NEW SURVEYING INSTRUMENTS

NEW SURVEYING INSTRUMENTS

New surveying instruments

New surveying instruments latest technology on the market is the GPS Total Station. This Global Positioning System, originally developed for the military, uses signals from various US navigational satellites in space to gather information about location, elevation and time anywhere in the world. Surveying instruments with GPS provide three-dimensional data and are faster and more accurate than previous devices as well as being able to function in any kind of weather. They are of course more expensive than a normal Total Station and sometimes the signals received from the satellites can be distorted if the reception in a particular area is not good or if the signals hit off skyscrapers or similar buildings.

• The DGPS —

The DGPS — Differential Global Positioning System, improves the GPS with higher accuracy by using a network of fixed ground-based reference stations to calculate the difference between the positions indicated by the satellites, at least four, and the known fixed positions. When this correction system is working at its best, it can improve the normal accuracy obtained by GPS, which is usually within 1 5 metres to I O cm. Apart from being more accurate, the data obtained from a DGPS is available 24 hours a day, can be used worldwide and provides 3D survey results in real time. In addition, it is not affected by cloud cover.

RTK —

• RTK — Real Time Kinematics is another method used to achieve precise positioning. It uses two GPS receivers at the same time. "The user needs to be near a reference station, which acts as a control point, and then the signal received from the satellites is corrected and transmitted to a second mobile unit for data collection. "This is a technique commonly used in surveying because of its high precision in controlled environments. -The RTK technique can be used for distances of up to 10 or 20 km.

Laser scanners

• They are also now widely used in surveying. Laser scanning is a relatively new technology and has been used as a precise survey instrument only since 1998. It is now commonly used in industry as it very accurate measurements in environments. It is particularly useful in architecture when designing the inside of buildings. The scan can be set up at various positions inside a room or a building in order to make a complete 3D model of the space available. "These drawings can then be used to create 2D architectural drawings, 3D computer models, and final survey documents. Despite drones (unmanned aircraft systems) have been on the market for some time, until now they have not been used much in surveying, but things are about to change. With the latest drone models that are now more practical, less expensive and more lightweight, drones will soon become an integral part of surveying.

Multiple Choice

The army were the first to use GPS. projects.

• true

• false

Multiple Choice

Bad weather can affect the performance of the GPS.

• true

• false

Multiple Choice

Signals received from the GPS are not affected by built-up areas.

• true

• false

Multiple Choice

If it is cloudy, the DGPS doesn't work well.

• true

• false

Multiple Choice

'The DGPS provides information with a 24 hour time lapse.

• true

• false

Multiple Choice

The RTK technique cannot be used for distances over 20 km

• true

• false

Multiple Choice

Laser scanning is very useful for interior design projects.

• true

• false