Survey Methodology

The global positioning (GPS) is a satellite based positioning system operated and controlled by the US Department of Defense by using NAVSTAR satellites (SVs) in space. The US department of Defense Controls the system by using four ground based monitor stations, a master and three up loaded stations. GPS Surveying Requires the simultaneous observation of the same four satellites by at least two GPS receivers.

The Base receiver is located over a known control point for the duration of the survey .The rover receiver is moved to the points that are to be surveyed or stacked out. When the data from these two receivers is combined; the result is a three –dimensional vector between the base and rover.

There are Real-Time techniques & post proceed techniques are used to determine the position of the receiver relative to the base.

This is the most common survey used now days with electronic distance measurement system. A total station allows the surveyor to store all information he needs to establish a setting out and can store all information taken from site as existing features , original ground levels ,road edges , etc.

Also the remote measurements are facilitated by the total station where a direct access is not available. For example the height of street light poles, ground clearance of overhead power lines. Etc.

Dumpy level survey is carried out to determine the vertical reference with the mean sea level or available approved datum precisely .with different survey method the elevation of any required point or area is calculated to a millimeter.