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gps
- 1. Global Positioning SystemGlobal Positioning System
- 2. Introduction to GPS GPS is funded by and controlled by the US Department of Defense (DOD). GPS provides specially coded satellite signals that can be processed in a GPS receiver, enabling the receiver to compute position, velocity, and time.
- 3. What is GPS? GPS, which stands for Global Positioning System, is the only system today able to show you your exact position on the Earth anytime, in any weather, anywhere.
- 4. GPS: Global PositioningGPS: Global Positioning SystemSystem 4
- 6. The three parts of GPS are: GPS systems are made up of 3 segments Space Segment (SS) Control Segment (CS) User Segment (US)
- 7. Space SegmentSpace Segment 24 satellites in orbit dedicated to GPS that orbit the Earth in very precise orbits twice a day. 6 satellites are within view of any location at one time. Satellites constantly transmit their location information and time data.
- 8. Control Segment Ground antennas monitor and track the satellites. They also transmit correction information to individual satellites.
- 9. Kwajalein Atoll US Space Command Control Segment Hawaii Ascension Is. Diego Garcia Cape Canaveral Ground AntennaMaster Control Station Monitor Station
- 10. User Segment GPS receivers include a display for showing location and speed information to the user.
- 11. User segmentUser segment GPS antennas & receiver/processorsGPS antennas & receiver/processors PositionPosition VelocityVelocity Precise timingPrecise timing Used byUsed by AircraftAircraft Ground vehiclesGround vehicles ShipsShips IndividualsIndividuals
- 12. Handheld GPS ReceiversHandheld GPS Receivers
- 13. Casio GPS wristwatchCasio GPS wristwatch
- 14. GPS Applications Military: fighters, bombers, detect missiles, weapons, nuclear. Automobiles: show moving maps (highways, buildings) Aviation: for aircraft navigation Marine: Provides precise navigation information to boaters.
- 16. Working Of GPS
- 17. How GPS worksHow GPS works GPS uses satellites as reference points to calculate accurate positions. Each satellite orbits the earth every 12 hours (2 complete rotations every day). This ensures that every point on the Earth will always be in radio contact with at least 4 satellites. Ground stations are used to precisely track each satellite's orbit.
- 18. GPS satellites transmit signals to equipment on the ground. GPS receivers passively receive satellite signals; they do not transmit. GPS operations depend on a very accurate time reference, which is provided by atomic clocks. Each GPS satellite has atomic clocks on board. Each GPS satellite transmits signals that indicates its location and the current time. The signals, moving at the speed of light, arrive at a GPS receiver at slightly different times because some satellites are farther away than others.
- 19. Calculating Distance Velocity x Time = Distance Radio waves travel at the speed of light, roughly 186,000 miles per second (mps) If it took 0.06 seconds to receive a signal transmitted by a satellite floating directly overhead, use this formula to find your distance from the satellite. 186,000 mps x 0.06 seconds = 11,160 miles
- 20. Aircraft Navigation using GPS Civil aircraft typically fly from one waypoint to another. With GPS, an aircraft's computers can be programmed to fly a direct route to a destination. This can save fuel and time GPS also can simplify and improve the method of guiding planes to a safe landing, especially in poor weather. With advanced GPS systems, airplanes can be guided to touchdown even when visibility is poor.
- 21. Using GPS, aircraft can fly the most direct routes between airports
- 22. A GPS receiver in the cockpit provides the pilot with accurate position data and helps him keep the airplane on course.
- 23. Advantages of GPS GPS can provide accurate, continuous, all- weather coverage for aircraft position determination anywhere on the earth. Thus, GPS can serve better air traffic management (ATM) system. GPS can maintain high levels of flight safety GPS can reduce the aircraft delays problem GPS can increase airway capacity. GPS can reduce fuel consumption
- 24. Reduced costs to each individual State while increasing overall benefits to individual States Maintain economies from reduced maintenance and operation of ground-based systems (such as VOR/DME/NDB station) Improved ground and cockpit situational awareness Increased landing capacity for aircraft More efficient, optimized, flexible, and user- preferred route structures
- 25. Time Difference
- 26. GPS Distance D = Speed of Light x Time; or D = CT D
- 27. GPS Limitations Line of Sight Transmissions: Obstructions such as trees, buildings may prevent clear line of sight. Refraction: GPS signal from the satellite doesn’t follow a straight line Signal Interference: Sometimes the signals interfered before they hit the receivers.
- 28. Obstruction
Editor's Notes
- GPS is funded by and controlled by the US Department of Defense (DOD). While there are many thousands of civil users of GPS world-wide, the system was designed for and is operated by the U. S. military. GPS provides specially coded satellite signals that can be processed in a GPS receiver, enabling the receiver to compute position, velocity, and time. Four GPS satellite signals are used to compute positions in three dimensions and the time offset in the receiver clock. Made up of two dozen satellites working in unison are known as a satellite constellation This constellation is currently controlled by the United States Air Force 50th Space Wing It costs about $750 million to manage and maintain the system per year Mainly used for navigation, map-making and surveying GPS Satellite Vehicle Four atomic clocks Three nickel-cadmium batteries Two solar panels Battery charging Power generation 1136 watts S band antenna—satellite control 12 element L band antenna—user communication Block IIF satellite vehicle (fourth generation)
- Feasibility studies begun in 1960’s. Pentagon appropriates funding in 1973. First satellite launched in 1978. System declared fully operational in April, 1995. Open to the public, 2000. System Performance Standard Positioning System 100 meters horizontal accuracy 156 meters vertical accuracy Designed for civilian use No user fee or restrictions Precise Positioning System 22 meters horizontal accuracy 27.7 meters vertical accuracy Designed for military use
- 24 satellites 12,000 miles above Earth Orbit twice daily At least 4 satellites in view Distance from Earth to Moon - 256,000 miles There are quite a number of satellites out there in space. They are used for a wide range of purposes: satellite TV, cellular phones, military purposes and etc. Satellites can also be used by GPS receivers.
- GPS satellites fly in circular orbits at an altitude of 20,200 km and with a period of 12 hours. Powered by solar cells, the satellites continuously orient themselves to point their solar panels toward the sun and their antenna toward the earth. Orbital planes are centered on the Earth Each planes has about 55° tilt relative to Earth's equator in order to cover the polar regions. Each satellite makes two complete orbits each sidereal day. Sidereal - Time it takes for the Earth to turn 360 degrees in its rotation It passes over the same location on Earth once each day. Orbits are designed so that at the very least, six satellites are always within line of sight from any location on the planet. The system consists of a constellation of 24 satellites (with about 6 "spares") that orbit 11,000 nautical miles above Earth’s surface and continuously send signals to ground stations that monitor and control GPS operations. Distance from Earth 12,000 Miles 2 Orbits in 24 Hours Travel 7,000 MPH Powered by Solar Energy
- The master control station, located at Falcon Air Force Base in Colorado Springs, Colorado, is responsible for overall management of the remote monitoring and transmission sites. Six monitor stations are located at Falcon Air Force Base in Colorado, Cape Canaveral, Florida, Hawaii, Ascension Island in the Atlantic Ocean, Diego Garcia Atoll in the Indian Ocean, and Kwajalein Island in the South Pacific Ocean. Each of the monitor stations checks the exact altitude, position, speed, and overall health of the orbiting satellites. The control segment uses measurements collected by the monitor stations to predict the behavior of each satellite's orbit and clock. The prediction data is up-linked, or transmitted, to the satellites for transmission back to the users. The control segment also ensures that the GPS satellite orbits and clocks remain within acceptable limits. A station can track up to 11 satellites at a time. This "check-up" is performed twice a day, by each station, as the satellites complete their journeys around the earth. Variations such as those caused by the gravity of the moon, sun and the pressure of solar radiation, are passed along to the master control station.
- Military. Search and rescue. Disaster relief. Surveying. Marine, aeronautical and terrestrial navigation. Remote controlled vehicle and robot guidance. Satellite positioning and tracking. Shipping. Geographic Information Systems (GIS). Recreation.
- Military GPS user equipment has been integrated into fighters, bombers, tankers, helicopters, ships, submarines, tanks, jeeps, and soldiers' equipment. Military applications of GPS include target designation of cruise missiles and precision-guided weapons (nuclear detectors). For aircraft, GPS provides Continuous, reliable, and accurate positioning information for all phases of flight on a global basis, freely available to all. Safe, flexible, and fuel-efficient routes for airspace service providers and airspace users. Increased safety for surface movement operations made possible by situational awareness. Automobiles are often equipped GPS receivers. They show moving maps and information about your position on the map, speed you are traveling, buildings, highways, exits etc. Some of the market leaders in this technology are Garmin and TomTom, not to mention the built in GPS navigational systems from automotive manufacturers. Marine applications GPS allows access to fast and accurate position, course, and speed information, saving navigators time and fuel through more efficient traffic routing. Provides precise navigation information to boaters. Enhances efficiency and economy for container management in port facilities. Other Applications not mentioned here include Railroad systems Heading information – replacing compasses now that the poles are shifting Weather Prediction Skydiving – taking into account winds, plane and dropzone location Many more!
- A GPS device receives signals from satellites orbiting the earth to triangulate your location, which will be given as a global address. Or, the GPS device can lead you to a previously marked location, much like a compass. A GPS device receives signals from satellites orbiting the earth to triangulate your location, which will be given as a global address. Or, the GPS device can lead you to a previously marked location, much like a compass. A GPS receiver can tell its own position by using the position data of itself, and compares that data with 3 or more GPS satellites. To get the distance to each satellite, the GPS transmits a signal to each satellite. The signal travels at a known speed. The system measures the time delay between the signal transmission and signal reception of the GPS signal. The signals carry information about the satellite’s location. Determines the position of, and distance to, at least three satellites, to reduce error. The receiver computes position using trilateration.
- GPS receivers require an unobstructed view of the sky, so they are used only outdoors and they often do not perform well within forested areas or near tall buildings. Each GPS satellite transmits data that indicates its location and the current time. All GPS satellites synchronize operations so that these repeating signals are transmitted at the same instant. This can be done through TRIANGULATION method. To triangulate, GPS receiver measures distance using the travel time of radio signals.
- One drawback of using radio waves generated on the ground is that you have only two choices: a system that is very accurate but doesn’t cover a wide area; or a system that covers a wide area but is not very accurate The Global Positioning System, or GPS, can show you your exact position on Earth any time, anywhere, in any weather. GPS satellite signals can also be detected by GPS receivers, which calculate their locations anywhere on Earth within less than a meter by determining distances from at least three GPS satellites. No other navigation system has ever been so global or so accurate.
- With air travel expanding throughout the 21st Century, GPS can provide a cornerstone of the future air traffic management (ATM) system that will maintain high levels of safety, while reducing delays and increasing airway capacity. To promote this future ATM system, the FAA's objective is to establish and maintain a satellite-based navigation capability for all phases of flight. Satellite navigation is being widely used by aviators worldwide to overcome many of the deficiencies in today's air traffic infrastructure. With its accurate, continuous, all-weather coverage, satellite navigation offers an initial navigation service that satisfies many user requirements worldwide. Unlike current ground-based equipment, satellite navigation permits accurate aircraft position determination anywhere on or near the surface of the earth.
- The GPS receiver compares the time a signal was transmitted by a satellite with the time it was received. The time difference tells the GPS receiver how far away the satellite is.