PART0 » History » Version 6
COLIN, Tony, 03/03/2016 12:24 PM
| 1 | 3 | COLIN, Tony | h1. PART 1 : An introduction to Navigation. |
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| 2 | 3 | COLIN, Tony | |
| 3 | 3 | COLIN, Tony | {{>toc}} |
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| 5 | 3 | COLIN, Tony | p=. !32.png! |
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| 7 | 3 | COLIN, Tony | p(. Before anything else, it is necessary to tackle the origin of navigation and its applications, the creation of the current GNSS with a comparison of different systems and finally, describing the main principles of GPS. |
| 8 | 3 | COLIN, Tony | |
| 9 | 3 | COLIN, Tony | --- |
| 10 | 3 | COLIN, Tony | |
| 11 | 3 | COLIN, Tony | h2. 1 - History of Navigation. |
| 12 | 3 | COLIN, Tony | |
| 13 | 3 | COLIN, Tony | _*Navigation* is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another.[1] The field of navigation includes four general categories: land navigation, marine navigation, aeronautic navigation, and space navigation._ |
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| 15 | 4 | COLIN, Tony | p=. !33.jpg! !34.jpg! !35.jpg! !37.jpg! !36.jpg! |
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| 17 | 3 | COLIN, Tony | h3. a- Visual navigation. |
| 18 | 3 | COLIN, Tony | |
| 19 | 3 | COLIN, Tony | Seamark and landmark references > Limited range, Limited accuracy, Low availability of marks, Stars only during night and clear sky. |
| 20 | 3 | COLIN, Tony | |
| 21 | 3 | COLIN, Tony | h3. b- Navigation with classic instruments |
| 22 | 3 | COLIN, Tony | |
| 23 | 3 | COLIN, Tony | Magnetic compass, Sextant > Measurement of the height of stars above the horizon providing longitude inaccurately > Use of ephemeris and time reference |
| 24 | 3 | COLIN, Tony | Improvements by combining it with Harrison's clock (Chronometer) providing latitude and longitude with acceptable accuracy. |
| 25 | 3 | COLIN, Tony | |
| 26 | 3 | COLIN, Tony | --- |
| 27 | 3 | COLIN, Tony | |
| 28 | 3 | COLIN, Tony | h2. 2 - Global Navigation Satellite System (GNSS). |
| 29 | 3 | COLIN, Tony | |
| 30 | 3 | COLIN, Tony | h3. a- History. |
| 31 | 3 | COLIN, Tony | |
| 32 | 3 | COLIN, Tony | - *Sputnik* in 1957 : first satellite in the world, orbit estimated using the received signal frequency : Doppler effect. |
| 33 | 3 | COLIN, Tony | - *TRANSIT* from 1958 operational in 1964 : first satellite navigation system for the US Navy. |
| 34 | 3 | COLIN, Tony | - *GPS* program started at 1973 providing position anywhere at anytime. |
| 35 | 3 | COLIN, Tony | |
| 36 | 3 | COLIN, Tony | h3. b- Current definition. |
| 37 | 3 | COLIN, Tony | |
| 38 | 3 | COLIN, Tony | _*Global Navigation Satellite System (GNSS)* is a system of satellites that provide autonomous spatial positioning on Earth with global coverage. |
| 39 | 3 | COLIN, Tony | It allows small electronic receivers to determine their location (longitude/latitude/altitude) to high precision (within a few meters) using time signals transmitted along a line of sight by radio from satellites. |
| 40 | 3 | COLIN, Tony | Global coverage for each system is generally achieved by a satellite constellation of 20–30 medium Earth orbit (MEO) satellites spread between several orbital planes. The actual systems vary, but use orbital inclinations of >50° and orbital periods of roughly 12 hours._ |
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| 42 | 3 | COLIN, Tony | --- |
| 43 | 3 | COLIN, Tony | |
| 44 | 3 | COLIN, Tony | h2. 3 - Comparison of systems. |
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| 46 | 3 | COLIN, Tony | p=. !31-2.png! |
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| 48 | 3 | COLIN, Tony | p=. !30.png! |
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| 50 | 3 | COLIN, Tony | --- |
| 51 | 3 | COLIN, Tony | |
| 52 | 3 | COLIN, Tony | h2. 4 - Our system : GPS details. |
| 53 | 3 | COLIN, Tony | |
| 54 | 3 | COLIN, Tony | _http://www.gps.gov/systems/gps/space/ |
| 55 | 3 | COLIN, Tony | https://en.wikipedia.org/wiki/Global_Positioning_System_ |
| 56 | 3 | COLIN, Tony | |
| 57 | 3 | COLIN, Tony | h3. a- Space Segment. |
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| 59 | 3 | COLIN, Tony | p=. !26.png! |
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| 61 | 3 | COLIN, Tony | p=. !28-2.gif! |
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| 63 | 3 | COLIN, Tony | h3. b- Ground Control Segment. |
| 64 | 3 | COLIN, Tony | |
| 65 | 3 | COLIN, Tony | Continuously > Track GPS satellites, estimate clock and orbit, keep GPS time, upload data that describes clock & orbit for each satellite |
| 66 | 3 | COLIN, Tony | Infrequently > Command small maneuvers to maintain orbit, small clock corrections, major relocations to compensate any satellite failure |
| 67 | 3 | COLIN, Tony | |
| 68 | 3 | COLIN, Tony | h3. c- Delivery of Navigation messages. |
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| 70 | 3 | COLIN, Tony | Clock & Ephemeris sent by GS to SS, Spread Spectrum ranging signals & navigation data sent by SS to US & GS. |
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| 72 | 3 | COLIN, Tony | h3. d- Signals. |
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| 74 | 5 | COLIN, Tony | p=. !2.png! |
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| 76 | 3 | COLIN, Tony | h3. e- Ranging. |
| 77 | 3 | COLIN, Tony | |
| 78 | 3 | COLIN, Tony | Propagation time : Time of transmission - Time of reception |
| 79 | 3 | COLIN, Tony | Distance between satellite and receiver \approx Propagation time x Speed of light |
| 80 | 3 | COLIN, Tony | |
| 81 | 6 | COLIN, Tony | attachment:"Howitworks 29.pdf" |
| 82 | 3 | COLIN, Tony | |
| 83 | 3 | COLIN, Tony | _In geometry, *trilateration* is the process of determining absolute or relative locations of points by measurement of distances, using the geometry ofcircles, spheres or triangles. :_ |
| 84 | 3 | COLIN, Tony | 1 measurement : 1 sphere of radius D1 centered in Sat1 |
| 85 | 3 | COLIN, Tony | 2 measurements : intersection of 2 spheres (D1, Sat1) (D2, Sat2) = Circle |
| 86 | 3 | COLIN, Tony | 3 measurements : intersection of 3 spheres (D1, Sat1) (D2, Sat3) (D2, Sat3) = 2 points (1 often aberrant) |
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| 88 | 3 | COLIN, Tony | p=. !20.png! |
| 89 | 3 | COLIN, Tony | |
| 90 | 3 | COLIN, Tony | h3. f- GNSS Receivers. |
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| 92 | 3 | COLIN, Tony | p=. !21.png! |
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| 94 | 3 | COLIN, Tony | p=. !22.png! |
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| 96 | 3 | COLIN, Tony | h3. g- GNSS Measurements. |
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| 106 | 3 | COLIN, Tony | *References :* |
| 107 | 3 | COLIN, Tony | *[1]* M. Sahmoudi, Introduction to satellite positioning & multi-sensor navigation, 2016 |
| 108 | 3 | COLIN, Tony | *[2]* K. Borre, D. M. Akos, N. Bertelsen, P. Rinder, S. H. Jensen, A software-defined GPS and GALILEO receiver |
| 109 | 3 | COLIN, Tony | *[3]* https://en.wikipedia.org/wiki/Satellite_navigation |
| 110 | 3 | COLIN, Tony | *[4]* https://en.wikipedia.org/wiki/Global_Positioning_System |
| 111 | 3 | COLIN, Tony | *[5]* http://www.gps.gov/systems/gps/ |