Non-contact detection techniques and technologies for detection of objects in air, under-ground and under-water

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A compilation of various techniques, technologies and product types used for various applications for objects detection

A compilation of various techniques, technologies and product types used for various applications for objects detection

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  • 1. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. AttriWhite paperNon-contact detectiontechniques and technologiesfor detection of objects in air,under-ground and under-waterA compilation of various techniques, technologiesand product types used for various applicationsfor objects detectionRaman K. AttriGlobal Scientific and Technical Consultant(Scientific Instrumentation)rkattri@rediffmail.com
  • 2. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. AttriIn this white paper, we will present review and compilation of various object detection techniquescurrently available in different scenarios and situations. Automatic Object detection in the air, beneathother materials, under water and under the earth surface as well as over the surface is one of theadvanced sciences employing many principles of multiple engineering domains together. “See-through” methods – seeing beyond the visible objects, has been inherent desire of human being sincethe practice of science. Not only this, a craving to detect the objects without directly “seeing upon”them with naked eyes calls upon some automatic procedures and techniques[1].The object detection is done with the help of the device called object locators. Depending uponapplication these locators are named differently. Main purpose of a basic object locator is to detectthe presence of a particular object. Advanced object detectors would detect many other parametersfrom above list to give a comprehensive idea about the object being detected like its shape, size,orientation, motion, type etc[1]. When it comes to detection of object, the characteristics of interestcould simply be it presence or absence or it could be any one or combination of following parameters,• Presence of any object• Distance of the object• Shape of the object• Type & Material of the object• Speed (for moving objects)There are two popular methods of detecting the objects:- “See-upon” Method- “See-through” MethodThe automated “See-upon” method is used for confirming the presence of an object and “see-through” method is used for searching objects not visible directly. The “see-upon” method can beused for viewing and detecting objects beyond normal vision or enabling automated vision by adevice. The “see-through” method is to find the object beneath other object, which is not in directvision of the eye. Both are popular and its employment is purely dependent upon the applications.NON-CONTACT DETECTIONTECHNIQUES AND TECHNOLOGIESFOR DETECTION OF OBJECTS INAIR, UNDER-GROUND AND UNDER-WATER
  • 3. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. AttriTYPES OF OBJECT LOCATORSThe object locators (OL) are categorized based on objects being detected. Broadly, these areclassified as:1. Non-marked object locators2. Marked object locatorsA summary of various technologies & techniques used under various scenarios in both marked andnon-marked object detection is shown in the in Fig [1]. Both types of object locators, namely: non-marked and Marked shall be taken one by one.Fig [1]: Object Detection methods in various scenarios
  • 4. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. Attri1. NON-MARKED OBJECT LOCATORS (NMOL)In this technique the object which is being detected is not having particular identification mark or IDassociated with it. This technique employs the difference in properties of materials under detection,compares their relative response to a common trigger and based on that it discriminates betweenvarious objects. With discrimination, of course it can be tuned to detect only a particular object withcharacteristics of specific kind. One unique thing about Non-Marked Object locators is that they mostcommonly employ the reflection characteristics of the object. The object under question acts as amirror and hence will be a passive object.This technique can be used for detection of different types of objects in general like metal pipe,mines, waste, debris or cable depending upon the application. In this method generally a beam ofenergy is projected toward the object, this beam may be of ultrasonic, light, infrared, X-ray ormicrowave or RF energy. Different objects react differently to these energies and on the basis of theirreaction response, the desired object is identified. For example if a radio wave is projected towardsthe set of objects, various objects will reflect the energy back depending upon their location, size,direction and type of material etc. The reflected energy provides an equivalent of 3-D vision becauseenergy reflected from various points of the object will be different. So it gives a 3-D distribution of thereflected energy. Various materials will reflect the energy with varying intensity of reflection. Thisdemarcates the different materials of the objects under question. Different intensity level duringreflection would indicate presence of different objects. With extensive computation, desired object canbe detected. This computation can be done in CAD or other Computer imaging software &deciphered in form of physical attributes of the object. A general image is created and location of theobject of interest is pin pointed out of the total data about all the available objects detected. It uses alltraditional methods like RADAR, SONAR, LIDAR, GPR, GMD.
  • 5. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. AttriType of Non-Marked Object DetectorsDepending upon the application environment, where the object is being detected, we can have mainlyfollowing scenarios of Non-marked object detection:• In-the-Air or on the Surface (Non-Contact) object detection• Under-water (Non-contact) object detection• Objects detection beneath other materials (non-contact / non-destructive)• Under-ground (non-contact / non-destructive) object detectionVarious object location techniques and devices used in each of the scenario are being describedbelow.
  • 6. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. Attri1.1 IN-THE-AIR OBJECT DETECTIONThe object detection in air has been popular since the inception of air-war fare. The purpose isdetection of object in the air. The object usually used to be a moving aircraft. The same technique canbe employed for object detection in air, moving or stationary and object detection on the earthsurface. These days these object techniques have become very popular and are being widelyemployed in defense system, civic transportation, anti-burglar systems, and movement detection insecurity areas, unauthorized access control, traffic speed control and many more application ofsimilar kind. The object detection varies from small object detection to big object detection.Most popular techniques in this scenario are:i. SONAR (Sound Navigation and Ranging)ii. RADAR (Radio Detection and Ranging)iii. LIDAR (Light Detection and ranging)All of these three techniques basically work in similar manner, only difference being the kind ofenergy being employed by each of the method.
  • 7. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. Attri1.1.1 SONAR based In-the-air Object DetectionSONAR stands for Sound Navigation & Ranging (SONAR). This is very conventional and old system.It works on Echo (for distance) & Doppler Effect (for velocity). Echo is a process where the acousticwaves are sent towards the object in form of a burst and the reflected energy in response to this burstfrom the objects is received back[2]. This reflected energy is called echo. The time of transit betweentransmitted and received burst is calculated to find distance of the object from target using distance,time and speed relationship. If the object is stationary, the frequency of the incoming reflected energywould be same as transmitted one. For moving objects, the incoming wave will be reflected withdifferent frequency. This shift is proportional to the speed of the object and its sign is dependent onthe direction of the motion of the object being detected. This is called Doppler shift. And such adevice sometime is called Doppler radar. The change in frequency of the reflected wave gives thespeed of movement of the object. A typical shape of Doppler SONAR is is shown in Fig [2].The range is few 10s or 100s of meters and method is slow as the speed of sound is limited. Rangecan be increased by increasing acoustic power, but it will create sound noise. There is one solution toit. Ultrasonic frequencies are being used to avoid any audible noise. Lower the frequencies, larger isthe range of detection but accuracy will suffer. The ultrasonic based SONAR requires relativelysmaller setup consisting of small piezo-crystals as transmitters and receiversEarlier this technique was being used for determining presence and the velocity of the object only. Itdoes not give any idea about the size and shape of the object. But with the advent of computer signalprocessing techniques, it is possible to receive the signal reflected from multiple points of the object,process them simultaneously and generating 3-D profile of the object. This 3-D profile can beconverted into a 3-D object image visible on computer screen. This is called Imaging SONAR.Imaging SONAR is used for mapping of nearby objects.Fig [2]: SONAR Device for Transmission and Reception
  • 8. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. Attri1.1.2 RADAR based In-the-air Object DetectionRADAR stands for Radio Detection and Ranging. This works similar to SONAR, the difference beingthat in the RADAR, a high frequency RF wave is transmitted towards the object and the reflectedecho gives the distance and speed of the object. RADAR is generally used for detection as well asmapping through imaging of the moving objects in air like aircrafts etc[3]. The setup is usually very bigconsisting of a control system and dish antenna as shown in Fig [3]. It is worth mentioning here thataccuracy is inversely proportional to wavelength and hence directly proportional to frequency. Thus,the accuracy is very high due to high frequencies being used as compared to that of SONAR. Thistechnique is also used for fast moving objects. It measures distances and object detection in air up tofew 100s of meters or even few kilometers. Thus this is ideally suitable for defense applications.RADAR requires a bigger transmitting antenna, high powered transmitters and sophisticatedreceivers. So generally it is used for critical and strategic applications.1.1.3 LIDAR based In-the-air Object DetectionLIDAR stands for Light Detection and Ranging. Again this is similar to RADAR, only difference beingthat LIDAR sends a beam of light (coherent white light, LASER or IR) towards the object and thereflection is observed[4,5]. The time of transit gives the object distance. The way of finding the velocityof the object does not employs frequency shift (Doppler Effect) unlike SONAR or RADAR. It rathersends the multiple transmission bursts and hence receives the multiple reflections. It simply checksfor change in reflection time between multiple bursts and on the basis of shift in time, it finds thedirection and speed of movement of the object. LIDAR is extremely accurate due to smallerwavelengths and is used with distances in 1000s of kilometers in air (e.g satellites, missiles, meteorsand space applications)[4]. A typical LIDAR system is shown in Fig [4].Fig [3]: General RADAR setup consisting of Control Unit and AntennaFig [4]: LIDAR based transmitter-receiver systems (Courtesy StalkerRadar/Applied Concepts)
  • 9. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. Attri1.2 UNDER-WATER OBJECT DETECTIONThe under-water detection involves detecting objects like fishes, sub-marines, debris, ship wrecks,sea cables and under-water rocks. There are two popular techniques for detecting under-waterobjects:i. SONAR (using ultrasonic)ii. Imaging SONAR
  • 10. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. Attri1.2.1 Ultrasonic SONAR based under-water Object DetectionSONAR is preferable in water as sound waves travels best in water and can travel long distanceswithout much loss in energy. This ensures long range object detection. The device especially used forunder-water application is also called Echo Sounder[6]. Ultrasonic is preferred over audible sound ascreatures in sea are very sensitive to sound. The ultrasonic SONAR is generally used for detection ofpresence of objects and their respective distances. These objects are mainly submarine or creaturesnearby, ship wrecks, under-water cables, fishes. This device has defense, naval, as well ascommercial use[2]. These days most of the fishing vessels are fitted with Echo Sounder, which tellsthe presence of fish flocks in a particular area. The shape and size of under water ultrasonic SONARvaries depending upon the applications. The typical shapes of such SONAR is shown in Fig [5] andFig [6]. Generally they transmit the ultrasonic in form of a very narrow beam.Fig [5]: Various forms of Under-water SONARFig [6]: Typical Under-water SONAR
  • 11. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. Attri1.2.2 Imaging Ultrasonic SONAR based under-water Object DetectionThe Imaging Ultrasonic SONAR is same as one described for in-the-air object detection. For under-water applications the transmitter and receiver arrays normally have wider surface area like the oneshown in Fig [7]. The sonar receiver receives multiple reflections from various points of the object andcreates 3-D profile shape of the object to identify what it is. In addition to using for detection ofsubmarines, debris, slinked ships, underwater Gas pipelines, ocean fiber cables & underwatercreature detection, it can also be used for more strategic applications where the shape of object isvery important like generating warning signals on detecting whales etc. In a typical under-waterapplication, the Fig [8] shows a 3-D Ultrasonic Image of the slinked ship as detected by UltrasonicImaging SONAR[2,3].Fig [7]: Under-water Ultrasonic Imaging SONAR (Courtesy Imagenex,Inc)Fig [8]: Image of an under-water slinked ship taken by Imaging SONAR
  • 12. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. Attri1.3 UNDERNEATH HIDDEN OBJECTDETECTIONUnder-neath hidden object detection deals with locating objects beneath other objects or materials.For example airport baggage scanning for weapons etc, X-ray diagnostic scanning of human body forfractured bones, Ultrasound of human heart, ultrasound scanning of stones in the kidney etc. Thisdetection is based on reflection as well as transmission of the incident energy. There are two maintechniques in this category:i.Radiography (X-RAY)ii.Ultrasonic Imaging SONAR (Ultrasound)
  • 13. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. Attri1.3.1 Radiography (X-RAY) based hidden Object DetectionThe X-Ray radiography works on the basis of how much RF energy is passed across the interfacesand received at other side of the surface. The amount of received energy passed by various objectswill be characterized by the materials of the object. In this way its way of functioning is different fromRADAR, SONAR or LIDAR. A 2-D or a 3-D image of underneath objects with their shapes on thebasis of profile of RF energy passed is created. E.g. Bag checking at Airport, rods, pipes andelectrical wiring in the wall, fractured bones in medical diagnostic scan. Some of the application of X-ray for hidden object detection is shown in Fig [9] and [10].One important thing about radiography X-Ray is that it necessarily requires two surfaces to operateand setup is bigger. Further it requires lot of care and certification to operate such facility due tohazardous effects of X-ray due ot over exposure.X-RAY radiography mostly is a lab-based setup. These days the X-Ray radiography comes withcomputer based imaging as shown in Fig [11]. It can be a portable instrument or hand-heldequipment also as shown in Fig [12].Fig [9]: X-Ray radiography images used to detect the bonesFig [10]: Image of the Airport baggage taken by X-ray radiography
  • 14. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. AttriIt can be used for detection of any solid item made up of any material covered under other materials.In some cases also detection of pipes & bars etc in the wall or structures. In these applications, wallsare exposed to X-Rays from one side and a film is used to take image of the passed energy on theother side. The X-ray does not pass through metallic rods and bars and wires. Thus on the film anexact replica of the 1:1 2-D map of the solid items beneath the wall cements like pipes and cables etcwould be impressed. A very high energy X-Ray would be needed for such application and hence thearea need to be evacuated before applying X-Ray for object detection. For medical diagnosticapplication like fracture detection or other metallic objects like bullet detection inside the human bodymay require normal setup.Fig [11]: Computer based X-ray Imaging SetupFig [12]: hand-held X-Ray setup for object detection (Courtesy: SYder X-ray Imaging Systems)
  • 15. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. Attri1.3.2 Ultrasonic Imaging SONAR based hidden Object DetectionThis is same as used in in-the-air and under-water applications. Here range is not important. So arraysize could be very small and there can be trade-offs in the frequencies being used. Here again a 2-Dor 3-D image is created based on the amount of reflection from various materials. It requires only onesurface to operate. Transmitter itself acts as receiver. It can be used for underground applications likedetection of manhole, roads, pipes, dead bodies, cables etc under the soil or snow. One of theinteresting applications of such device is tracing the road after heavy snow fall and clearing the road.Computerized 3-D imaging coupled with sampling at regular intervals can be used to make a video ofmoving objects underneath (e.g. heart movement in medical applications)[7]. A 3-D Ultrasonic-imageby SONAR for locating a metal block underneath other material placed at any orientation is shown inFig [13].Fig [13]: UI SONAR Image taken of metal piece hidden inside othermaterial
  • 16. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. Attri1.4 UNDERGROUND OBJECT DETECTIONUnderground object detection poses the most challenging problem. The reason being the earthsurface consisting of varied kind of materials and all in almost solid form. The principle of objectdetection again remains mostly the reflection from various layers underneath the surface. However,underground object detection requires much higher energy to be transmitted towards earth surfacewhich should get penetrated well below the surface to a depth specified by the application involved.The most popular techniques are:i. Ultrasonic Imaging SONARii. Ground Penetrating RADAR (GPR)iii. Ground Metal Detectors (GMD)iv. Marker Locator (ML)The 4thtechnique namely Marker –locator is specifically discussed in next section: marked objectlocation.
  • 17. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. Attri1.4.1 Ultrasonic Imaging SONAR based Under-ground object DetectionThe principle of working is same as discussed previously. An ultrasonic beam with wide surface areais transmitted by relatively bigger transducer or array of transducers below the surface of the earth.Atypical shape of UI-SONAR for under-ground applications is shown in Fig [14].The energy of the transmitted wave has to be more than other applications. The frequency selectionis important in view of many layers of earth surface involved. It receives multiple reflections fromvarious layers in the earth and interfaces formed by buried objects underground and create a profileof various layers. The shape can be identified from this profile. Such device is generally used fordetection and locating underground pipelines, metal pieces, roads under snow cover, dead bodiesburied inside, cables etc. A 3-D profile image of under-ground metal piece buried inside earth surfaceas viewed by UI –SONAR is shown in Fig [15].Fig [14]: Typical Ultrasonic SONAR for under-ground objectdetection applications (Curtesy Imagenex Corp)Fig [15]: Underground metal numbers detection through ImagingSONAR
  • 18. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. Attri1.4.2 Ground Penetrating Radar (GPR) based Under-ground objectDetectionGPR is a nondestructive geophysical method that produces a continuous cross-sectional profile orrecord of subsurface features, without drilling, probing, or digging. GPR profiles are used forevaluating the location and depth of buried objects. It operates by transmitting pulses of ultra highfrequency radio waves (microwave electromagnetic energy) down into the ground through atransducer or antenna[8]. A typical setup of GPR is one shown in Fig [16] and Fig [17]. Thetransmitted energy is reflected from various buried objects or distinct contacts between different earthmaterials. The antenna then receives the reflected waves and stores them in the digital control unit. Inpractice, if UI SONAR is equivalent of SONAR then GPR is equivalent of RADAR[9].Fig [16}: Typical setup of GPR (Curtesy Geomodel, Inc)Fig [17]: GPR Transmitter & Antenna (Curtesy Geomedel,Inc)
  • 19. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. AttriWhen the transmitted signal enters the ground, it contacts objects or subsurface strata with differentelectrical conductivities and dielectric constants. Part of the ground penetrating radar waves reflect offof the object or interface; while the rest of the waves pass through to the next interface. The X and Ylocations are stored in the computer, which guarantees the accuracy of all measurements[9]. A profileof reflections from various layers and object as recorded by GPR looks like Fig [18].Ground penetrating radar waves can reach depths up to 100 feet (30 meters) in low conductivitymaterials such as dry sand or granite. GPR has the ability to scan hard to reach areas. Antennas withhigher frequencies of from 300 to 1,000 MHz obtain reflections from shallow depths (0 to about 30feet), and have high resolution. These high frequency antennas are used to investigate surface soilsand to locate small or large, shallow buried objects and rebar in concrete.There is no risk of radiation with GPRs, so there is no need to clear the area being scanned. In thisrespect, a GPR can suitably replace the X-Ray radiography previously described for detection ofunder the wall pipes, cables and bars etc[10]. The setup for such a scanning will be very small. Anysize area can be scanned without having to set up equipment again. As shown in fig [19], a GPR canbe used to locate the cables and metal rods in a wall also , very much like X-Ray but with a very smallsetup.Fig [18]: Underground layers and material detection profile givenby GPR (Courtesy Geomedel, Inc. and FutureGPR)Fig [19]: GPR being used for wall bars detection
  • 20. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. AttriThe image of wall rods can be very easily recoded by GPR for later processing on computer. To showeffective ness of the GPR, an image of rod mesh is shown in Fig [20] along with what it looks likeafter cementing the wall[11,12].The 3-D profile of data recorded by GPR as shown in Fig [18] can be viewed through processingsoftware in form of 3-D model of underground mesh of pipes with depth and orientation information[12,13,14]. This is shown in Fig [21].Fig [20]: Digital Image of GPR taken on a wall (CourtesyNGPRS, Inc)Fig [21]: 3-D mapping of underground pipe detection by GPR(Courtesy Geomodel, Inc. and GPRS, Inc.)
  • 21. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. Attri1.4.3 Metal Detectors based Under-ground object DetectionThe operation of metal detectors is based upon the principles of electromagnetic induction. Metaldetectors contain one or more inductor coils that are used to interact with metallic elements on theground. Pulsing current is applied to the coil, which then induces a magnetic field. When the magneticfield of the coil moves across underground buried metal, the field induces electric currents (callededdy currents) in the metal object. The eddy currents induce their own magnetic field back in the coil,which creates an opposite current in the coil, which induces a signal indicating the presence of metalobject[15]. GMD varies in shape depending upon application to application. It can be small portableunit like the one used by security personnel at airport entry to a sufficiently big sized commercial unitas shown in Fig [22].This method is used only for metal objects buried underground. But this method does not give anyidea about shape or depth. It only indicates its presence. Some underground metal detectors also useferromagnetic principle for detection. However GMD find wide application in commercial applicationsrequiring metal detection, strategic planet surface explorations for scientific studies etc.Fig [22]: Various shapes of commercial GMD (CurtesyGarrette Ace 150, www.garrette.com )Fig [23]: Ground Metal Detector in Use ( Courtesy CEIA,Italy)
  • 22. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. Attri2. MARKED OBJECT LOCATORS (MOL)This concept may be relatively new to some of the readers, so it will be highlighted in little moredetail. The marked object detection corresponds to detection of already pre-programmed objectshaving some unique identification are placed at specified locations with the purpose of tracing themanytime in future. These objects are called “markers”. The device used to locate such pre-programmed unique markers is called “marker locator”. The locator is mostly a hand-held unit asshown in Fig [24].Fig [24]: A typical hand-held Marker Locator(Manufacturer: 3M Worldwide)
  • 23. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. AttriThese markers usually communicate back with the locator in some specific manner, which pin pointthere presence in the area being scanned. The applications of markers are numerous. They aregenerally placed along with some network being laid underground. This network could be mesh ofgas pipes, water pipes, electrical cables, optical cables, telephone cables, sewerage pipes of anyother utilities. These utilities may be required to be traced any time in the future[16]. Markers-locatorcombination ensures its tracing without excessive digging. One simple example could be locating thesewerage man-hole lid, which gets buried inside the charcoal layers due to multiple carpeting of theroads over the years. In that case, utility company can not afford to dig the entire road; rather theyneed to exactly pin-point the location of the lid and dig it there only. In such cases, a pre-programmedmaker will be fitted with the lid, which will be detected later by the marker. The fig [25] shows how aMarker-locator is used.Fig [25]: Detection of maker with a locator (Curtesy 3Mworldwide, Inc.)
  • 24. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. AttriThe objective of locator is only to detect those specific markers only irrespective of any other object invicinity. The marker-locator interactions use some principle of physics like resonance, induction orRFID or combination of these.The marker generally is a plastic round ball (active or passive) which works on a particular principle ofthe physics and these are detected using complementary techniques. Mostly the markers are tunedcalls. These markers can have various shapes ranging from round ball, disk or cylinder shaped.Some of the typical shapes of the markers manufactured by various companies are shown in Fig [26].These shapes are used for various applications and depends upon where the marker will be fitted.For example in a narrow trench, a ball marker will be used, while with sewerage lids, a disk typemarker may be used.Markers and their detectors have to be compatible with each other and usually come in form of pairs.Marker of particular type may not be detectable by the detector of some other company unlessmarker is designed using industry standard specifications and principles. So each marker can be saidto be tunable to the detector.In marker-locator combination, major concern would be to detect two characteristics:• Location of marker• Depth of marker below surfaceUtility companies face increasing congestion underground and this can lead to problems when tryingto locate their own cables and pipes amidst the jungle of cables and pipes of other facility providers.ML helps to solve these problems.Fig [26]: Various shapes of underground utilitymarkers (Courtesy: 3M worldwide and TempoTextron Corporation)
  • 25. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. AttriPurpose of the ML is not to dig out the marker, but to find the map of the underground utility mesh.Marker Locator just do not points to the presence rather it also points the location, depth, type of themarker[17]. Some advanced markers scan the surface for all the different markers and providelocations of each of them. It can be tuned to work at specific frequency to detect the particular typesof markers only. It helps to locate and map the route, position & depth of the underground facility likepower, water, sanitary, telephone, gas, cable TV etc as shown in Fig [27].For each different kind of facility, a separate marker with unique color and frequency is used so thatselectively a particular facility characterized by that kind of markers may be located in future. Thisfrequency depends upon what kind of maker we are trying to locate[17].The colors and frequency ofresonance of each marker is specified by universal standards framed by AWPA as shown in Figure[28] and Table [1]. While the facility is being laid out, specific markers depending upon the utility arefixed up at particular points or bends on the pipes or cables or wires.Table [1]: AWPA color codes and Frequency standards for various utilities markersFig [27]: Installation arrangement of various markers withlocator (Courtesy: 3M worldwide)Fig [28]: Color Codes being used for Markers of various utilities(Courtesy: Tempo Textron Corp)
  • 26. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. AttriNow there are Marker-locator in the market which comes with advanced features. Some locators like3M comes with a feature, by which it can read, write and lock the information into programmable BallMarkers. Each ball marker thus gives out its ID as well and locator not only detects its position, depth,type but also ID numbers too. The information can be a pre-programmed unique identificationnumber, facility data, owner information, application type, placement date.Some Marker-locator also comes with a PC interface through a standard RS232 serial port forenhanced resource management. This interface enables programmed information from markers to beread, stored with date/time stamp and transmitted back to PC. Multiple markers located at closeproximity can be read individually with sophisticated marker locator like EML 100 using digital signalprocessing techniques.Fig [29a]: 3M ScotchMark Marker Locator (Manufacturedby 3M worldwide)Fig [29b]: Marker Mate EML100 Marker Locator(Manufactured by Tempo Corp)
  • 27. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. AttriEND NOTEDepending upon the application, the object detection techniques can be chosen. There areapplications where the traditional techniques like SONAR, RADAR, LIDAR, GMD, GPR, ML, UI-SONAR are being used innovatively. Such systems are being used for many applications such asGeo-technical applications, crack locations in dams, earth surface fault location, buried treasures,ancient burred civilizations, structural analysis (for example that fo pyramid), snow cover thickness forglacier avalanche forecasts, planetary exploration, utilities layouts, telecom & fiber cable layout, non-destructive testing, automated machine vision, country border security, intrusion detection, airportbaggage checking and many more applications[18]. These techniques have the potential ofapplications in many more areas which are still being evolved. There are some of the applicationswhich use these techniques in combination together to get into altogether new application area likecombining it with thermal photography & IR photography to scan the sub-surface, underground riverwater detection, mineral detection and other details of earth surface. Other than geo-technical anddefense applications, these techniques are equally useful in commercial and industrial environment.
  • 28. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. AttriDISCLAIMERAll images and trademarks cited or used in this paper belong to their respective manufacturers.For details, please visit the websites for respective manufacturers. Author has compiled theinformation from relevant manufacturers for use by wider users who need to select theappropriate product or technique for their applications.Any part of this white paper can be reproduced or used in publication work without seeking anypermission of the author. However, the reference must be made to this publication withappropriate credit to the author. For using images or text for relevant product, appropriatepermission should be taken from the relevant manufacturers or company.ACKNOWLEDGMENTS AND CREDITS1. National Ground Penetrating Radar Service, Minneapolis, USA: www.ngprs.com2. Geomodel, Inc USA: www.geomodel.com3. Ground Penetrating Radar Systems, Inc, Ohio, USA: www.gp-radar.com4. FutureGPR, USA: www.futuregpr.com5. Metal Detector.Com Online Store: www.metaldetector.com6. Garrette Metal Detectors, Texas, USA, www.garrette.com7. 3M Worldwide Corporation: www.3m.com8. Tempo Textron Research Corporation, Vista, USA: www.tempo.textron.com9. www.locatorequipment.com10. Imagenex Technology Corp, Canada, www.imagnex.com11. Seascape, Netherland, www.seascape.nl12. Stalker Radar/Applied Concept, Dallas, Texas, USA, www.stalkerradar.com13. Sonar Imagining, Inc, Houston, Texas, USA, www.sonarimaging.com14. CEIA, Arizzo, Italy, www.ceia.netREFERENCES1. A.E. Koksal, Using Multiresolution Range-Profiled Real Imagery in a Statistical Object RecognitionSystem, S.M. thesis, Department of Electrical Engineering and Computer Science, MIT, 1998;2. Bao Zhigang, NISHINO, Research on the object detection using ultrasonic sensor, System ControlGroup, http://www.robot.mach.mie-u.ac.jp/english/research/esonic/esonic.html3. S.M. Hannon and J.H. Shapiro, “Active-Passive Detection of Multipixel Targets, Proc. SPIE 1222: 2-23 (1990).4. A.E. Koksal, J.H. Shapiro, and W.M. Wells, III, “Model-Based Object Recognition Using Laser RadarRange Imagery,” SPIE Aero Sense 99, Orlando, Florida, April 5-9, 1999.5. J.K. Bounds, The Infrared Airborne Radar Sensor Suite, RLE TR-610 (Cambridge: MIT ResearchLaboratory of Electronics, 1996); IRAR data release,http://cis.jhu.edu/mit_cis/laserradar/IRAR/IRARmain.html6. Underwater Research Lab at Simon Fraser University, Sept. 8, 2001http://www.ensc.sfu.ca/research/url/sonar/SARAS.html7. Robert A. Kane, Intraoperative Ultrasonography: History, Current State of the Art, and FutureDirections, Journal of Ultrasound Medicine, Vol 23, pp1407-1420. 20048. How GPR Works, GeoRadar Inc., http://www.georadar.com/howitwrk.htm9. Lambert Dolphin, BRIEF BACKGROUND ON GROUND PENETRATING RADARS, SRI International,Menlo Park, California, http://www.ldolphin.org/GPRbkgnd.html, November 7, 199710. J. Aaltonen and J. Nissen, Geological mapping using GPR and differential GPS positioning - a casestudy, GPR 2002: 9th International Conference on Ground Penetrating Radar, Ohio USA, April-May200211. Egil S. Eide and Jens F. Hjelmstad, 3D utility mapping using electronically scanned antenna array,GPR 2002: 9th International Conference on Ground Penetrating Radar, Ohio USA, April-May 200212. A. Wallis, A. Langman, and M.R. Inggs, A dynamically configurable GPR data acquisition and displayapplication, GPR 2002: 9th International Conference on Ground Penetrating Radar, Ohio USA, April-May 200213. A.P. Annan, S.W. Cosway, and T. DeSouza, Application of GPR to map concrete to delineateembedded structural elements and defects, GPR 2002: 9th International Conference on GroundPenetrating Radar, Ohio USA, April-May 200214. Gader, P., Mystkowski, M., Zhao, Y.: “Landmine detection with GPR using Hidden Markov Models”,IEEE Transactions on Geosciences and Remote Sensing v. 39 No. 6, 2001.15. Das, Y., McFee, J., Toews J., Stuart G.: “Analysis of an Electromagnetic Induction Detector for Real-Time Location of Buried Objects”, IEEE Transactions on Geosciences and Remote Sensing v.28No.3, May 1990.16. Raymond L. Sterling, Section6: Trends for the Future Development of Utility Locating Systems, UtilityLocating Technologies:A Summary of Responses to a Statement of Need Distributed by the FederalLaboratory Consortium for Technology Transfer, Feb 2000,http://www.federallabs.org/utilities/Presentations/Utility_Locating_Technologies_Report.pdf17. Leonhard E. 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  • 29. R. Attri Instrumentation Design Series (Electronics), Paper No. 2, August 2005Copyrights © 2005 Raman K. AttriAbout the AuthorAuthor is Global Learning and Training Consultant specializing in the areaof performance technology. His research and technical experience spansover 16 years of project management, product development and scientificresearch at leading MNC corporations. He holds MBA in OperationsManagement, Executive MBA, Master degree in Technology and Bachelordegree in Technology with specialization in Electronics and CommunicationEngineering. He has earned numerous international certification awards -Certified Management Consultant (MSI USA/ MRA USA), Certified SixSigma Black Belt (ER USA), Certified Quality Director (ACI USA), CertifiedEngineering Manager (SME USA), Certified Project Director (IAPPM USA),to name a few. In addition to this, he has 60+ educational qualifications,credentials and certifications in his name. His interests are in scientificproduct development, technical training, and management consulting andperformance technology.E-mail: rkattri@rediffmail.comWebsite: http://sites.google.com/site/ramankumarattriLinkedIn: http://www.linkedin.com/in/rkattri/Copyright InformationWorking paper Copyrights © 2000 Raman K. Attri. Paper can be cited withappropriate references and credits to author. Copying and reproduction withoutpermission is not allowed.