What are the 3 segments of GPS Systems?

3 Segments of GPS


The Control Segment: This part consists of 5 worldwide unmanned base-stations that monitor the satellites to track their exact position in space, and to make sure that they are operating correctly. The stations constantly monitor the orbits of the satellites and use very precise radar to check altitude, position and speed.

The Space Segment: This part consists of satellites, manufactured by Rockwell International, which are launched into space by rockets, from Cape Canaveral, Florida. They are about the size of a car, and weigh about 19,000lbs. Each satellite is in orbit above the earth at an altitude of 11,000 nautical miles (12,660 miles), and takes 12 hours to orbit one time

The User Segment: This part consists of user receivers which are hand-held or, can be placed in a vehicle. All GPS receivers have an almanac programmed into their computer, which tells them where each satellite is at any given moment.

How many NAVSTAR satellites are there?



At the moment there are currently 30 Navstar Satellites in orbit.

What altitude are the GPS satellites?



A satellites alltitude aboive the earth is approximately 20,200 kilometers, or 12,550 miles

What is the Inclination of GPS satellite orbits?




The inclination of the orbit of the GPS satellites is 55 degrees (relative to the earths equator)

What is GPS satellite orbital period?


GPS satellites orbital period is 12 hours or twice a day.

What is the speed of light?



 the constancy and universality of the speed of light is recognized by defining it to be exactly 299,792,458 meters per second

How long does it take GPS satellite signal to reach earth surface?

It takes approximatley 200million ms for the signal to reach earths surface.
How many satellites are required for operation?


a mininum of 4 satellites are required for operation.

What is accuracy of standard positioning service? /precise service?



The accuracy for a standard positioning service is up to about 1000 feet.


What are the two L band frequencies of GPS operation?



The two L band frequencies are L1 (1.57542ghz) and L2 (1.2276ghz).