18-04-2010, 10:51 PM
Seminar on GPS.ppt (Size: 603 KB / Downloads: 263)
GLOBAL POSITIONING SYSTEM
Why do we need GPS?
The Global Positioning System (GPS) is a space-based global navigation system.
It provides reliable positioning, navigation, and timing services to worldwide users on a continuous basis in all weather, day and night, anywhere on or near the Earth.
On the whole, GPS works efficiently with the help of satellite communication.
Components of the GPS
Space Segment:
The Space Segment is composed of 24 to 32 satellites in Medium earth orbit and also includes the boosters required to launch them into orbit.
Control Segment:
The control segment comprises of 5 stations.
They measure the distances of the overhead satellites every 1.5 seconds and send the corrected data to Master control.
Here the satellite orbit, clock performance and health of the satellite are determined and determines whether repositioning is required.
This information is sent to the three uplink stations
User Segment:
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
Emergence of GPS:
Before the invention of GPS, the device that is used for tracing is a micro tracing device, which is mainly used for tracing the movement of animals(mainly Birds).This device weighs nearly 1 to10 grams, which is fixed with the body of the animal.
How does the GPS work?
Requirements
Triangulation from satellite
Distance measurement through travel time of radio signals
Very accurate timing required
To measure distance the location of the satellite should also be known
Finally delays have to be corrected
Working process
GPS or Global Positioning System is a technology for locating a person or an object in three dimensional spaces anywhere on the Earth or in the surrounding orbit. GPS is a very important invention of our time on account of the many different possibilities it brings.
To understand the working of GPS we should mainly need to know the satellite communication, which includes three main links namely
~>Uplink
~>Downlink
~>Crosslink
Pictorial representation
Triangulation
Position is calculated from distance measurement
Mathematically we need four satellites but three are sufficient by rejecting the ridiculous answer
Measuring Distance
Distance to a satellite is determined by measuring how long a radio signal takes to reach us from the satellite
Assuming the satellite and receiver clocks are sync. The delay of the code in the receiver multiplied by the speed of light gives us the distance
Applications
Defense purpose
Recovery of theft
Tracing objects
In predicting purpose
In heart failure alert system
Unmanned control service (Artificial Intelligence).