What is a Total Station?
What is Total Station?
Total station is an advanced surveying instrument that is used to measure horizontal and vertical angles as well as distances of an object relative to the instrument. It consists of an Electromagnetic Distance Measuring Instrument, an electronic theodolite, a microprocessor, an electronic data collector and a storage system.
Features of Total Station
Total station is an advanced surveying instrument that is well-equipped with a range of features. It offers precise measurements of horizontal and vertical angles as well as sloping distances of an object relative to the instrument. It is equipped with a microprocessor, an electronic data collector and a storage system that enables efficient data collection and analysis.
Benefits of Total Station
Total station is an extremely useful tool for surveyors. It can provide accurate measurements of angles and distances with minimal human intervention. It is also equipped with a microprocessor, an electronic data collector and a storage system that can be used to store and analyze large amounts of data. This helps surveyors to save time and money.
Capability of a Total Station
Total Station: A Practical, Portable Instrument
Total station is a practical and portable instrument used for surveying and measuring applications. It is a compact instrument weighing 50 to 55 N, making it easy for a person to carry it to the field. Total stations with different accuracy levels in angle measurement and different ranges of measurements are available in the market. One such instrument is manufactured by SOKKIA Co. Ltd. Tokyo, Japan, as illustrated in the figure below.
Processing Data Collected with a Total Station
The microprocessor unit in a total station processes the data collected to compute the average of multiple angles measured, the average of multiple distances measured, the horizontal distance, the distance between any two points, the elevation of objects, and all the three coordinates of the observed points. The data collected and processed in a total station can then be downloaded to computers for further processing.
Fig: Parts of total station
Important Operations of Total Station
Distance Measurement
WHAT IS ELECTRONIC DISTANCE MEASURING (EDM) INSTRUMENT?
Electronic Distance Measuring (EDM) instrument is a key component of total station, which is used in surveying and engineering. It is capable of measuring distances up to 4.2 km with an accuracy of 5 to 10 mm per km. Additionally, EDM instruments are also equipped with an automatic target recognizer, which allows for the measurement of sloping distances between the instrument and the object.
RANGE OF EDM INSTRUMENT
The range of an EDM instrument is between 2.8 km to 4.2 km. This is an important factor to consider when choosing an EDM instrument for a particular application.
ACCURACY OF EDM INSTRUMENT
The accuracy of measurement of an EDM instrument varies from 5 mm to 10 mm per km. This is necessary for precise and accurate measurements when surveying and engineering.
AUTOMATIC TARGET RECOGNIZER
An EDM instrument is equipped with an automatic target recognizer, which allows for the measurement of sloping distances from the instrument to the object. This is an important feature for surveying and engineering applications.
Angle Measurements
What is an Electronic Theodolite?
An electronic theodolite is a component of a total station and is used to measure both vertical and horizontal angles. It is typically used in surveying and engineering applications to measure angles between two points with an accuracy of 2 to 6 seconds.
How is an Electronic Theodolite Used?
When measuring a horizontal angle, any convenient direction can be taken as the reference direction. When measuring a vertical angle, the vertical, upward direction (zenith) is taken as the reference direction. The electronic theodolite part of the total station is used to measure both horizontal and vertical angles.
What is the Accuracy of an Electronic Theodolite?
The accuracy of angle measurement for an electronic theodolite can range from 2 to 6 seconds. This makes it suitable for a variety of surveying and engineering applications, as it can provide highly accurate measurements of angles between two points.
Data Processing
Microprocessor Averaging
This instrument is equipped with a built-in microprocessor which averages multiple observations. By using the slope distance, vertical and horizontal angles, as well as the height of the instrument’s axis and the targets, the microprocessor is able to calculate the horizontal distance and X, Y, Z coordinates. Additionally, the processor is capable of applying temperature and pressure corrections to the measurements, as long as the atmospheric temperature and pressures are provided.
Temperature and Pressure Corrections
The microprocessor in this instrument is able to apply temperature and pressure corrections to the measurements, provided that the atmospheric temperature and pressure are supplied. This helps to ensure more accurate readings by taking into account external environmental factors that could affect the readings.
Display
Electronic Display Unit:
An electronic display unit is a device that is capable of displaying various data when its keys are pressed. It can be used to display horizontal and vertical distances, horizontal and vertical angles, differences in elevations of two observed points and all the three coordinates of the observed points.
Horizontal and Vertical Distances:
The electronic display unit is able to display horizontal and vertical distances between two points. This can be used to calculate the exact distance between two points in a certain area or environment.
Horizontal and Vertical Angles:
The electronic display unit is also capable of displaying horizontal and vertical angles. This is useful in determining the angles between two points in a certain area or environment.
Difference in Elevations:
The electronic display unit is also able to display the difference in elevations of two observed points. This can be used to calculate the height difference between two points in a certain area or environment.
Coordinates of Observed Points:
Finally, the electronic display unit is able to display the three coordinates of the observed points. This is useful in determining the exact location of a point in a certain area or environment.
Electronic Book
Electronic Note Books for Storing Point Data
Point data can be stored in an electronic note book (e.g. compact disc). These note books have a capacity of 2000 to 4000 points of data. The data stored in the note book can be unloaded to a computer for reuse.
Capacity of Electronic Note Books
The capacity of an electronic note book varies from 2000 points to 4000 points of data. This gives surveyors the ability to store a large amount of data in a small, compact device.
Transferring Data
Surveyors can transfer the data stored in an electronic note book to a computer. This data can then be reused or analysed. The note book can then be reused to store more data.
Uses of Total Station
- Mounting and Levelling the Total Station Instrument
Heading: Mounting and Levelling a Total Station Instrument
The total station instrument is mounted on a tripod and levelled by operating levelling screws. Within a small range, the instrument can adjust itself to be level. The vertical and horizontal reference directions are then indexed using onboard keys. Units for distance, temperature and pressure can also be set (FPS or SI). - Selecting the Measurement Mode
Heading: Selecting a Measurement Mode on a Total Station Instrument
The surveyor can select a measurement mode such as fine, coarse, single or repeated. When a target is sighted, the horizontal and vertical angles, as well as the sloping distances, are measured and recorded along with the point number by pressing the appropriate keys. - Recording Heights
Heading: Recording Heights with a Total Station Instrument
The heights of the instrument and targets can be keyed in after measuring them with tapes. The processor then computes various information about the point which is displayed on the screen and stored in the electronic notebook. - Downloading Data
Heading: Downloading Data from a Total Station Instrument
At the end of the day or whenever the electronic notebook is full, the stored information is downloaded to computers. This point data can be used for further processing with software like AutoCAD, Auto Civil, and Auto Plotter. These programs can be used for plotting contours at any specified interval and for plotting cross-sections along any specified line.
Advantages of Using Total Stations
Advantages of Using Total Station for Surveying
Total station surveying is an advanced surveying technique that provides many benefits over conventional surveying instruments. It offers faster field work, higher accuracy of measurements, and eliminates manual errors in reading and recording. Additionally, total station surveying can quickly and accurately calculate coordinates, and can be used to make maps, plot contours and cross-sections, and change contour intervals and scales.
Checking the Working Condition of Total Station Instruments
Before using total station instruments, surveyors should check the working condition of their instruments. This can be done by locating a set of standard points near the survey office, and then observing these points from the specified instrument station. By doing this, surveyors can ensure that their total station instruments are in good working condition before taking them out for field work.