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Slide 1:

SHEAT COLLEGE OF ENGINEERING LANDMINE DETECTION USING GPR PRESENTED BY- Prof. Shashank Singh SUBMITTED TO- Santosh Kumar Singh Topic- Electronics & Communication B.Tech ,3rd year 6th Sem.,E.C . Roll No.: 0838431023

CONTENTS:

CONTENTS Introduction History Hardware Description Sensors Employed Overview of the System Deployment Platform Testing & Evaluation

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Advantages Conclusion

INTRODUCTION:

INTRODUCTION Landmines and unexploded ordnance (UXO) are a legacy of war, insurrection, and guerilla activity. Landmines kill and maim approximately 26,000 people annually. In Cambodia, whole areas of arable land cannot be farmed due to the threat of landmines. United Nations relief operations are made more difficult and dangerous due to the mining of roads. Current demining techniques are heavily reliant on metal detectors and prodders.

HISTORY:

HISTORY As early as 1886, Heinrich Hertz showed that radio waves could be reflected from solid objects. In 1895 Alexander Popov , a physics instructor at the Imperial Russian Navy school in Kronstadt , developed an apparatus using a coherer tube for detecting distant lightning strikes. The next year, he added a spark-gap transmitter. During 1897, while testing this in communicating between two ships in the Baltic Sea, he took note of an interference beat caused by the passage of a third vessel. In his report, Popov wrote that this phenomenon might be used for detecting objects The German Christian Hülsmeyer was the first to use radio waves to detect "the presence of distant metallic objects". In 1904 he demonstrated the feasibility of detecting a ship in dense fog, but not its distance. In 1922 A. Hoyt Taylor and Leo C. Young, researchers working with the U.S. Navy, discovered that when radio waves were broadcast at 60 MHz it was possible to determine the range and bearing of nearby ships in the Potomac River. The British were the first to fully exploit radar as defence against aircraft attack.

HARDWARE DESCRIPTION:

HARDWARE DESCRIPTION The impulse GPR system developed in the International Research Centre for Telecommunications-transmission and Radar (IRCTR). Impulse GPR system comprises a Impulse generator, Transmitter, Receiver, Pulse extender, A/D converter, Processor and Visual display.

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IMPULSE GENERATOR The pulse generator delivered by SATIS Co. produces 0.8 ns monocycle pulses. The unique feature of this generator is its small trailing oscillations, which are below 2.4% of maximum amplitude during the first 2 ns and below 0.5% afterwards. The advantage of a monocycle in comparison with a mono pulse is that the frequency spectrum of the first one decreases to zero at low frequencies, which cannot be efficiently transmitted via the antenna system, while the frequency spectrum of the second one has a global maximum there. As a result, the magnitude of the field radiated by an antenna system fed by a monocycle is considerably larger than the magnitude of the field radiated by the antenna system fed by a monopulse with the same magnitude.

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ANTENNA SYSTEM The antenna system is one of the most critical parts of GPR system, because its performance depends strongly on the antenna system. The antenna system should satisfy a number of demands. The antenna system contains transmitter and receiver. The transmit antenna should: Radiate short ultra-wide band (UWB) pulse with small ringing. Radiate electro magnetic energy within a narrow cone in order to filter out undesirable back scattering from surrounding objects. Produce an optimal footprint on the ground surface and below it. The waveform of the radiated field on the surface and in the ground should be the same. The waveform of the radiated field in the ground should not depend on type of the ground.

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The receiver antenna should: Allow time windowing to isolate the direct air wave from the ground reflection. Provide sufficient sensitivity in order to receive very weak fields. Receive the field in a local point; effective aperture should not be larger than 1cm2. Be elevated at least 10cm above the ground surface. Additionally a possibility to measure simultaneously backscattered field in two orthogonal polarizations is desirable.

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A/D CONVERTER The transmitter sends out a series of electromagnetic pulses then listens with the receiver connected to high speed sampler which in turn feeds A/D Converter. A dielectric anomaly in the soil may cause the signal to be reflected back to a separate receiver antenna. This information is converted from nanoseconds to milliseconds so that it may be digitized by a conventional A/D converter for processing and display. The center frequency and band width of the transmitted pulse can be varied by changing the antenna and are chosen with respect to the required depth of penetration, soil type and size of the object to be detected. In this experiment, we used antennas with a center frequency 1.4GHz and 80% band width.

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PROCESSOR A/D converter converts the signal into digital signal which passes to the processor. Processor filters the signal. This signal shows presence or absence of surrogate mine in the soil. Processor allows passing the presence of mine detecting signal. Processor selects the mine detecting signal and passes to the visual display. VISUAL DISPLAY Visual display helps to see the range of targets. It displays the exact position of landmine.

SENSORS EMPLOYED:

SENSORS EMPLOYED If all mines were cased or had substantial metallic content, all that would be required for detection are metal detectors. The widespread use of plastic landmines necessitates development and deployment of additional detection technologies. Because there is no such thing as a plastic detector, other sensors attempt to exploit ancillary disturbances in the background, such as thermal, chemical, or dielectric.

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GROUND PENETRATING RADAR Because of the difficulty detecting the tiny amounts of metal in a plastic landmine with a metal detector, technology development has been funded in other areas. Ground penetrating radar (GPR) has been used for nearly 70 years for a variety of geophysical subsurface imaging applications including utility mapping and hazardous waste container location and has been actively applied to the problem of landmine detection for nearly 20 years. When parameters such as frequency range, antenna size, antenna separation, and system timing are optimized for detection of mine-sized objects in the near subsurface, GPR is quite effective in detecting both metal and plastic landmines in a variety of soils.

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OVERVIEW OF THE SYSTEM A series of measurements has been taken using a set of targets buried in the various types of soil. An FR-127-MSCB impulse ground penetrating radar ( ImGPR ) system developed by the Commonwealth Scientific and Industrial Research Organization (CSIRO), Australia, has been used for these measurements. The system collects 127 returns, or surroundings, per second, each composed of 512 samples with 12 bit accuracy. The sounding range may vary from 4 ns to 32ns. The GPR system uses bistatic bow-tie antennas which transmit wideband, ultrashort duration pulses.

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A SCAN Impulse GPR produces measurements of electromagnetic field scattered from the subsurface. This is detecting the graph as shown in figure. A scan is a method for detecting the presence and absence of surrogate mine in clay soil. The electromagnetic field is scattered by the GPR. Scattering pulses are detecting by the graph. This graph is Amplitude Vs Time. This graph is helpful to find the landmine and is used for visual inspection. The normal pulses are showing the absence of mines. The amplitude of the pulses are large as compared to other area. This shows the presence of mine. So we can detect the presence of mine in that clay soil.

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B SCAN A scan shows the presence of mine but we cannot expect the exact target. This problem is solving in B scan. B scan or Radargram is used to visualize the target of surrogate mine. A sample radargram is shown in figure. This showing the targets at approximately 55 cm and 100 cm. B scan calculating the distance from the soil to the mine. In this sample radargram showing the exact position. A scan and B scan is used for laboratory analysis. A return at a certain position along the distance axis is called an A scan. B scan is a graph which is Time delay Vs Distance. So B scan helps to calculate the penetration length. This graph helps to calculate the distance from ground to the mine.

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DEPLOYMENT PLATFORM US army handheld standoff mine detection system that is a self propelled cart with GPR system. As technological development for land mine detection tends to be a vehicular based system. This vehicular based system is shown in figure.

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self propelled cart with GPR system This vehicle is self propelled so it can use in war places. This is a vehicular based system because vehicle can carry the weight and supply the power. This does not mean, though, that handheld systems are limited to metal detectors. There are platforms that are smaller than full vehicles but larger than man deployable devices. This vehicle comprises a pulse generator, transmitter, receiver, pulse extender, A / D converter, processor and a visual display. This vehicle is passing through the soil, the pulse generator produces pulses and the transmitter transmits this signal to the ground. The soil contain the land mine, the receiver receives the ground reflecting signal.

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TESTING AND EVALUATION The U.S Army performs objective blind and scored testing at their testing facilities, which include carefully constructed mine lines. In this testing and evaluation environment, land mines are live (filed with explosive) because certain detection technologies such as Quadrople Resonance rely on detection of the actual explosive charge. However, on this test lines, the mines are unfused and thus do not detonate if they are run over by detection system.

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ADVANTAGES GPR has accurate measurements. GPR locates even small targets. It has been well founded by the defense. GPR operates by detecting the dielectric soils which allows it to locate even no metallic mines. Biological sensors can only operate for limited periods, but in GPR has no such limits. GPR has been tested in different environmental conditions.

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CONCLUSION Impulse GPR system is using for detecting anti-tank and anti-personal mines. Anti-tank mines are using for destroying the vehicles and anti-personal mines, which are designed to kill and maim people. Currently, very little technology is used in real-world demining activities. Active programs by the U.S Army in both land mine detection sensor development and systems integration are evaluating new technologies, incrementally improving existing technologies, increasing the probability of detection, reducing the false alarm rate, and planning out useable deployment scenarios. Through iterative design, build test cycles, and blind and scored testing at Army mine lanes, steady progress is being made.

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