1. 2 GPS concepts By Mahmoud El Mewafi Mmewafi1@ excite.com Professor of Surveying and Geodesy, Public Works Dept., Faculty of Engineering, Mansoura University, Egypt. Tel 002 0127440767
5. Three Segments of the GPS Control Segment Space Segment User Segment Monitor Stations Ground Antennas Master Station
6. Control Segment Kwajalein Atoll US Space Command Hawaii Ascension Is. Diego Garcia Cape Canaveral Ground Antenna Master Control Station Monitor Station
12. Position is Based on Time T + 3 Distance between satellite and receiver = “3 times the speed of light” T Signal leaves satellite at time “T” Signal is picked up by the receiver at time “T + 3”
48. Real Time Differential GPS True coordinates = x +0, y +0 Correction = x -5, y +3 DGPS correction = x +(30-5) and y +(60+3) True coordinates = x +25, y +63 DGPS Site x +30, y +60 x +5, y -3 x -5, y +3 DGPS Receiver Receiver
49. Differential Correction 2 10m 10m Base Station (w/known coordinates) Receiver (unknown Location) GPS Receiver Estimated Location Differentially Corrected Estimated Position GPS Estimated Location Actual (Known) Position
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54. Wide Area Augmentation System Geostationary WAAS satellites GPS Constellation WAAS Control Station (West Coast) Local Area System (LAAS) WAAS Control Station (East Coast)
55. How good is WAAS? With Selective Availability set to zero, and under ideal conditions, a GPS receiver without WAAS can achieve fifteen meter accuracy most of the time.* Under ideal conditions a WAAS equipped GPS receiver can achieve three meter accuracy 95% of the time.* * Precision depends on good satellite geometry, open sky view, and no user induced errors. + - 3 meters +-15 meters
76. Garmin’s cheapest receivers Garmin’s iQue 3600 PDA: http://www.garmin.com/products/iQue3600/ Garmin’s Forerunner 201: A watch that uses GPS to determine current speed, average speed, exact distance traveled, etc. ( ) Basic features also available in the Forerunner 101 ($115). http://www.garmin.com/products/forerunner201/
80. Garmin GPSmap60-C Main Screens Setup By default, the GPSmap60 will record a Track (line feature) whenever the unit is turned on. Map (GoTo) Profiles
81. Bluetooth GPS Receivers Teletype’s Mini-bluetooth GPS receiver ($175) http://www.mightygps.com/Manufacturer/minibluetooth.htm Teletype’s USB GPS receiver for Laptops ($170) http://www.teletype.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=1250&Category_Code=
82. HP’s Ipaqs and other PDAs with GPS software Hewlett-Packard’s new iPAQ h1945 PDA Now comes equipped with a hp GPS receiver and navigation system ($500) http://www.shopping.hp.com/cgi-bin/hpdirect/shopping/scripts/product_detail/product_detail_view.jsp?BV_SessionID=@@@@0280349227.1102102313@@@@&BV_EngineID=ccckadddfdjlkdgcfngcfkmdflldfgg.0&landing=null&category=handhelds&subcat1=classic_performance&product_code=PF527A%23ABA&catLevel=3 Garmin’s iQue 3600 PDA: http://www.garmin.com/products/iQue3600/
84. GPS – Ellipsoid - Datum GPS uses the WGS84 (World Geodetic System of 1984) as mathematical surface (model) of the earth Elevations are referenced to Height Above Ellipsoid (HAE)
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87. Lat: 40 N Lo: 20 W 60 N 40 N 20 N 20 S 40 S 60 S Equator Prime Meridian 20 W 20 E Lat: 40 00’.00N Lo: 020 00’.00W Lat: 40 00’.00S Lo: 020 00’.00W Every place on earth has a unique location 180 Lo approx. International Date Line o o o O o o o o o o o o o o o
88. 60 04’ .20” N 149 26’.10” W o o 60 o 05’ 149 30’W o 20’
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90. By Mahmoud El Mewafi Mmewafi1@ excite.com Professor of surveting and Geodesy, Public Works Dept., Faculty of Engineering, Mansoura University, Egypt 6 Datum Transformations
91. سطوح المقارنة لكل من الكرة الأرضية ونظام الجي بي اس وعملية تحويل القياسات بينهما Sat. 2 Receiver X Z Y (0, 0, 0) WGS-84 Local Sat. 3 Sat. 1 Sat. 4
Lo 180 is approximately the International Date Line. Except where it is drawn to exclude or include bodies of land. It is drawn west of Alaska so all of Alaska has the same calendar date
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