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Abstract
A vehicle tracking system is an electronic device installed in a vehicle to enable the owner or a third party to track the vehicle's location. Most modern vehicle tracking systems use Global Positioning System (GPS) modules for accurate location of the vehicle. Many systems also combine a communications component such as cellular or satellite transmitters to communicate the vehicle’s location to a remote user. . The GPS satellite system was built and is maintained by government and is available at no cost to civilians. This makes this technology very inexpensive. Vehicle information can be viewed on electronic maps via the Internet or specialized software. The Position coordinates sent by the GPS device will be logged by the µC at periodic intervals. After processing the data, the data will be uploaded to the server via the Internet Connection. The program resident on the server will process the data and map the position on a Google map. The Google map view can be accessed through and other PC’s, thus giving real time positioning of the vehicle. Due to ARM µc we can also guide the driver of vehicle about path followed by him. Now a day’s all the accidents on the Highway are due to consumption of alcohol. This device makes the ignition system smart by adding intelligence to it. The alcohol content of the driver is measured before turning ON the engine. Alcohol sensors are employed in a wide range of applications in the fields of safety, health.
In addition to this we are providing accident switches to the vehicle from
outside, these switches get pressed at the time of accident & inform to nearest hospital & ambulance by predefined message with longitude & latitude coordinates of accident place .Similarly we can send message to police in case of dacoit by pressing emergency switch.
A. Objective
 Exploring GPS based tracking systems.
 Developing Automatic Vehicle Location system using GPS for positioning information and GSM/GPRS for information transmission with following features:
 Acquisition of vehicle’s location information (latitude longitude) after specified time interval.
 Transmission of vehicle’s location and other information (including ignition status, door open/close status) to the monitoring station/Tracking server after specified interval of time.
 Developing a web based software to display all transmitted information to end user along with displaying location of vehicle on a map
GPS WORKING
A GPS receiver module calculates its position by precisely timing the signals sent by GPS satellite.
5.2.1 Trilateration Basics
When people talk about "a GPS," they usually mean a GPS receiver. The Global Positioning System (GPS) is actually a constellation of 27 Earth-orbiting satellites (24 in operation and three extras in case one fails). The U.S. military developed and implemented this satellite network as a military navigation system, but soon opened it up to everybody else. Each of these 3,000- to 4,000-pound solar-powered satellites circles the globe at about 12,000 miles (19,300 km), making two complete rotations every day. The orbits are arranged so that at anytime, anywhere on Earth, there are at least four satellites "visible" in the sky. A GPS receiver's job is to locate four or more of these satellites, figure out the distance to each, and use this information to deduce its own location. This operation is based on a simple mathematical principle called trilateration. Trilateration in three-dimensional space can be a little tricky, so we'll start with an explanation of simple two-dimensional.
5.2.2 2-D Trilateration
Imagine you are some wherein the United States and you are TOTALLY lost – for whatever reason, you have absolutely no clue where you are. You find a friendly local and ask, "Where am I?" He says, "You are 625 miles from Boise, Idaho." This is a nice, hard fact, but it is not particularly useful by itself. You could be anywhere on a circle around Boise that has a radius of 625 miles. You ask somebody else where you are, and she says, "You are 690 miles from Minneapolis, Minnesota." Now you're getting somewhere. If you combine this information with the Boise information, you have two circles that intersect. You now know that you must be at one of these two intersection points, if you are 625 miles from Boise and 690 miles from Minneapolis.
If a third person tells you that you are 615 miles from Tucson, Arizona, you can eliminate one of the possibilities, because the third circle will only intersect with one of these points. You now know exactly where you are -- Denver, Colorado. This same concept works in three-dimensional space, as well, but you're dealing with spheres instead of circles. In the next section, we'll look at this type of trilateration.