PRESENTATION BASED ON GPS Introduction To GPS GPS

PRESENTATION BASED ON GPS

Introduction To GPS

• GPS is a spaced based radio positioning system, which provide suitably equipped user with highly accurate position, velocity and time data GPS provide specially coded signals that can be processed in a GPS receiver. n A GPS receiver decodes time signal transmission from multiple satellites and calculated its position. n

GPS system was designed & controlled by US military. n The cost of maintaining the system is approximately US $400 million per year including the replacement of aging satellite. n

Earth Circumference Ø 24, 900 Miles Rotation Ø 1, 038 Miles/Hour Ø 1 Day Cycle

Moon 1/4 Size of the Earth Distance from Earth Ø 239, 000 Miles

The History of GPS Ø Feasibility studies begun in 1960’s. Ø Pentagon appropriates funding in 1973. Ø First satellite launched in 1978. Ø System declared fully operational in April, 1995. Ø Open to the public, 2000.

How does GPS work? n Stations on earth, and a GPS receiver, the distances between each of these points can be calculated. n The distance is calculated based on the amount of time it takes for a radio signal to travel between these points. n Using satellites in the sky, ground allows the GPS receiver to know where you are, in terms of latitude and longitude, on the earth. n The more satellites the GPS can “see”, the more accurate your reading. n The GPS must “see” the satellites, so it does not work well in dense forests, inside caves, underwater, or inside buildings.

GPS Satellites Distance from Earth 12, 000 Miles 2 Orbits in 24 Hours Travel 7, 000 MPH Powered by Solar Energy

Satellites Segments

Three major segment of GPS system n Space n n segment Control segment User segment

Space segment : A space segment contain 24 satellites. n The satellite arranged such that a minimum of four satellite is in view to a user at any time on a world wide basis. n Each satellite transmits signals on two radio frequencies, superimposed on which are navigation and system data. n The satellite orbit in six separate orbital planes. n

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ü 24 satellites in six orbital plane ü 12, 000 miles above Earth ü Orbit twice daily ü At least 4 satellites in view ü Distance from Earth to Moon - 256, 000 miles

ü 4 satellite in each plane ü 20, 200 km altitude 55 degree inclination.

Control Segment The control segment includes a master control station(MCS). n A number of monitor stations, and ground antennas throughout the world. n The master control station, located in Colorado Springs. n Colorado consists of equipment and facilities required for satellite monitoring, tracking, commanding, control, uploading, and navigation message generation. n

Ø Ø Ø Ø Ø User Segment 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.

What does a GPS receiver do? n GPS receiver allows you to pinpoint your location, anywhere in the world, based on latitude and longitude coordinates. n It can tell you in what direction you are heading. n It can show you: n how fast you are going n your altitude n a map to help you arrive at a destination

Signal From One Satellite The receiver is somewhere on this sphere.

Signals From Two Satellites

Three Satellites (2 D Positioning)

Three Dimensional (3 D) Positioning

How GPS Works Ok, you’re lost, you have amnesia, and you have absolutely no idea where you are. You go up to someone, and like a good amnesiac you ask, “Where Am I? ” This person tells you that you are 625 miles from Boise, Idaho. You say, sarcastically, “Wow, that’s some great information. Thanks Buddy. ”

We’re Getting Closer You still have absolutely no idea where you are, so once again you go up to someone and ask, “Where Am I? ” This person tells you that you’re 690 miles from Minneapolis. You just scratch your head, but then you start to remember what you learned in GPS class, and, with the US map in your pocket to guide you, you proceed.

Now We Know! You see a another smiling face and ask “where am I” one more time. This time you get the reply “you are 615 miles from Tucson. The light pops on in your brain. It’s all clear now. You draw three circles extending in the radii of 625 miles from Boise, 690 from Minneapolis, and 615 miles from Tucson. The circles intersect in Denver! Aren’t you glad that you took this class?

GPS by Trilateration GPS Distance D = Speed of Light x Time; or D = CT D

Waypoint Ø Ø Ø A waypoint is based on coordinates entered into a GPS receiver’s memory. It can be either a saved position fix, or user entered coordinates. It can be created for any remote point on earth. It must have a receiver designated code or number, or a user supplied name. Once entered and saved, a waypoint remains unchanged in the receiver’s memory until edited or deleted.

S K N A H T