Presented by Rehana Jamal (GIS Expert & Geographer) Dated: Advance Applications of RS/GIS in Geo-Environmental Conservation Subject Lecture-6 M.Phil & P.hd Topic Original GPS Technologies 18 Nov-141

Russian: GLONASS(Global Navigation Satellite system) available to civilian in 2007 European Community: Galilio Positioning System Chinese: Compass Navigation System Indian: Indian Regional Navigation Satellite System United States: NAVSTAR(Navigation Signal Time and Ranging) Global Positioning System Advance GPS Technologies 18 Nov-142

3 Advance GPS Technologies

Definition “A system of satellites, computers, and receivers that is able to determine the latitude and longitude and altitude of a receiver on Earth by calculating the time difference for signals from different satellites to reach the receiver.” NAVSTAR Global Positioning System Global Positioning System (GPS) is a DoD developed, worldwide, satellite-based radio navigation system. 18 Nov-144

GPS project  was worldwide, satellite-based radio navigation system  was developed in 1973  was created by the U.S. Department of Defense (DoD)  run with 24 satellites  became fully operational in 1995 NAVSTAR Global Positioning System 18 Nov-145

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7 Orbital inclination Polar Orbit ° Sunsyncronous Orbit 55 ° Geostationary Orbit 0 °

18 Nov-148 Polar Orbit ° Sunsyncronous Orbit 55 °/60° Geostationary Orbit 0 ° Orbital inclination

18 Nov-149 Polar Orbit °

18 Nov-1410 Sunsyncronous Orbit 55 °/60°

Geostationary / Geosynchronous orbit 0° 18 Nov-1411

18 Nov-1412 Geostationary Orbit 0° Side view

18 Nov-1413

18 Nov-1414 GPS is a Constellation of satellites

18 Nov-1415 Old Orbits 3 Orbits & 8 Satellites New Orbits 6 Orbits & 4 Satellites Satellite Distances of New Orbits 105° 30° 120° 105° Satellites orbit

The constellation of GPS consists of 24 operational satellites. The U.S. Air Force Space Command (AFSC) formally declared the GPS satellite constellation as having met the requirement for Full Operational Capability (FOC) as of July 27, GPS capabilities Two service levels of GPS 1. SPS 2. PP S 18 Nov-1416

1. SPS(Standard Positioning Service) 2. PPS (Precise Positioning Service ) Provided on GPS L1 Frequency having C/A code Horizontal accuracy = 100meters(95%) Vertical accuracy = 156meters (95%) Time transfer accuracy = 340 nanoseconds (95%) Provided on GPS L1 & L2 Frequencies, both having P -code Horizontal accuracy = 22meters(95%) Vertical accuracy = 27.7meters (95%) Time transfer accuracy = 200 nanoseconds (95%) 18 Nov-1417

Figure:GPS signal structure The satellites transmit on two L-band frequencies: L1 = MHz and L2 = MHz. Three pseudo-random noise (PRN) ranging codes are in use. The coarse/acquisition (C/A) code has a MHz chip rate, a period of 1 millisecond (ms) and is used primarily to acquire the P-code. The precision (P) code has a MHz rate, a period of 7 days and is the principal navigation ranging code. The Y-code is used in place of the P-code whenever the anti-spoofing (A-S) mode of operation is activated. Original Design of GPS signals /GPS signal characteristics 18 Nov-1418

Selective Availability A protection technique employed by the DOD to deny full system accuracy to unauthorized users. 18 Nov-1419 A Selective Availability Anti-spoofing Module (SAASM) is used by military Global Positioning System receivers to allow decryption of precision GPS coordinates, while the accuracy of civilian GPS receivers may be reduced by the United States military through Selective Availability.Global Positioning SystemUnited States military Selective Availability

This is a plot of GPS navigational errors through the SA transition prepared by Rob Conley of Overlook Systems for the GPS Support Center in Colorado Springs, Colorado. The GPS errors can be seen diminishing significantly around 0405 UTC (shortly after midnight EDT). The data indicates a circular error of only 2.8 meters and a spherical error of 4.6 meters during the first few hours of SA- free operation. The data was measured using a Trimble SV6 receiver. Selective Availability (SA) was an intentional degradation of public GPS signals implemented for national security reasons. 18 Nov-1420

18 Nov-1421 GPS Structure/GPS Segments

The SPACE segment consists of  24 operational satellites in six orbital planes (four satellites in each plane).  Orbits circular: 20,200 km (10,900 nm)  Inclination angle of 55 degrees  Period :12-hour  The position same at the same sidereal time each day SPACE segment 18 Nov-1422

CONTROL segment The CONTROL segment consists of Five Monitor Stations (Hawaii, Kwajalein, Ascension Island, Diego Garcia, Colorado Springs) Three Ground Antennas, (Ascension Island, Diego Garcia, Kwajalein) Master Control Station (MCS) located at Schriever AFB in Colorado. 18 Nov-1423

The USER segment consists of Antennas and receiver-processors that provide positioning, velocity, and precise timing to the user. USER segment 18 Nov-1424

GPS system time 18 Nov-1425 GPS system time is the atomic time scale implemented by the atomic clocks/Composite Clock (CC) in the GPS ground control stations and GPS satellites themselves GPS time was at 0h on 6 Jan,1980 and since it is not perturbed by leap seconds. The CC or "paper" clock consists of all operational Monitor Station and satellite frequency standards.

Semi-major axis a Defines the size of the orbit. Eccentricity e Defines the shape of the orbit. Inclination i Defines the orientation of the orbit with respect to the Earth's equator. Argument of Perigee Defines where the low point, perigee, of the orbit is with respect to the Earth's surface. Right Ascension of the Ascending Node Defines the location of the ascending and descending orbit locations with respect to the Earth's equatorial plane. True/Mean Anomaly Defines where the satellite is within the orbit with respect to perigee. Orbital Elements Orbital elements are the parameters required to uniquely identify a specific orbit and are used to describe the motion of satellites within an orbit. 18 Nov-1426

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Fig. A scale diagram showing earth and various orbits above it 18 Nov-1428

GPS Block IIIA Lecture to be continued ………till Advance GPS Satellites 18 Nov-1429

Early Delta Flights 18 Nov-1430

18 Nov-1431  “GPS is a system of satellites, computers, and receivers that provides 3 dimensional data.  developed in 1973 by the U.S. Department of Defense (DoD)  Old Orbits Orbits & 8 Satellites  New Orbits Orbits & 4 Satellites  GPS capabilities  Satellite Distances of New Orbits  GPS Structure/GPS Segments  Design of GPS signals /GPS signal characteristics  Selective Availability Summary

References Nov-1432