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The Total Station (TST) is one of the widely used electronic or optical instrument in modern saving. It has been used by many people such as archaeologists (to record excavations) police,(crime scene investigations or private accidents), insurance companies and other numerous surveying applications. If you examine the total station, you will notice that its an electronic theodolite (transit type) coupled with an electronic distance meter (EDM) which can be used for distance measurement of particular land area. There are many TST models available in the market. For example, certain TST models have internal electronic data storage facility which can easily record horizontal and vertical distances, horizontal and vertical angle measurements. Similarly, some models have hand held, computerized external data collectors which can record data on the field. Depending on the sophistication of the model the price of TST instruments vary from low price to very high price. Using TST, usually, distances and angles are measured (reference to the total station) to points under survey, and the corresponding coordinates (X, Y, and Z or north, east and elevation) of the surveyed points are derived (reference to the total station position) using trigonometry or triangulation methods. Also, the total station works on line of sight observations. Thus it has to be set up over an established point or with line of sight to two or several known points. The main important attribute of TST is that it can be combined with a computer. In other words, data can be transfered from the TST to a computer and later using the appropriate application software the results could be analyzed and generated and corresponding map of the surveyed location could be developed More sophisticated TST has Global Navigational Satellite System (GNSS or GPS) which can measure very accurately (few meters) the latitude, longitude and altitude of given location or of a point. The advantage is having GNSS is, it does not require line of sight measuring points. However, the GNSS has poor accuracy in measuring along vertical axis without long occupation periods. Whereas TST allows high precision measurements along the vertical axis. Hence, combining both these technologies (TST & GNSS or GPS), much faster and accurate data can be collected from wide survey area. The latest TST instruments measure angles using electro-optical scanning facility incorporated in it. For example, the extremely precise digital bar-codes etched on rotating glass cylinders or discs have been provided in the TST instrument. These types of highly sophisticated and high quality total stations have the capability of measuring angles up to 0.5 arc-second accuracy when compared with inexpensive total stations that can usually measure angles up to an accuracy of 5 or 10 arc-seconds. TST uses modulated microwave or infrared carrier signal ( emitted by a small solid-state emitter) sent along the instrument's optical path, and reflected by a prism reflector kept at the point under survey. The returning signal is received by the onboard computer of the TST and processed to determine the distance of that particular point. Most of TST instruments can measure distance up to accuracy of 3 millimeters or one-thousandth of a feet. The TST has revolutionized the entire land surveying with accuracy, speed, and convenience. Similarly, with the combination of satellite technology, it can be used for more precision surveys covering wide areas.
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Land Surveys Pty Ltd are licensed surveyors and provide a complete array of surveying services in Perth & Karratha, Western Australia.
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