>of</strong> <strong>the</strong> Standard Accuracy without any selective availability.Since that time, <strong>the</strong> Russian Government has declared open access free <strong>of</strong> charge to <strong>the</strong> standardaccuracy positioning service for civil users.74. Since 1999, <strong>the</strong> Russian authorities have consistently implemented <strong>action</strong>s to presentGLONASS service for civil users. Two basic decisions (Presidential Directive <strong>of</strong> 18 February1999 (38) and following <strong>the</strong> Governmental Decision <strong>of</strong> 29 March 1999 (346)) defined <strong>the</strong>GLONASS status as a dual-use system opened for international co-operation. Two StateCustomers <strong>of</strong> <strong>the</strong> GLONASS system have been defined: <strong>the</strong> Ministry <strong>of</strong> Defense and <strong>the</strong> RussianAviation and Space Agency (civil institution, now <strong>the</strong> Russian Federal Space Agency).75. As a dual-use system GLONASS is available for <strong>the</strong> civil community worldwide andincludes <strong>the</strong> following characteristics:• Free use <strong>of</strong> <strong>the</strong> civil signal globally;• Civil signal specification available for both users and industry (Interface ControlDocument); and• No selective availability for civil signal since start <strong>of</strong> operation (has not been foreseen bydesign).76. In <strong>the</strong> following governmental decision on <strong>the</strong> GLONASS use (3 August 1999 (896)) <strong>the</strong>combined GNSS receivers (GLONASS/GPS) application has been recommended for users.77. GLONASS, as a system opened for international co-operation, has been presented as abasis to implement international global navigation satellite systems. The negotiations with <strong>the</strong>European Union (EU) at <strong>the</strong> beginning phase could lead to <strong>the</strong> EU/Russia international GNSSbased on GLONASS and GALILEO. At least three global basic systems will combine <strong>the</strong> coreGNSS: GPS, GLONASS, GALILEO. The main objective is to ensure compatibility andinteroperability, by providing better performance and reliability <strong>of</strong> <strong>the</strong> navigation service forusers all over <strong>the</strong> world.19
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 and 14: virtually every facet of</s
Page 15 and 16: 27. Time and frequency disseminatio
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: Service Availability Standard62. Th
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
Page 65 and 66: 326. The regional activity in <stro
Page 67 and 68: GNSS SBAS-WAAS trials in th
Page 69 and 70: 356. Other activit
Page 71 and 72: with respect to the</strong
Page 73 and 74: 379. Argentina has at present a “
Page 75 and 76:
Brazilian Continuous GPS Network (R
Page 77 and 78:
all mapping-related works in <stron
Page 79 and 80:
monitoring, national reference <str
Page 81 and 82:
Programs: B.Sc/M.Sc/Ph.D. in geomat
Page 83 and 84:
• University of
Page 85 and 86:
V. NEEDS AND CONCERNS OF DEVELOPING
Page 87 and 88:
Surveying, Mapping, Land Use• Pre
Page 89 and 90:
include Special Implementation Proj
Page 91 and 92:
VI.EXISTING TRAINING OPPORTUNITIES
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465. Many other GN
Page 95 and 96:
• Theory and practice of<
Page 97 and 98:
D. GNSS training opportunities <str
Page 99 and 100:
VII.INSTITUTIONAL MODELS FOR INTERN
Page 101 and 102:
Environment Programme (UNEP), and <
Page 103 and 104:
appropriate national security reaso
Page 105 and 106:
VIII.RECOMMENDATIONS541. A number <
Page 107 and 108:
for Outer Space Affairs, developmen
Page 109 and 110:
• Develop the sk
Page 111 and 112:
Recommendation 2. The development <
Page 113 and 114:
583. The need to develop th
Page 115 and 116:
589. Project 2:Pilot Projects (4 pr
Page 117 and 118:
Annex I: Indian universities, resea
Page 119 and 120:
University/researchinstitute/compan
Page 121 and 122:
Annex III: Italian universities and
Page 123 and 124:
Annex IV: Italian non-governmental
Page 125 and 126:
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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