Frequency modulation is equipped in all EDM instruments. The site editor may also be contacted with questions or comments about this Open Educational Resource. Edm is a surveying instrument used to measure the distance electronically. c) 10 m b) Resolving amplitude All Rights Reserved. The Electrotape DM-20 is a transistorized microwave EDM. View Answer, 6. Sanfoundry Global Education & Learning Series â Surveying. Distance is measured as a function of the speed of light, an electromagnetic signal of stable frequency and elapsed time. Like its predecessors, this totally revised third edition is designed to make the subject matter more readily available to students proceeding to degrees in Survey ing and related fields. View Answer, 8. Measuring distances for a variety of survey purposes, such as the length of a baseline between two survey stations. a) Phase comparison a) Total wave Direct Reflex EDM Technology for the Surveyor and Civil Engineer R. Höglund & P. 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. View Answer. •The EDM is set up at one end of the distance to … View Answer, 7. From Price and Uren, 1989. a) Frequency, time period The calibrated distance, in this case, is the wavelength of the modulation on a carrier wave. The typical Total Station EDM can measure distances accurate to about 0.1 millimeter or 1/1000 foot, but most land surveying applications only take distance measurements to 1.0 mm or … In traverse a number of connected survey lines form a framework of survey. The content of this document is based on existing literature in the field, many years of practical experience of the authors in EDM calibration and on Explanation: In frequency modulation, the carrier wave has constant amplitude and frequency varies in proportion to the amplitude of the modulating wave. b) False Except where otherwise noted, content on this site is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. View Answer, 4. Modern EDM’s use the precision of a Quartz Crystal Oscillator and the measurement of phase-shift to determine the distance. The modulation pattern in the returning signal is read and interpreted by the onboard computer in the EDM. b) Measuring wave c) Amplitude, wavelength 5. Their range can be up to 30 km. Participate in the Sanfoundry Certification contest to get free Certificate of Merit. Phase Angles to Distance: Typically a modulated wave of length 20-m is generated by the EDM. a) 7*106 to 5*108 Hz View Answer, 9. 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. On the signal's return, the EDM can analyze it and determine the distance. If it measures a distance and obtains a double path length of 62.15 cycles, what is the length of the line measured? b) Super imposition of waves Used with survey and 3D point monitoring systems to measure changes in elevation and position of a point. All the codes mentioned come to a GPS receiver on a modulated carrier; therefore, it is important to understand how a modulated carrier is generated. View Answer. The calibrated distance, in this case, is the wavelength of the modulation on a carrier wave. d) Determination of frequency EDM (Tellurometer M/RA 1) Catalogue number: 1996.0200.01. This cyclic stressing can promote or inhibit fault slip, particularly at the deep roots of faults. View Answer, 2. The lowermost portion also isslustrates the ideal of modulation of the carrier wave by the measuring wave. This courseware module is part of Penn State's College of Earth and Mineral Sciences' OER Initiative. d) Time period Join our social networks below and stay updated with latest contests, videos, internships and jobs! It is a two-way system, but the EDM is both the transmitter and the receiver of the signal. Electronic Distance Measurement (EDM) is a fundamental feature of modern surveying Total Stations. Frequencies generated within an electronic distance measuring device (EDM) can be used to determine the elapsed travel time of its signal, because the signal bounces off a reflector (aka corner cube) and returns to where it started. © 2011-2021 Sanfoundry. d) 7.5*106 to 5*108 Hz 2217 Earth and Engineering Sciences Building, University Park, Pennsylvania 16802 The phase angle ( ) of the modulated wave can be detected by electronics in the EDM. Lower frequency is not suitable in_________ The first commercial unit, serial number 151, was unveiled in 1961. 1.8.5. The electronic distance measurement instrument (EDM) is a relatively new development in the field of surveying. Which of the following indicates the correct set of frequency employed in measuring process? d) Wavelength, frequency c) Distance measurement c) Wave length In EDM instruments these waves are generated, modulated and then propagated. • Measurement of distance is accomplished with a modulated microwave or infrared carrier signal, generated by a small solid-state emitter within the instrument's optical path, and bounced off of the object to be measured. View Answer, 3. The fundamental elements of the calculation of the distance measured by an EDM, ρ, are the time elapsed between transmission and reception of the signal, Δt, and the speed of light, c. Author and/or Instructor: Jan Van Sickle, Senior Lecturer, John A. Dutton e-Education Institute, College of Earth and Mineral Sciences, The Pennsylvania State University; V3 Consultants, Lakewood, CO. survey authorities who intend to or by law/regulations have to verify or calibrate their electro-optic distance meters (EDM) on a reference baseline. The sun and moon exert a gravitational tug on Earth that stretches and compresses crustal rocks. EDM is commonly carried out with digital instruments called theodolites. If 10mm is the accuracy considered, what will be the maximum value of λ for 1/1000 part? •Modern EDM’s use the precision of a Quartz Crystal Oscillator and the measurement of phase-shift to determine the distance. The first edition was published in 1978 by the School of Surveying, Universi ty of New South Wales, Sydney, Australia. b) Frequency In general terms, the instrument can take half the time elapsed between the moment of transmission and the moment of reception, multiply by the speed of light, and find the distance between itself and the retroprism (Distance = Elapsed Time x Rate). Here the distance is measured with the help of electro-magnetic waves such as micro wave, infra red wave and other similar waves. Frequencies generated within an electronic distance measuring device (EDM) can be used to determine the elapsed travel time of its signal, because the signal bounces off a reflector (aka corner cube) and … Classification of Traverse (Based on accuracy & Based on Instrument used ): a) True Distance measurement in modern surveying is done electronically. 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 … c) Resolving frequency d) Resolving wave length The Pennsylvania State University © 2020, GPS and GNSS for Geospatial Professionals. Surveying Equipment, Measurements and Errors 3.1 EQUIPMENT The procurement and maintenance of surveying equipment, tools and supplies are important parts of the Department’s survey effort. d) Frequency With Micro-Dist, however, the two units were interchangeable. In amplitude modulation, which among the following is constant? The principle of the measurement device in EDM, which is currently used in a total station and used along with electronic/optic theodolites, is that it calculates the distance by measuring the phase shift during the radiated electromagnetic wave (such as infrared light or laser light or microwave) from the EDM’s main unit, which returns by being reflected through the reflector, which is positioned at a measurement … They are reflected at the point up to which distance is to be measured from the instrument … Which of the following represents the correct set of modulation classification? Which canât be done in high frequency zones? For use, two units were needed, one to send the signal and the other to receive it. For example, if the EDM sends out a wavelength of 100 meters, then by looking at the fractional part of that 100-meter wavelength, it would be possible to determine the tens of meters in the distance. Frequencies generated within an electronic distance measuring device (EDM) can be used to determine the elapsed travel time of its signal, because the signal bounces off a reflector (aka corner cube) and returns to where it started. 1. c) 7.5*106 to 5.9*108 Hz b) 10 cm Answer: a. 6. b) Wavelength In 1957, the XIIth General Assembly of the International Scientific Radio Union recommended that the best available value for the velocity of electromagnetic waves in vacuum was : 299 792.5km/s ±0.4km/s. Here the electronic distance measuring equipment and a reflector are necessary to carry out the survey. Each piece of EDM equipment available at Engineer … In 1956 – Ordnance Survey – Geodimeter 4 - 299 792.4km/s ±0.5. An EDM only needs one oscillator at the point of origin, because its electromagnetic wave travels to a retroprism and is reflected back to its origination. On the signal's return, the EDM can analyze it and determine the distance. b) Distance calculation Araen S. Asanarimam Surveying Instrumentation Published 2018 Cover design & Printed in Nigeria by: Mbasule Digital Press, New Era Junction, Jalingo, Taraba State Surv. With an EDM, wavelengths of varying length can be sent out. Once the phase ( ) is determined it is a simple matter of converting phase to distance. c) Determination of wavelength d) 10000 cm Surveying Instrumentation Surv. The EDM is set up at one end of the distance to be measured and a reflector at the other end. (NSW Legislation, 2014a) and the Surveying and Spatial Information Regulation 2012 (NSW Legislation, 2014b). c) Amplitude Distance measurements can be made in two modes: with a reflector using an Infrared or visible laser electromagnetic wave and phase measurement or ‘reflectorless’ using a … In 1957 – Froome – Microwave interferometer – 299 792.5km/s ±0.10. Please send comments or suggestions on accessibility to the site editor. Contact Us, Privacy & Legal Statements | Copyright Information It yielded centimeter accuracy over distances from 100 meters to 40 kilometers, and in all weather conditions, day and night. The John A. Dutton e-Education Institute is the learning design unit of the College of Earth and Mineral Sciences at The Pennsylvania State University. Electronic distance measurement (EDM) is a method of determining the length between two points using electromagnetic waves. View Answer, 5. I, The Almanac, Time to First Fix and Satellite Health, Spread Spectrum and Code Modulation of L1 GPS Carrier, Imperfect Oscillators and Clock Corrections, Lesson 6: State Plane Coordinates and Heights, Lesson 7: Static Global Positioning System Surveying, Lesson 8: Real-Time Global Positioning System Surveying, Lesson 10: Global Navigation Satellite Systems and the Future, Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, Department of Energy and Mineral Engineering, Department of Materials Science and Engineering, Department of Meteorology and Atmospheric Science, Earth and Environmental Systems Institute, iMPS in Renewable Energy and Sustainability Policy Program Office, BA in Energy and Sustainability Policy Program Office, 2217 Earth and Engineering Sciences Building, University Park, Pennsylvania 16802. Distance is measured as a function of the speed of light, an electromagnetic signal of stable frequency and elapsed time. a) 10000 m During a survey, surveyors use various tools to do their job successfully and accurately, such as total stations, GPS receivers, prisms, 3D scanners, radio communicators, digital levels, dumpy level and surveying software etc. Unit length is equal to one half of the modulation wavelength of an EDM (Rϋeger, 1990). Distance measurement in modern surveying is done electronically. a) Modulation Modulating wave can also be known as ______ This set of Surveying Multiple Choice Questions & Answers (MCQs) focuses on “EDM – Modulation”. This Surveying Instrument is used in triangulation to measure the length of Base line because more accuracy is required to measure the length of base line. ELECTROMAGNETIC DISTANCE MEASUREMENT (EDM) Definition The electronic distance measurement instrument (EDM) is a relatively new development in the field of surveying. The direction and length of survey lines are measured with the help of an angular measuring device (Theodolite) and distance measuring device ( Tape, chain, EDM, GPS etc.). Figure 1: Traverse. A reflector or transmitter receiver at the far end reflects the light or a) Direct transmission View Answer, 10. The signal created by an electronic distance measuring (EDM) device in a total station is a good example of a modulated carrier. The amplitude of the solid Earth tide varies over a fortnightly (2-wk) cycle, as the sun and moon change their relative positions in the sky. Example: if =135o then this would represent EDM (Electrotape) Catalogue number: 1996.0195.01 ... Like the Tellurometer, Micro-Dist used data compression by means of modulation side-band folding. Area Computation & Tacheometric Surveying, Geographic Information System & Topographic Maps, here is complete set of 1000+ Multiple Choice Questions and Answers, Prev - Surveying Questions and Answers – EDM – Electromagnetic Waves, Next - Surveying Questions and Answers – Types of EDM Instruments, Surveying Questions and Answers – EDM – Electromagnetic Waves, Surveying Questions and Answers – Types of EDM Instruments, Analytical Instrumentation Questions and Answers, Electrical Measurements Questions and Answers, Digital Communication Questions and Answers, Linear Integrated Circuits Questions and Answers, Microwave Engineering Questions and Answers, Electromagnetic Theory Questions and Answers, Electronic Devices and Circuits Questions and Answers, Engineering Physics II Questions and Answers, Wireless & Mobile Communications Questions & Answers, Optical Communications Questions and Answers, Analog Communications Questions and Answers, Surveying Questions and Answers – Remote Sensing – Electromagnetic Energy, Wireless & Mobile Communications Questions & Answers – Linear Modulation Techniques. In Figure 6.14, if α is 2 0 30’ and the slope distance is 5,604.32 ft. what is the horizontal distance? a) Resolving modulation b) 7.5*106 to 4.5*108 Hz Most modulating EDM devices now use infrared or a visible laser (wavelength a few microns) as the carrier wave, modulated at around 1 GHz to give a modulation wavelength of about 30 cm. Distance measurement in modern surveying is done electronically. Distance is measured as a function of the speed of light, an electromagnetic signal of stable frequency and elapsed time. The College of Earth and Mineral Sciences is committed to making its websites accessible to all users, and welcomes comments or suggestions on access improvements. A total station ( TS) or total station theodolite ( TST) is an electronic/optical instrument used for surveying and building construction. Wave Modulation (3.8.3) 10 Methods of Measurement(3.8.4 to 3.8.7) 1-Time of Flight Measurement ... •In many EDM systems, the modulation frequency can be changed by small An EDM only needs one oscillator at the point of origin, because its electromagnetic wave travels to a retroprism and is reflected back to its origination. a) Amplitude Which of the following is constant in the case of frequency modulation? c) Super wave d) Wavelength measurement An EDM has a modulation frequency of 15 MHz that provides a wavelength of 65 ft. Proper care in the use, storage, transportation and adjustment of the equipment is a major factor in the successful completion of a survey. To practice all areas of Surveying, here is complete set of 1000+ Multiple Choice Questions and Answers. For many EDM instruments, an accuracy in measurement between 1 and 10 mm is specified at short ranges, and a phase resolution of 1 in 10,000 is normal. To understand the full scope of surveying, you … Cyclic error is usually sinusoidal in nature with a wavelength equal to the unit length of the EDM. It is a two-way system, but the EDM is both the transmitter and the receiver of the signal. To simplify the procedures to obtain accuracy in surveying, the electronic distance measuring method was introduced. Inscriptions: "TELLUROMETER" Discussion: The first successful microwave EDM was invented by Col. Harry A. Baumann of the South African Trigonometrical Survey, developed by Trevor Lloyd Wadley of the Telecommunications Research Laboratory of the South African Council for Scientific and Industrial Research (CSIR), and … as Amplitude Modulation (AM). d) Incubation wave EDM instruments are highly reliable and convenient pieces of surveying equipment and can be used to measure distances of up to 100 kilometers. Modern phase techniques are capable of __________ The latter states, among other things, that a surveyor must not use any ... unit length is equal to exactly one half of the EDM instrument’s modulation wavelength (Rüeger, 1996). b) Frequency, amplitude Each unit cost about $6,000 and weighed about 25 pounds. An EDM instrument can be tested and calibrated for all errors one at a time or . Frequency modulation is used in all EDM instruments, while amplitude modulation is done in … 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. The unit length is the scale on which the EDM measures the distance, and is derived from the fine measuring frequency. • Setting out a chain line as part of a chain and offset survey to carry out, for example, detail mapping. 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Edm ( Rϋeger, 1990 ) two survey stations as a function of the modulation wavelength of the EDM the... Following represents the correct set of 1000+ Multiple Choice Questions & Answers ( MCQs ) focuses on EDM... Be used to measure changes in elevation and position of a baseline between survey. Frequency varies in proportion to the amplitude of the EDM can analyze it determine..., 8 to distance: Typically a modulated wave of length 20-m is generated by onboard! Cyclic stressing can promote or inhibit fault slip, particularly at the Pennsylvania University., the two units were interchangeable to or by law/regulations have to verify or calibrate their electro-optic distance meters EDM... A distance and obtains a double path length of 62.15 cycles, what is the scale on which EDM... If =135o then this would represent with an EDM instrument can be detected by electronics the! Usually sinusoidal in nature with a wavelength equal to the unit length the! Is an electronic/optical instrument used for surveying and Spatial Information Regulation 2012 ( NSW Legislation, 2014a and... » for 1/1000 part, is the length of the following represents the correct of!