 I am Mr. Shashikant B. Gosavi, Assistant Professor, Department of Civil Engineering, Valtran Institute of Technology, Sulapur, presenting before you the online educational resource on construction and types of total station. The learning outcome of this online educational resource is at the end of this session, learners will be able to compare the construction of different types of total station and learners will also be able to explain different parts of total station. Why total station or why total station is called as total station? Obviously, all of us are familiar with several serving instruments. One of them is leveling, which most of us are familiar. There are dumpy levels, auto level, tilting levels and nowadays even some laser levels have come. Digital levels are also there in the market. Primary aim of the leveling is to establish the vertical control. There are distance measuring instruments right from chains, tapes and nowadays electromagnetic distance measuring instruments are also there. Most often we are interested in measuring the horizontal distance, but till now except EDM, rest of the instruments are not capable of measuring the sloping distance. There is another important application in serving, which is measurement of the angles and there are vertical angle measurements as well as horizontal angle measurements, which we are familiar with in case of the conventional instruments. For this we have used the compasses, we have used the theodolites and recently we are also familiar with some of the instruments which are capable of angles by digital theodolite. Here in total station we will be introduced to another important terminology called as the zenith angle. All of us have also worked in computers and therefore the use of the microprocessor is very much known to all of us. Because the total station is comprising of all these applications embedded in a single instrument it is called as the total station. The elements of the total station primarily consists of the display unit in which whatever is the output that will be visible to you. There is a possibility of the input keys just adjacent to that in the form of the keyboard and then there is also a interconnectivity of this display unit with the microprocessor as well as the other elements such as electronic theodolite and electromagnetic distance measuring instrument. There is another important element in case of the total station is electronic theodolite. As all of us are familiar that in case of the theodolite conventionally we are familiar with the what we call as the vernier theodolites. While in electronic theodolite we are having the mechanism embedded inside the instrument which will be capable of many a times even showing you the digital display. The vernier are no more there. In addition to that one of the very very powerful electromagnetic distance measuring instrument has to be a part of the total station. This EDM will transmit the electromagnetic waves. They will strike some prism or reflector and it will come back to the instrument. The phase difference of the emitting wave and returning wave will be calibrated to give us the distance of the target or the reflector from the instrument station. Of course in addition to this in some of the instrument there are reflector less instruments also. What is meant by that is when we transmit the wave it may strike any object in between whichever is actually targeted by us and from there it will get reflected and it will be received back by the instrument which is capable of capable of sensing how much distance is there from the instrument station to the object. In total station microprocessor is there and therefore we can have several computational functions embedded into it. It works like a computer. It can memorize the data. It can of course allow us to use several softwares and the functions which will give us a lot of capabilities similar to that of the computers. This is one of the classical total station which is in front of you. This is a lycomic instrument. As you can see over here there is an eyepiece adjacent to which a focusing screw is also there and from the opposite side you can have a transmission of the electromagnetic wave which will be received back by the instrument and this is how the instrument works. The rotation of this particular part is also possible with the help of which we can even find out the vertical distances. The classification of the total station is primarily in the form of DOS based. All of you are familiar that this is of course age old technology wherein DOS functioning requires you to have possibly some pages and on each of the page certain functions are there. This is relatively inconvenient but of course cost effective. There is window-based instrument nowadays available into the market. In the window-based instrument we can get a view exactly similar to what we can actually get on a computer screen in which window environment is there. There are these kind of instruments which are little bit costlier as compared to DOS based instrument. Most often these will be coming at a cost of around 1 lakh more than the DOS based instrument. The other classification of the total station which is available is robotic total station. In robotic total station you don't need a operator with the instrument. A person with the reflector whosoever is moving on to the field is automatically sensed by the instrument and accordingly the line of sight will be directed, autofocus will happen and whatever is the reading that will be automatically gathered and stored into the instrument. There are GPS enabled instrument nowadays. I mean along with the total station you can have a global positioning system available into the instrument. As all of us are aware that working with the GPS is of course better as compared to that of the total station but then GPS sometimes does not work when we are going into dense forest or when we are going inside a tunnel and therefore in those situations you may find it convenient to have the compatibility of using GPS as well as total station as and when needed. This is a classical sketch of total station and its type. As you can see over here we do have a knob which is capable of measurement to any surface up to 500 meter to 1000 meter we can do that. Over here based in class laser measurement with pin point technology is made available with this specific variety of the Leica. Ambient light sensors are also available. Atomatic controls and display buttons, illuminations happen that means when you are working inside a tunnel or when you are working in a bright sunlight you can easily find the change into the reflection on the display window. Long lasting batteries are there, color screen is there and software on board is there. This is conventionally the tryback along with the foot screws. Here as you can see there is a plummet and on this particular side you can see the horizontal clamp, horizontal tangent screw. This is another example of construction of the total station. It primarily consists of an instrument, there is a reflector and there are some instruments wherein reflector less technologies are also there. The instrument primarily consists of a tryback as I said on the top of which you may find a small bubble tube, circular bubble tube for initial leveling. For the centering we do have a laser beam or many a times optical plummets are available, pin point accuracy has to be there in case of this entry. Then we do have the battery which can be provided into the instrument. One has to make sure that the battery is fully charged and then we do have the capability of transferring the data through the small maybe card, memory card or you can transfer it through the Bluetooth or you can transfer it even through the USB. Then we do have horizontal clamp, we do have vertical clamp, we also have a focusing screw on IPS end and on the opposite side objective end is there. There are guides for the person who is moving on to the field with reflector to confirm whether his position is compatible with the position of the line of sight of the instrument. There is a target which is also called as the reflector, there are several types of reflectors that you are capable of, I mean there are speakers, small reflectors are there and big reflector which can be supported with the supporting rods are also there. This is a specific information about how the prism or reflector is there, there is a holder. This actually is the part through which the reflection happens which is called as the prism and then there is adapter and there is a try back. We do have to pause here and respond to this particular question. The answers to the question are horizontal distance can be calculated with the formula s and z and in total station the vertical angle 0 degree is in zenith direction, zenith is vertically upwards as compared to the instrument. I have used these references while preparing this online educational resource. Thank you very much, one and all.