Principle of edm in surveying

The distance measured by edm is more precise than measured with chain or tape. Electronic distance measurement edm is a method of determining the length between two points using electromagnetic waves. By constructing a series of triangles adjacent to one another, a surveyor can obtain other distances and angles that would. Principles and methods of surveying in civil engineering. Total stations use the principle of a theodolite and combine it with electronic distance measurement.

Surveying theory and practice by davis, foote, anderson, and mikhail. Types of electronic distance measurement instrument. The electrode can be a either a wire wire electrical discharge machining or wedm, or the negative of the engraving to be machined into the workpiece plunge edm. The instrument sends out a beam of light or high frequency microwaves from one end of line to be measured, and directs it towards the far end of the line. Then the following equation used to measure the distance, distance velocity x time. The typical edm today uses the electrooptical principle. Electrical discharge machining is a machining method primarily used for hard metals or those that would be very difficult to machine with traditional techniques. Normally these used to measure long distances within. Inspecting the edm of the total station 23 instrument errors in the total station 24 simple surveying tasks 26 aligning from the midpoint 26 measuring slopes 27 measuring rightangles 28 applications programs 29 calculating areas 29 staking out 30 remote heights 31 tie distances 32 freestation surveys 33 the applications programs available 34. There are many ways to measure distances by electronic means. We will limit discussion to electrooptical em instruments since the majority of edms and total stations employ that em type. The principle of the measurement device in edm, which is currently used in a total station and used along with electronicoptic theodolites, is that it calculates the distance by measuring the phase shift during the radiated electromagnetic wave such as an infrared light or laser light or microwave. The surveying equipment functions with the help of micro waves come under this category. Engineering surveying involves the use of optical instruments and equipment in collecting data for the preparation of drawings and in setting out structures or features during a construction project.

There are three basic observables which are measured or recorded within surveying. It is essential to know the fundamental principle behind edm to work with it. Electromagnetic distance measurement edm definition the electronic distance measurement instrument edm is a relatively new development in the field of surveying. Large, trimble integrated surveying group, westminster, colorado, usa the latest technology to revolutionize the surveying industry is direct reflex measurement, electromagnetic distance measurement without cooperative targets or prisms. Chain surveying requires chain, tape and ranging rods. Generally speaking, however, the principle characteristics of electrical discharge machining should give you a sense of whether edm is a good fit for your application. Edm instruments used as a modular component in modern total stations also work under the same principle of. Four basic principles will be presented although only one will be discussed in greater depth. Edm is a surveying instrument for measuring distance electronically between two points through electromagnetic waves. This implies a precise control surveying as the first consideration followed by subsidiary detail surveying. Surveying principles and methods in civil engineering surveying is the process of determining relative positions of different objects on the surface of the earth by measuring horizontal distances between them and preparing a map to any suitable scale. Principles and practice of land surveying sample examination george m. Working from whole to part is done in surveying in order to ensure that errors and mistakes of one portion do not affect the remaining portion.

Principles and methods of surveying in civil engineering projects. Electrical discharge machining process works on the basic principle of spark generation and metal removed by spark erosion. Direct reflex edm technology for the surveyor and civil engineer r. Apr 17, 2018 edm stands for electronic distance measurement. Edm is a surveying instrument used to measure the distance electronically. The internal mechanism is in the same way an edm works with a laser and a sensor. Here the electronic distance measuring equipment and a reflector are necessary to carry out the survey. It is also used by archaeologists to record excavations as well as by police, crime scene investigators, private accident reconstructionists and insurance companies to take measurements of scenes. It is the method of land surveying in which only linear measurements are made.

Direct reflex edm technology for the surveyor and civil. Electronic distance measuring method edm basic civil. Surveying, defined surveying can be defined as 1 the science and art of making all essential measurements in space to determine the relative positions and points andor physical and cultural details above, on, or beneath the earths surface and to depict them in usable form, or to establish the. The principle of chain surveying is triangulation i. Using devices like theodolites, total stations and other surveying equipment. This edm deals with the principles and procedures of separate electronic distance measuring device edm instruments that are mountable with opticelectronic theodolites. The first generation of electromagnetic equipment was very precise for measuring long.

Principles and practice of land surveying sample examination. Original edms were individual units used only for distance measurements. This sample exam closely mirrors the complete exam experience by covering the 5 primary. Total station and its applications in surveying gis resources.

Surveying was essential at the dawn of history, and some of the most significant scientific discoveries could never have been implemented were it not for the contribution of surveying. These corrections are documented in the user manuals of. Trilateration, method of surveying in which the lengths of the sides of a triangle are measured, usually by electronic means, and, from this information, angles are computed. A total station ts or total station theodolite tst is an electronicoptical instrument used for surveying and building construction. For in depth discussions of edm principles, you should read publications, such as surveying theory and practice, by davis, foote, anderson, and mikhail. Microwave edm in either case the measurement is the total distance from the instrument to the reflector and back to the instrument. It based on the principles of planks law in which electromagnetic. Material is removed from the work piece by a series of rapidly recurring current discharges between two electrodes, separated by a dielectric liquid and subject to. Aug 29, 2015 the general principles of surveying are. Chapter 12 electronic surveying equipment chapter 12 of the ea3 traman introduced you to electronic surveying equipment, specifically electronic distancemeasuring equipment. These points are usually on the surface of the earth, and they are often used to establish maps and boundaries for ownership, locations, such as.

Although taping and theodolites are used regularly on site total stations are also used extensively in surveying, civil engineering and construction because they can measure both distances and angles a typical total station is shown in the figure below. However, chain surveying is not recommended in the areas that are overcrowded with many details or the area is very large with too many undulations. Difference between one way slab and two way slab what is slab. Here the distance is measured with the help of electromagnetic waves such as micro wave, infra red wave and other similar waves. Prismsprisms are surveying tools used with edm and total stations toreflect the transmitted signals. Surveying, defined surveying can be defined as 1 the science and art of making all essential measurements in space. Prisms must be tribrachmounted if a higher level of accuracy is required control surveys. Fundamentals of surveying theory and samples exercises. Pdf engineering surveying 1 ce212 modern methods in. Uniti definitions, principle, various types of surveyingbased on methods and instruments, classifications, uses, necessity and use of various scales and verniers different types of ranging, tapes, chains, linear measurements, approximate, direct, optical and electronic methods, chain surveying, minor instruments for setting out right angle. As in the field of tacheometric surveying stadia method is the most widely used procedure so we will discuss the principle behind it.

A total station is an electronicoptical instrument used in modern surveying. Edm instruments use infrared light, laser light ormicrowaves. To simplify the procedures to obtain accuracy in surveying, the electronic distance measuring method was introduced. Electromagnetic edm instruments electromagnetic edms, first 1950s, use highfrequency radio developed in the waves. Such instruments were invented as early as 1950 in south africa by dr. Edm is commonly carried out with digital instruments called theodolites. Then the distance is measured with the help of time taken for the above process time taken by the wave for the emission and return. When systematic errors cannot be eliminated by procedural changes, corrections are applied to the measurements. Concept of surveying definition of surveying, classification, principle, accuracy 2. It is an electronic transit theodolite integrated with electronic distance measurement edm to measure both vertical and horizontal angles and the slope distance from the instrument to a particular point, and an onboard computer to collect data and perform. General principle of edm electromagnetic energy travels based on.

Direct reflex edm technology for the surveyor and civil engineer. The stadia method follows the principle that in similar isosceles triangles the ratio of the perpendicular to the base is constant. The spark generated by this process produces heat, which remove metal by erosion and evaporation. It is an electronic transit theodolite integrated with electronic distance measurement edm to measure both vertical and horizontal angles and the slope distance from the instrument to a particular point, and an onboard computer to collect data and perform triangulation calculations. Its principal modern uses are in the fields of transportation, building, apportionment of land, and communications. Electronic distance measurement instrument types, functions, uses. The total station is designed for measuring of slant distances, horizontal and vertical angles and elevations in topographic and geodetic works, tachometric surveys, as well as for solution of application geodetic tasks.

The principle of chain surveying is to provide a skeleton framework of straight lines, which can be plotted to scale if the lengths of these lines are predetermined either with a chain or a surveying tape. Designed to prepare you for the ncees ps exam, the principles and practice of surveying sample examination simulates the actual exam with realistic problems. Basic working principles of electronic distance meters springerlink. Mar 25, 2017 electrical discharge machining process works on the basic principle of spark generation and metal removed by spark erosion. Edm instruments are classified according to the type of carrier wave employed. According to the first principle, the whole area is first enclosed by main stations i.

Most common edm instruments used in surveying are based on this principle, regardless of whether they use. A practical project is used in an engineering surveying course to expose sophomore and junior civil engineering students to several important issues related to the use of basic principles of land. This is one the major difference between plane surveying and geodetic surveying. This surveying instrument is used in triangulation to measure the. Edm is electronic distance measurement survey it is basically measure the distance of two point. The calibrated distance, in this case, is the wavelength of the modulation on a carrier wave. Edm instruments are highly reliable and convenient pieces of surveying equipment and can be used to measure distances of up to 100 kilometers. Surveying or land surveying is the technique, profession, art and science of determining the terrestrial or threedimensional positions of points and the distances and angles between them. Chapter 8 electronic distance measurement edm advanced. Pdf introducing principles of land surveying by assigning a. Aug 03, 2018 however, chain surveying is not recommended in the areas that are overcrowded with many details or the area is very large with too many undulations. It covers surveying subjects thoroughly and with great technical depth.

Linear measurement different methods of direct measurement instrument for. Total station, gis and remote sensing now with oreilly online learning. It is a fundamental rule to always work from the whole to the part. Land surveying is basically an art and science of mapping and measuring land. Chain surveying or linear surveying surveying and levelling. Electronic distance measurement instrument types, functions. This chapter deals with the principles and procedures of separate electronic distance measuring device edm instruments that are mountable. For example, edm is typically slower than other machining methods, but it also tends to be more predictable, accurate and repeatable. In geodetic surveying higher degree of accuracy in angular and plane surveying can be achieved by taking the surface of the earth as curvature. Edm spark erosion is same as electric spark which burn a small hole in a piece of metal through witch it contacts. Engineering surveying 1 ce212 modern methods in surveying lectures. Edm typically works with materials that are electrically conductive, although methods have also been proposed for using edm to machine insulating ceramics. The present edm instruments have the following features, absolute circle reading, laser plummet, endless drives.

Electronic distance measuring instrument is a surveying instrument for measuring. To locate a new station by at least two measurements linear or angular from fixed reference points. Types of land survey methods based on the nature of field survey 1. Followings are the principles of surveying which should be kept in mind while determining the relative positions of points on the surface of earth. Oct 04, 2015 edm measurements, phase shift, frequency modulation. A land surveying professional is called a land surveyor. Calibrating edms yearly at a baseline calibration site.

Instruments using light or ir waves are classified as electrooptical instruments. It taught me to calculate state plane coordinate conversions by hand so that i understand what happens in a computer. Tacheometric surveying methods, detail procedures civil. This chapter is intended to supplement what you learned in the ea3 traman discussion, and, in addition, introduces you to the basic principles and uses of other types of electronic surveying equipment. Total station and its applications in surveying gis. Edm measurements, phase shift, frequency modulation. Principles of chain surveying or linear surveying civil. They are small, reasonably light weight, highly accurate, but still expensive. Created using mysimpleshow sign up at and create your own simpleshow video for free. Notes on electronic distance measurement mygeodesy.

M edm instruments for surveying may be divided into two classes. This is the type of text that will elevate the pls profession. Methods of design difference between working stress method and limit state method. Such instruments are less expansive because one active instrument and a battery are only needed at one end and instrument at the other end is. To learn more about edm principles, read publications such as surveying theory and practice by davis, foote, anderson, and mikhail. To learn more about edm principles, read publications such as.