The document summarizes key aspects of the Global Positioning System (GPS). It describes that GPS is a satellite-based navigation system consisting of 24 satellites orbiting about 12,000 miles above Earth. GPS satellites circle the globe twice a day, transmitting radio signals to GPS receivers, which use the signals to calculate the user's precise location and display it on an electronic map. Possible sources of error include signal reflection, satellite shading, and clock inaccuracies between receiver and satellite clocks.

1. GPS
Global Positioning System
Done by Khudashov Volodimir

2. INTRODUCTION
The Global Positioning System (GPS) is a satellite-based navigation
system made up of a network of 24 satellites placed into orbit.
The first GPS satellite was launched in 1978.
In the year 1980, the government made the
system available for civilian use.
GPS works in any weather conditions, anywhere in the
world, 24 hours a day.

3. THE 24 SATELLITES THAT MAKE UP THE GPS
SPACE SEGMENT ARE ORBITING THE EARTH
ABOUT 12,000 MILES ABOVE US.

4. WHAT'S A GPS SIGNAL?
There are two frequencies of low power radio signals
that GPS satellites transmit.
These are called L1 and L2.
The L1 frequency at 1575.42 MHz in the UHF band is what
comes into play for civilian applications.

5. HOW GLOBAL POSITIONING SYSTEM WORKS?
.
GPS satellites circle the earth twice a day in a very
precise orbit and transmit signal information to
earth.
GPS receivers take this information and use to
calculate the user's exact location.
The receiver can determine the user's position and
display it on the unit's electronic map.

6. POSSIBLE CAUSES OF ERROR
Signal reflection: Here the signal hits and is reflected off
objects like tall buildings, rocks etc.
Satellite Shading: For the signals to work properly the
satellites have to be placed at wide angles from each
other.
Clock errors: The built in clock of the GPS receiver is not
as accurate as the atomic clocks of the satellites and the
slight timing errors leads to corresponding errors in
calculations.

7. SOME GPS DEVICES
GPS Maps Smart Phones TOMTOM
(CARS)

8. Thank you