Introduction to GPS

The Global Positioning System (GPS) is a satellite based navigation system. The Global Positioning System (GPS) is a location system based on a constellation of about 24 satellites orbiting the earth at altitudes of approximately 11,000 to 12,000miles. The concept of GPS was introduced by united states department of defense(DOD).

What is GPS?What is GPS?

• GPS is the only system today able show your exact position on the earth any time, in any weather, any where ground stations, located world wide, continuously monitor them.

• Also known as NAVSTAR ( Navigation Satellite Timing and Ranging Global positioning system) provides instantaneous position, velocity and time information.

1969- Defense Navigation Satellite system (DNSS) formed.

1973- NAVASTAR Global Positioning System Developed.

1978- First 4 Satellites launched.1993—24th satellite launched.1995—full operational capability.May 2000—Military accuracy available to all users.

History of GPS

SATELLITES IN SPACE

GROUND CONTROL STATIONS

RECEIVERS

 

Elements Of GPS

Operational GPS Structure

 SPACE SEGMENT

CONTROL SEGMENT

USER SEGMENT

Space segment •24 GPS space vehicles satellite (SV).•Satellites orbit the earth in 12hr.•There are six orbital planes with nominally four SVs in each.•This constellation provides 5 to 8 SVs from any point on the earth.

• The control segment consist of tracking stations located around the world.•The GPS control segment called the operational control system ,includes all fixed locations ground based monitor stations located throughout the world.

Control segment

User segment •The GPS user segment consist of GPS receivers and user community.

•The GPS receivers coverts SV signals into position, velocity and time estimates.

•Four satellites required to compute the four dimensions of x,y,z(position) and time.

Working of GPSThe GPS system works by determining how long it takes a radio signal transmitted from a satellite to reach a land based receiver and then, using time to calculate distances between the satellite and earth station receiver.

The distance between the satellite and receiver the mathematical relationship.

Distance =velocity *time.

Advantages of GPS-Fast speed .

-Leads u in right direction .

-Helps improve mapping skills.

-Makes navigation easier .

-Has panic buttons built in .

-You can be found easier if in danger or in accident .

Disadvantages of GPSPeople focus on GPS more than road accident.

Needs good care and handling.

Required External power.

Needs batteries (handheld ones).

Services:

Standard Positioning Service

Precise Position Service

Differential Global Positioning System

Standard Positioning Service

Civil worldwide use the SPS without charge or restrictions.

Most of the receivers are capable of receiving the information's .

100m Horizontal accuracy.156m Vertical accuracy.340 nanoseconds time accuracy.

Precise Position Service

Authorized users with cryptographic equipment and keys and specially equipped receivers use PPS.

PPS is highly accurate military positioning, velocity and timing service which will be available on a continuous, worldwide basis to users.

22m horizontal accuracy.27.7m Vertical accuracy.200 nanosecond time accuracy.

It is used to correct bias errors at one location with measured bias errors at a known position.

DGPS removes common mode errors common to both reference and remote receiver.

DGPS accuracy of 1-10m.

DGPS

RS_Vis_14

Application of GPS Technology

Positioning

Navigation system

Military purpose Time synchronization

Tracking

Satellite Geometry :

Propagation Delay Internal Clock Errors :

Multipath :

Limitations of GPS

Global positioning Satellite

GPS satellites orbit at a height of about12,000 miles (19,300 km) and orbit theearth once every 12 hours.

About 24 GPS satellites orbit the earth every12 hours.

Conclusion

The technology of the Global Positioning System is allowing for huge changes in society. The applications using GPS are constantly growing. The cost of the receivers is dropping while at the same time the accuracy of the system is improving. This affects everyone with things such as faster Internet speed and safer plane landings.

more reliable and accurate measurements.

less costly to corporations - since the error removing equipment will no longer be needed.

more affordable and accessible to consumers.

greater incentive for the development of new uses.

THANK THANK YOU ONE & YOU ONE &

ALLALL