Global Positioning System - Importance in Civil Enigineering

Object:
This System provides us with accurate horizontal and vertical measurements and gives us the position of observer in terms of Latitude and Longitude.

Advantages:

1. This system is fast replacing with conventional methods of surveying like Triangulation, Traversing etc.
2. It no longer requires the inter-visibility of station points. The conventional techniques are still required for detail surveying.
3. The horizontal and vertical control can easily be established with the help of GPS.

Instruments:
This system basically requires the receiver which is setup at the point of observation. The second part of the equipment is no of satellites which are 18, launched into 6 different orbits.Each orbit have three satellites with 120º interval. The height of satellite is about 20,000 km with orbiting vilocity of 11hr 58min.
The GPS is controlled from an airforce base in Callifornia (USA).



Procedure:
The GPS position is achieved by the precise measurement of the distance between the satellite and the receiver at an instant of time.
For a three dimensional measurements three or four satellites will be needed depending upon the quality of receiving equipment. It requires highely accurate clocks both in the transmitter and in the receiver to measure the precise distance between them.

Applications:

1. This system gives us the accurate geographic position required for land surveying.
2. It is used for navigation purposes in Aircraft,Ships,Submarines etc.
3. It is now exceedingly used to locate the enemy targets and subsequently hitting them by GPS information guided missiles.
4. For public use simpler version are available for locating the vehicles, the individuals and the parties, in hicking and mountaineering expeditions and other number of applications.