The Global Positioning System (GPS) is a satellite-based navigation system developed by the U.S. Department of Defense, consisting of 24 satellites in orbit and becoming fully operational in 1994. GPS is essential for various applications such as navigation, surveying, and emergency services, providing precise location data through a receiver that calculates distances from multiple satellites. The system incurs about $750 million in annual maintenance costs and offers free, reliable, and all-weather services to unlimited users.

2. A very precise positioning system
Developed and maintained by the US
Department of Defense (DOD)
* 24 satellites
* 20,200 km high orbit
Satellite based

3.  Official name of GPS is Navigational Satellite Timing
And Ranging Global Positioning System (NAVSTAR
GPS)
 It costs about $750 million to manage and maintain the
system per year
 Mainly used for navigation, map-making and surveying
 The GPS project was developed in 1973 to overcome the
limitations of previous navigation systems
 It became fully operational in 1994. Roger L. Easton is
generally credited as its inventor.

4. 1.Space
segment
2.Control
segment
3.User
segment

5. A
constellation
of 24
satellites

6. Kwajalein Atoll
US Space Command
Hawai
i
Ascension Is.
Diego Garcia
Cape Canaveral
Ground AntennaMaster Control Station Monitor Station

7.  It consists of receivers that
decode the signals from the
satellites.
 The receiver performs
following tasks:
 Selecting one or more
satellites
 Acquiring GPS signals
 Measuring and tracking
 Recovering navigation
data

8.  Free
 Precise
 Reliable
 All weather
 Anytime and anywhere
 Unlimited user capacity
almost

9.  Uses measurements from 4+ satellites
Distance = travel time x speed of light

10.  The distance (x)
from one satellite
tells us we're
located
somewhere on
the surface of an
imaginary sphere
centered on that
satellite with a
radius of x.

11.  Distance
measurements
from two
satellites limits
our location to
the
intersection of
two spheres,
which is a
circle.

12.  A third
measurement
narrows our
location to
just two
points.

13. A fourth
measurement
determines
which point is
our true
location

14.  Each satellite transmits its own
unique code
 Two frequencies used
L1 Carrier 1.57542 GHz
L2 Carrier 1.22760 GHz
 Codes
CA Code use L1 (civilian code)
P (Y) Code use L1 & L2 (military
code)

15.  Many factors can affect the accuracy of GPS
data. Accuracy can range from 1 centimeter to
over 40 meters
significant parameter:-
•Number of visible
satellites
•Satellite Geometry
•Receiver Errors
•Multipath
•Satellite Clock Errors
•Time spent on
measurement
•Atmospheric Effects
•Operator knowledge
and awareness

17. Position dilution of precision
Good PDOP Poor PDOP

18.  in automobiles
 In farmland
 Disaster
relief/emergency
services
 GPS Aircraft Tracking
 Robotics
 Missile and projectile
guidance
 Target tracking