29-01-2013, 09:49 AM
PRESENTATION ON GPS Based Tracking System
Tracking System.pptx (Size: 831.67 KB / Downloads: 22)
Overview
GPS stands for Global Positioning System.
It is a network of 24 satellites.
First developed by the US Department of Defense in 1978 for military purpose only.
GPS is known as NAVSTAR –Navigational Satellite Timing And Ranging Global Positioning System.
Global Positioning Systems (GPS) is a form of Global Navigation Satellite System (GNSS)
Consists of 24 GPS satellites MEO orbit( about distance of 20,200kms from the surface of the earth.)
Made up of two dozen satellites working in simultaneously are known as a satellite constellation.
This constellation is currently controlled by the United States-Department of Defence.
Beginning of GPS
In 1960s the US-Navy developed TRANSIT to track their fleet of nuclear submarines.
The problem with TRANSIT was it had low accuracy and was not available 24 hours a day.
During this time the US- Air Force also created a system to accurately locate vehicles on land or in the air.
GPS System Overview
The total GPS configuration is comprised of three distinct segments.
1- Space segment- Satellites orbiting the Earth
2- Control segment- Monitoring Stations and Ground Antennas.
3- User segment – Anybody that receives and uses the GPS signal.
Space Segment
GPS satellites fly in circular orbits at an altitude of 20,200 km and with a period of 12 hours.
Each satellite makes two complete revolution around earth in single day.
That means each satellite passes over the same location twice each day.
Control Segment
Six monitor stations are located in different part of world.
Each of the monitor stations checks the exact altitude, position, speed, and overall health of the orbiting satellites.
The control segment uses measurements collected by the monitor stations to predict the behavior of each satellite.
The control segment also tells about the orbits of GPS satellite .
Trilateration
GPS uses a process called trilateration to determine a precise location.
Trilateration is the process of measuring the distance from at least three satellites to determine a location on earth.
Three satellites calculate 2D position (Latitude and Longitude)
Four or more satellites calculate 3D position (Latitude, Longitude, and Altitude)