Electronic Distance Measurement (EDM) for Surveying

This presentation demonstrates Electronic Distance Measurement (EDM) devices for Surveying

1. Electronic Distance Measurement (EDM) Introduction to EDM : Definition and history Basic principles of operation Types of EDM Instruments : Total stations Theodolites with EDM capabilities Handheld laser distance meters Working Principles : Phase comparison method Time-of-flight method Frequency modulation method Applications of EDM : Surveying and mapping Construction and engineering Geographical Information Systems (GIS) Advantages of EDM : High accuracy and precision Efficiency and speed Long-range capabilities Reduced human error Limitations and Challenges : Environmental factors affecting measurements Calibration and maintenance of instruments Cost considerations Practical Demonstrations : Setting up and using EDM instruments Conducting field measurements Data recording and analysis

2. Methods for distance measurement Methods for distance measurement 1. DDM or Direct distance measurement - This is mainly done by chaining or taping. 2. ODM or Optical distance measurement - This measurement is conducted by tachometry, horizontal subtense method or telemetric method. These are carried out with the help of optical wedge attachments. 3. EDM or Electromagnetic distance measurement

3. Why EDM ? Traditional distance measurement techniques, such as using chains, tapes, or optical methods, have several issues that can be effectively addressed by Electronic Distance Measurement (EDM): Human Error : Manual methods are prone to human errors, such as incorrect reading or recording of measurements. EDM reduces these errors by automating the measurement process. Physical Obstacles : Chains and tapes require a clear line of sight and physical contact with the ground, which can be challenging in rough or obstructed terrains. EDM can measure distances without physical contact, making it suitable for difficult environments. Time-Consuming : Traditional methods are labor-intensive and time-consuming, especially over long distances. EDM significantly speeds up the process, allowing for quicker data collection. Accuracy : Chains and tapes can stretch or sag, leading to inaccurate measurements. EDM provides highly accurate measurements, often within millimeters, regardless of distance. Environmental Factors : Temperature, humidity, and wind can affect the accuracy of manual measurements. EDM instruments can compensate for these factors, ensuring consistent accuracy. Range Limitations : Traditional methods are limited in range and are not practical for very long distances. EDM can measure distances over several kilometers, making it ideal for large-scale projects. By addressing these issues, EDM enhances the efficiency, accuracy, and reliability of distance measurements in various fields such as surveying, construction, and engineering. Are you considering using EDM for a specific project or just exploring its benefits?

4. Why EDM ? Electronic Distance Measurement (EDM) is essential for several reasons: Accuracy : EDM provides highly accurate distance measurements, which are crucial for tasks like surveying, construction, and engineering. Efficiency : It significantly speeds up the measurement process compared to traditional methods like chains or tapes. Long Range : EDM can measure distances over long ranges, sometimes up to 100 kilometers, making it suitable for large-scale projects. Reduced Errors : The electronic nature of EDM reduces human errors that are common with manual measurement methods. Versatility : EDM instruments can measure both horizontal and vertical distances, and some advanced devices can also measure angles. These benefits make EDM a revolutionary technology in fields that require precise and efficient distance measurements .

5. Definition of EDM Electronic Distance Measurement (EDM) refers to the use of electronic devices to measure distances accurately and efficiently. These devices use electromagnetic waves, typically light or radio waves, to determine the distance between two points. The principle involves sending a signal from the instrument to a reflector and measuring the time it takes for the signal to return.

6. History of EDM Early Developments : The concept of using electromagnetic waves for distance measurement dates back to the early 20 th century . Initial experiments involved radio waves, but these were limited by their accuracy and range. Introduction of Light Waves : In the mid-20 th century , the use of light waves , particularly infrared and laser, revolutionized EDM. These waves provided higher accuracy and longer range compared to radio waves. First EDM Instruments : The first practical EDM instruments were developed in the 1950s and 1960s. These early devices were bulky and required significant power, but they laid the groundwork for modern EDM technology .

7. History of EDM Advancements in Technology : Over the decades, advancements in electronics, optics, and computing have significantly improved EDM instruments. Modern devices are more compact, accurate, and user-friendly. They often integrate with other surveying tools like total stations and GPS. Current State : Today, EDM is a standard tool in surveying, construction, and engineering. Instruments like total stations combine EDM with angle measurement, providing comprehensive data for various applications.

8. Key Milestones 1950s : Introduction of the first practical EDM instruments. 1960s-1970s : Development of more accurate and portable devices using light waves. 1980s-1990s : Integration of EDM with other surveying technologies, such as total stations. 2000s-Present : Continuous improvements in accuracy, range, and ease of use, along with integration with digital data collection and processing systems.

9. Practical Applications Surveying : Creating accurate maps and land surveys. Construction : Site layout, building measurements, and infrastructure projects. Engineering : Precise measurements for design and analysis .

10. Basic Principles of Operation of EDM Electronic Distance Measurement (EDM) operates on the principle of using electromagnetic waves to measure distances. Here are the key principles: Transmission and Reflection : An EDM instrument emits an electromagnetic wave, usually a laser or infrared light, towards a target. The wave travels to the target and is reflected back to the instrument. Time Measurement : The instrument measures the time it takes for the wave to travel to the target and back. This time is known as the “time of flight.” The distance is calculated based on the speed of the wave (which is the speed of light for laser-based EDM) and the measured time. Phase Comparison : Some EDM instruments use phase comparison methods. They compare the phase of the emitted wave with the phase of the reflected wave. The phase difference is proportional to the distance between the instrument and the target .

11. Basic Principles of Operation of EDM Frequency Modulation : In frequency modulation methods, the frequency of the emitted wave is varied. The instrument measures the frequency shift of the reflected wave to determine the distance. Compensation for Environmental Factors : EDM instruments often include sensors to measure temperature, pressure, and humidity. These environmental factors can affect the speed of the electromagnetic wave, so the instrument compensates for them to ensure accurate measurements.

12. Basic Principles of Operation of EDM

13. Basic Principles of Operation of EDM Principle of EDM Among these waves microwaves, infrared waves and visible light waves are useful for the distance measurement. It is essential to know the fundamental principle behind EDM to work with it. The electromagnetic waves propagate through the atmosphere based on the equation: v = f  = 1/T  f=1/T : (T-Time in seconds) Where v is the velocity of electromagnetic energy in meters per second (m/sec) f is the modulated frequency in hertz (Hz)

14. Steps in EDM Measurement Setup : The EDM instrument is set up at a known point. The target (reflector) is placed at the point to be measured. Measurement : The instrument emits the electromagnetic wave towards the target. The wave is reflected back to the instrument. Calculation : The instrument measures the time of flight or phase difference. It calculates the distance based on the measured time or phase difference and compensates for any environmental factors. Recording : The measured distance is recorded electronically, reducing the chance of human error.

15. Steps in EDM Measurement Ray AB is the survey line to me measured, having a length of D . The EDM equipment is placed at ends A and B. A transmitter is placed at A and a receiver is placed at B. The transmitter lets propagation of electromagnetic waves towards B. A timer is also placed. At the instant of transmission of wave from A the timer at 8 starts and stops at the instant of reception of incoming wave at B. This enable us to know the transit time for the wave from the point A to B. From the transit time and known velocity, the distance can be easily measured. Now to solve the problem arise due to difficulty in starting the timer at B, a reflector can be placed as shown below instead of a receiver at B.

16. Steps in EDM Measurement Measurement of distance with EDM and a Reflector As explained let the waves get transmitted from A and reflected from B. If the received signal is out of phase by a measure then equivalent distance is: d = Δ  (  / 360 ) Thus , the distance, D = ½ [n  + Δ  (  / 360 )] where n is the integral number of wavelength, in the double path

17. Practical Considerations Accuracy : EDM instruments can achieve millimeter-level accuracy. Range : Depending on the instrument, EDM can measure distances from a few meters to several kilometers. Speed : Measurements are quick, often taking just a few seconds. By understanding these principles, students can appreciate how EDM provides accurate and efficient distance measurements, making it a valuable tool in surveying, construction, and engineering .

18. Types of EDM Instruments: Microwave Instruments Infrared Wave Instruments Light Wave Instruments Laser Distance Meter Total Station Global Positioning System (GPS )

19. Microwave Instruments in EDM

20. Infrared Wave Instruments in EDM

21. Infrared Wave Instruments in EDM Infrared Wave Instruments are a type of Electronic Distance Measurement (EDM) device that use infrared wave to measure distances. Here are some key points about these instruments: Working Principle Amplitude Modulation : Infrared wave instruments typically use amplitude-modulated infrared light. The instrument emits an infrared beam towards a target, usually a prism reflector. Reflection and Return : The infrared beam is reflected back to the instrument by the prism. The instrument then measures the time it takes for the beam to travel to the target and back. Distance Calculation : The distance is calculated based on the speed of light and the measured time of flight. Some instruments may also use phase comparison methods to enhance accuracy 1 .

22. Infrared Wave Instruments in EDM Features Light and Economical : These instruments are generally lightweight and cost-effective, making them accessible for various applications. Mounting : They can be easily mounted on theodolites, which are instruments used for measuring horizontal and vertical angles. Accuracy : Infrared wave instruments can achieve an accuracy of approximately ±10 mm, which is suitable for many surveying and construction tasks. Range : The typical range of these instruments is up to 3 kilometers, making them useful for medium to long-distance measurements. Applications Surveying : Used for land surveying to measure distances between points accurately. Construction : Helps in site layout and ensuring precise measurements for building projects. Engineering : Used in various engineering applications where accurate distance measurements are crucial.

23. Infrared Wave Instruments in EDM Limitations Environmental Sensitivity : Infrared measurements can be affected by environmental factors such as fog, rain, and dust, which may scatter the infrared beam. Reflector Dependency : Requires a clear line of sight to the reflector, which can be a limitation in obstructed areas . EDM instruments that operate based on the principles of infrared waves: Leica DISTO Series Topcon GTS Series Trimble S Series Sokkia SET Series Nikon NPL Series

24. Light Wave Instruments in EDM

25. Light Wave Instruments in EDM Light Wave Instruments are a type of Electronic Distance Measurement (EDM) device that use visible or near-visible light waves to measure distances. Here are some key points about these instruments: Working Principle Modulated Light Waves : These instruments rely on the propagation of modulated light waves. The light waves are typically in the visible or near-visible spectrum. Transmission and Reflection : The instrument emits a modulated light wave towards a target, usually a prism reflector. The light wave is reflected back to the instrument. Phase Comparison : The instrument measures the phase difference between the emitted and reflected light waves. This phase difference is used to calculate the distance .

26. Light Wave Instruments in EDM Features Accuracy : Light wave instruments can achieve high accuracy, typically ranging from 0.5 mm to 5 mm per kilometer of distance 1 . Range : These instruments can measure distances up to 3 kilometers during the day and up to 2.5 kilometers at night 1 . Geodimeter : One of the first light wave instruments, known as the Geodimeter , was developed in Sweden. It set the standard for modern light wave EDM instruments 1 . Applications Surveying : Used extensively in land surveying to measure distances between points with high precision. Construction : Helps in site layout and ensuring accurate measurements for building projects. Engineering : Used in various engineering applications where precise distance measurements are crucial .

27. Light Wave Instruments in EDM Advantages High Precision : Light wave instruments provide very precise measurements, making them suitable for detailed surveying and engineering tasks. Non-Contact Measurement : These instruments do not require physical contact with the target, which is beneficial in rough or inaccessible terrains. Speed and Efficiency : They offer quick measurements, saving time compared to traditional methods. Limitations Environmental Sensitivity : Measurements can be affected by environmental factors such as fog, rain, and dust, which may scatter the light waves. Line of Sight : Requires a clear line of sight to the reflector, which can be a limitation in obstructed areas .

28. Light Wave Instruments in EDM EDM instruments that operate based on the principles of light waves: Leica Geosystems Geodimeter Trimble S Series Total Stations Topcon GPT Series Sokkia SET Series Nikon Nivo Series

29. Laser Distance Meter A Laser Distance Meter is a type of Electronic Distance Measurement (EDM) device that uses laser technology to measure distances accurately and efficiently. Here are the key aspects of Laser Distance Meters: Working Principle Laser Emission : The device emits a laser beam towards a target. The laser is typically in the visible or near-visible spectrum, often red or infrared. Time of Flight : The device measures the time it takes for the laser beam to travel to the target and reflect back to the instrument. This is known as the “time of flight” method. Distance Calculation : The distance is calculated based on the speed of light and the measured time of flight. Some devices may also use phase comparison methods to enhance accuracy.

30. Laser Distance Meter Features Portability : Laser Distance Meters are compact and portable, making them easy to carry and use in various environments. Accuracy : These devices can achieve high accuracy, often within millimeters, making them suitable for precise measurements. Range : Depending on the model, Laser Distance Meters can measure distances from a few centimeters to several hundred meters. Ease of Use : They are user-friendly, with simple point-and-click operation and digital displays for easy reading of measurements. Applications Construction : Used for site layout, measuring distances between points, and ensuring accurate measurements for building projects. Interior Design : Ideal for measuring room dimensions, furniture placement, and other interior design tasks. Surveying : Used in land surveying for quick and accurate distance measurements. DIY Projects : Popular among DIY enthusiasts for home improvement projects, such as measuring spaces for new furniture or renovations.

31. Laser Distance Meter Limitations Environmental Sensitivity : Measurements can be affected by environmental factors such as fog, rain, and dust, which may scatter the laser beam. Reflective Surfaces : The accuracy of measurements can be impacted by highly reflective or transparent surfaces. Range Limitations : While they are effective for short to medium distances, Laser Distance Meters may not be suitable for very long-range measurements compared to other EDM instruments.

32. Total Station A Total Station is a versatile and advanced type of Electronic Distance Measurement (EDM) instrument that combines several functionalities into one device. Here are the key aspects of Total Stations: Definition and Components Combination of Instruments : A Total Station integrates an electronic theodolite (for measuring angles), an EDM device (for measuring distances), and a computer or data collector for processing and storing data. Components : It typically includes a telescope, electronic distance meter, angle measurement system, and a microprocessor for data processing.

33. Total Station Working Principle Distance Measurement : The EDM unit in a Total Station uses laser or electromagnetic waves to measure the distance between the instrument and the target point. It emits a beam towards the target and measures the time it takes for the beam to return. Angle Measurement : The electronic theodolite measures both horizontal and vertical angles using electro-optical scanning of digital bar-codes etched on rotating glass cylinders or discs. Data Processing : The onboard computer processes the measured distances and angles to calculate precise coordinates of the target point. This data can be stored and transferred to other devices for further analysis.

34. Total Station Features High Accuracy : Total Stations provide highly accurate measurements, often within millimeters. Versatility : They can measure distances, angles, and elevations, making them suitable for a wide range of applications. Data Storage : The onboard computer allows for the storage and processing of large amounts of data, which can be easily transferred to other devices. Robotic Total Stations : Some advanced models are motorized and can be controlled remotely, reducing the need for an assistant. Applications Surveying : Widely used in land surveying for creating detailed maps and conducting topographic surveys. Construction : Essential for site layout, building measurements, and ensuring the accuracy of construction projects. Engineering : Used in various engineering applications, including infrastructure development and monitoring.

35. Total Station Advantages Efficiency : Combines multiple measurement functions into one device, saving time and effort. Precision : Provides highly accurate measurements, essential for detailed surveying and engineering tasks. Data Integration : Facilitates easy integration of measurement data with other software tools, such as CAD and GIS. Limitations Cost : High-end Total Stations can be expensive, which might be a consideration for some projects. Complexity : Requires training and expertise to operate effectively. Environmental Sensitivity : Measurements can be affected by environmental factors such as weather conditions and obstacles.

36. Global Positioning System (GPS) in EDM The Global Positioning System (GPS) is a satellite-based navigation system that provides location and time information anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites. While GPS is primarily known for navigation, it is also a powerful tool for Electronic Distance Measurement (EDM). Working Principle Satellite Signals : GPS works by receiving signals from a network of satellites orbiting the Earth. Each satellite transmits a signal that includes the satellite’s location and the exact time the signal was sent. Distance Calculation : The GPS receiver calculates the distance to each satellite based on the time it takes for the signal to travel from the satellite to the receiver. This is known as the “time of flight” method. Triangulation : By measuring the distance to at least four satellites, the GPS receiver can determine its exact position (latitude, longitude, and altitude) through a process called triangulation.

37. Global Positioning System (GPS) in EDM Features High Accuracy : Modern GPS systems can achieve accuracy within a few centimeters to a few meters, depending on the quality of the receiver and the correction methods used. Global Coverage : GPS provides global coverage, making it suitable for use anywhere in the world. Real-Time Data : GPS can provide real-time position and distance data, which is valuable for dynamic applications. Applications in EDM Surveying : GPS is widely used in land surveying to measure distances and determine precise locations. It is especially useful for large-scale surveys and in areas where traditional methods are impractical. Construction : In construction, GPS is used for site layout, machine control, and monitoring the progress of projects. Geodetic Measurements : GPS is used for geodetic measurements, which involve determining the precise shape and size of the Earth and the location of points on its surface.

38. Global Positioning System (GPS) in EDM Advantages Efficiency : GPS allows for quick and efficient data collection over large areas, reducing the time and labor required for traditional surveying methods. Versatility : It can be used in various environments, including urban, rural, and remote areas. Integration : GPS data can be easily integrated with other surveying and mapping tools, such as GIS and CAD software. Limitations Signal Obstruction : GPS signals can be obstructed by buildings, trees, and other obstacles, which can affect accuracy. Environmental Factors : Atmospheric conditions, such as ionospheric and tropospheric delays, can impact the accuracy of GPS measurements. Initial Cost : High-precision GPS equipment can be expensive, although the cost has been decreasing over time. Working Principles : Phase comparison method

39. Phase Comparison Method in EDM The Phase Comparison Method is a widely used technique in Electronic Distance Measurement (EDM) instruments. This method involves comparing the phase of the transmitted signal with the phase of the received signal to determine the distance. Here’s a detailed explanation of how it works: Basic Principle Modulated Signal : The EDM instrument emits a continuous wave signal that is modulated at a specific frequency. This signal travels to the target and is reflected back to the instrument. Phase Shift : As the signal travels to the target and back, it undergoes a phase shift. The phase shift is directly proportional to the distance traveled by the signal .

40. Phase Comparison Method in EDM Steps in Phase Comparison Method Transmission : The EDM instrument generates and transmits a modulated electromagnetic wave (usually light or infrared) towards the target. Reflection : The wave hits the target (often a prism reflector) and is reflected back to the instrument. Reception : The instrument receives the reflected wave and compares its phase with the phase of the transmitted wave. Phase Difference Measurement : The instrument measures the phase difference between the transmitted and received waves. This phase difference is used to calculate the distance. Mathematical Representation Phase Difference (  ) : The phase difference between the transmitted and received signals is given by: where (d) is the distance to the target and (  ) is the wavelength of the modulated signal. Distance Calculation : The distance (d) can be calculated as :

41. Phase Comparison Method in EDM Advantages High Accuracy : The phase comparison method provides high accuracy, often within millimeters, making it suitable for precise measurements. Efficiency : It allows for quick and efficient distance measurements, saving time compared to traditional methods. Long Range : This method can be used to measure long distances, depending on the power of the transmitted signal and the sensitivity of the receiver. Limitations Environmental Factors : The accuracy of phase comparison can be affected by environmental factors such as temperature, humidity, and atmospheric pressure. Complexity : The method requires precise instrumentation and calibration to ensure accurate measurements. Signal Interference : Interference from other signals or obstacles can affect the accuracy of the phase measurement .

42. Time-of-Flight Method in EDM The Time-of-Flight ( ToF ) Method is a fundamental technique used in Electronic Distance Measurement (EDM) instruments. This method involves measuring the time it takes for a light or radio wave to travel to a target and back to the instrument. Here’s a detailed explanation of how it works: Basic Principle Pulse Emission : The EDM instrument emits a short pulse of electromagnetic energy, typically a laser or infrared light. Travel to Target : The pulse travels to the target, which is usually a reflector or a specific point on the object being measured. Reflection and Return : The pulse is reflected back to the instrument from the target. Time Measurement : The instrument measures the time taken for the pulse to travel to the target and back. This is known as the “ time of flight .”

43. Time-of-Flight Method in EDM Steps in the Time-of-Flight Method Pulse Generation : The EDM instrument generates a short, intense pulse of light or radio wave. Transmission : The pulse is transmitted towards the target. Reflection : The pulse hits the target and is reflected back to the instrument. Reception : The instrument receives the reflected pulse. Time Measurement : The instrument measures the time interval ( t ) between the emission of the pulse and the reception of the reflected pulse. Distance Calculation : The distance ( d ) to the target is calculated using the formula: d= c ⋅Δt ​ / 2 where ( c ) is the speed of light (approximately ( 3 x 10 8 ) meters per second ).

44. Time-of-Flight Method in EDM Advantages Direct Measurement : The ToF method provides a direct measurement of distance, making it straightforward and easy to understand. High Speed : This method allows for rapid distance measurements, which is useful in dynamic environments. Versatility : It can be used for a wide range of distances, from very short to very long ranges. Limitations Accuracy : The accuracy of the ToF method can be affected by the resolution of the time measurement. High precision requires very accurate time measurement capabilities. Environmental Factors : Atmospheric conditions such as temperature, humidity, and pressure can affect the speed of light and, consequently, the accuracy of the distance measurement. Signal Interference : The presence of obstacles or other reflective surfaces can cause multiple reflections, leading to errors in the measurement. Applications Surveying : Used in land surveying to measure distances between points accurately. Construction : Helps in site layout and ensuring precise measurements for building projects. Industrial Automation : Used in various industrial applications for distance and position measurements. Consumer Electronics : Commonly found in devices like laser rangefinders and some advanced cameras for autofocus and depth sensing. Frequency modulation method

45. Frequency Modulation Method in EDM The Frequency Modulation (FM) Method is another technique used in Electronic Distance Measurement (EDM) instruments. This method involves modulating the frequency of the transmitted signal and measuring the frequency shift upon its return to determine the distance. Here’s a detailed explanation of how it works: Basic Principle Frequency Modulation : The EDM instrument emits a continuous wave signal whose frequency is modulated over time. This means the frequency of the signal changes in a known pattern. Transmission and Reflection : The modulated signal travels to the target and is reflected back to the instrument. Frequency Shift Measurement : The instrument measures the frequency shift (or difference) between the transmitted and received signals. This frequency shift is directly related to the distance traveled by the signal .

46. Frequency Modulation Method in EDM Steps in the Frequency Modulation Method Signal Generation : The EDM instrument generates a continuous wave signal with a frequency that varies in a known pattern (e.g., linearly increasing or decreasing). Transmission : The modulated signal is transmitted towards the target. Reflection : The signal hits the target and is reflected back to the instrument. Reception : The instrument receives the reflected signal. Frequency Shift Measurement : The instrument measures the frequency shift between the transmitted and received signals. This shift occurs because the signal travels a certain distance to the target and back. Distance Calculation : The distance ( d ) to the target is calculated using the formula: d = ( c ⋅Δf )/ (2 ⋅Δf m ) ​ where ( c ) is the speed of light, ( Δ f ) is the measured frequency shift, and ( Δ f m ) is the modulation frequency .

47. Frequency Modulation Method in EDM Advantages High Accuracy : The FM method provides high accuracy, often within millimeters, making it suitable for precise measurements. Long Range : This method can be used to measure long distances, depending on the power of the transmitted signal and the sensitivity of the receiver. Robustness : The FM method is less affected by environmental factors such as temperature and humidity compared to other methods. Limitations Complexity : The method requires precise instrumentation and calibration to ensure accurate measurements. Signal Interference : Interference from other signals or obstacles can affect the accuracy of the frequency measurement. Cost : Instruments using the FM method can be more expensive due to the complexity of the technology. Applications Surveying : Used in land surveying to measure distances between points accurately. Construction : Helps in site layout and ensuring precise measurements for building projects. Industrial Automation : Used in various industrial applications for distance and position measurements .