Concealed Weapon and Contraband
Imaging and Detection System
Technical Seminar Report
submitted in partial fulfilment of the requirements
for the award of the degree of Bachelor of Engineering
inElectronics and Communication Engineering
Electronics and Communication Engineering
College of Science and Technology
Rinchending: Phuentsholing, BHUTAN
AcknowledgementI am thankful to my Seminar Guide Mrs. Jigme Zangpo for his valuable guidance, encouragement and co-operation during the course of this seminar writing. I am also thankful to seminar coordinator Dr. Kazuhiro Muramatsu and to all my friends who provide me every possible facility and support while preparing the seminar report. It was because of the persistent help and encouragement from my guide and friends that I was able to complete my seminar report on time. Their persistent help and encouragement was really a constant source of inspiration to me. So I sincerely thank all the individuals who have helped and assisted me in carrying and bringing out this seminar report.
AbstractAt present scenario, bombs blast are rampant all around the world. Usually bombs went off in buses or underground station, the core area like town or city, theatre and squad field. This left many people dead and injured severely. This happened because of people having a trend towards the prevention of carrying weapons by people in everyday life. At one hand this is due to the increase of violence in everyday life, on the other hand it is caused by the possibility of terrorist attacks. Therefore, the device called concealed weapon and contraband imaging and detection system (CWCIDS) plays significant role to find an items considered to be weapons or contraband. For this context, the technologies include X-ray Imager, Microwave Rader Imager, Acoustic-Based Hard Object Detector, Walk-Through Metal Object Detector and MRI Body Cavity Imager. Thus, it helps us provide essential application like Detection, Imaging, Locating, Monitoring and Surveillance and Tracking.
List of AbbreviationsAbbreviation Description Page
CD-ROM Compact Disc Read Only Memory 4
IEEE Institute of Electrical and Electronics Engineers 6
SI Le Système International d’Unités6
MKS Metre-Kilogramme-Second 6
CGS Centimetre–Gram–Second 6
WiMAXWorldwide Interoperability for Microwave Access 10
DOI Digital Object Identifier 10
URL Uniform Resource Locator 10
List of Figures TOC h z c “Figure” Figure 3.1 Image of an object that is in the detection space PAGEREF _Toc524777373 h 5Figure 3.2 Indication of the presence of an object that is in the detection space PAGEREF _Toc524777374 h 5Figure 3.3 Two different arrangements of coloured paper on a glass plate that give two different images but transmit the same amount of light energy PAGEREF _Toc524777375 h 6Figure 5.1 Black-body emittance curve for a body at 37 EC PAGEREF _Toc524777376 h 9Figure 5.2 Active imaging system and target PAGEREF _Toc524777377 h 9Figure 5.3 Electromagnetic spectrum PAGEREF _Toc524777378 h 10Figure 6.1 Diagram of an implementation of a CW-Doppler radar system PAGEREF _Toc524777379 h 12Figure 6.2 Diagram of a metal detector with an object inside the detection space PAGEREF _Toc524777380 h 13
TOC o “1-3” h z “Title,1,Reference,1,Contents,1” Acknowledgement PAGEREF _Toc524777400 h iAbstract PAGEREF _Toc524777401 h iiList of Abbreviations PAGEREF _Toc524777402 h iiiList of Figures PAGEREF _Toc524777403 h ivContents PAGEREF _Toc524777404 h v1Introduction PAGEREF _Toc524777405 h 12POSSIBLE APPLICATIONS PAGEREF _Toc524777406 h 22.1Detection PAGEREF _Toc524777407 h 22.1.1Imaging-Based Detection PAGEREF _Toc524777408 h 22.1.2Image Recognition Requirements PAGEREF _Toc524777409 h 22.2Imaging PAGEREF _Toc524777410 h 32.3Locating PAGEREF _Toc524777411 h 32.4Monitoring and Surveillance PAGEREF _Toc524777412 h 42.5Tracking PAGEREF _Toc524777413 h 43TYPE OF INFORMATION OBTAINED PAGEREF _Toc524777414 h 43.1Imagers and Indicators PAGEREF _Toc524777415 h 63.2Example of an Indication and an Image PAGEREF _Toc524777416 h 64FORM FACTORS PAGEREF _Toc524777417 h 74.1Proximity PAGEREF _Toc524777418 h 74.2Motion PAGEREF _Toc524777419 h 74.3Portability/Transportability PAGEREF _Toc524777420 h 75PARAMETERS AFFECTING DETECTION PAGEREF _Toc524777421 h 85.1Sources of the Detected Energy PAGEREF _Toc524777422 h 85.1.1Passive Illumination PAGEREF _Toc524777423 h 85.1.2Black-Body Radiation PAGEREF _Toc524777424 h 85.1.3Active Illumination PAGEREF _Toc524777425 h 95.2Forms of Detected Energy PAGEREF _Toc524777426 h 95.2.1Electromagnetic Energy PAGEREF _Toc524777427 h 105.3Magnetic Field Interactions PAGEREF _Toc524777428 h 106THE TECHNOLOGIES PAGEREF _Toc524777429 h 116.1X-ray Imager PAGEREF _Toc524777430 h 116.2Microwave Radar Image PAGEREF _Toc524777431 h 116.3Infrared Imager PAGEREF _Toc524777432 h 126.4Magnetic Imaging Portal PAGEREF _Toc524777433 h 126.5Walk-Through Metal Object Detector PAGEREF _Toc524777434 h 136.6MRI Body Cavity Imager PAGEREF _Toc524777435 h 146.7Pulse Radar/Swept Frequency Detector PAGEREF _Toc524777436 h 147Conclusion PAGEREF _Toc524777437 h 16References PAGEREF _Toc524777438 h 17
IntroductionA weapon is any object that can do harm to another individual or group of individualsCITATION DLM98 l 1033 (D.L McMakin, 1998). This definition not only includes objects typically thought of as weapons, such as knives and firearms, but also explosives, chemicals, etc. Contraband items include illegal drugs and any other item that is controlled or forbidden by a particular law enforcement or corrections agency. Consequently, contraband may include tobacco, any metallic object that can be used to defeat security constraints, drug paraphernalia, etc.
Therefore, at present scenario, bomb blasts are rampant all around the world. Bombs went off in buses and underground stations, killed many and left many injured. Bomb blasts cannot be predicted beforehand.
However, there are a variety of different technologies either being used or developed for CWCIDS applications, such as x-ray imaging, microwave holography, acoustic detection, etc. These CWCIDSs may be utilized in a variety of forms including the following: hand-held close-proximity scanning; stationary positioned, walk-by scanning; hand-held, stand-off scanning; etc. Which of the forms used is limited by the given CWCIDS technology. For example, present technology precludes x-ray imaging from being using in a hand-held stand-off scanning device.
POSSIBLE APPLICATIONSDetectionDetection of a concealed weapon is the most basic CWCIDS application. Detection gives the operator information on the presence of objects in the detection space. The detection space is define as the volume over which the CWCIDS operator is searching. The operator, however, does not know what type of object is detected when using a detection-only CWCIDS, only that something was detected. The detected object may not even be hidden. For example, conventional walk-through metal detectors will let the operator know that metal objects have passed through the portal, but the systems do not identify the location of the metal objects (although some walk-through systems provide zoned detection). And, unless the magnitude of the indication is dependent on the mass of the metal passing through the portal, the operator will not know the size of the object CITATION DSd98 l 1033 (D.S. deMoulpied, 1998). Because detection is the simplest type of CWCIDS application, a detection should be the least expensive and easiest to maintain of all types of CWCIDSs.
Imaging-Based DetectionIt is another type of detection. CWCIDS that acquires images of the detection space and then uses image recognition to convert the image into an indication (such as an audible or visual alarm). The imaging and image recognition capability make such a detection very complicated and much more expensive than a simple detection type system. Moreover, the image recognition function of this system require access to or have a large information (data) storage capability.
Also, image recognition usually requires large computing power and does not at present provide real-time detection capability. Therefore, based on present technology, this type of CWCIDS could not be used to find contraband hidden on individuals in a line of moving people unless sufficient computing power is available.
Image Recognition RequirementsFor the computer to recognize a specific weapon or threat item, the computer will have to compare the threat item with an electronic catalogue of images of uniquely-shaped threat items, and this includes images for all possible unique orientations for each unique threat item. Only catalogued images of uniquely-shaped threat items are required for comparison because no new information is obtained if a catalogued image is only a scaled replica of another catalogued image. Unique orientations, on the other hand, are important because a weapon may have a significantly different appearance if viewed from the sides, the top, etc. The apparent uniqueness of a threat item based on its orientation, however, will also depend on the image resolution of the CWCIDS: the less resolution in the image, the less likely the unique orientations will appear different.
ImagingAn imaging include a detector or detector array and/or a scanning system, image acquisition hardware and software, display hardware, etc. Imaging CWCIDSs are much more complicated than detection-only systems. However, the information provided can be much more useful than a detection-only CWCIDS CITATION HFH69 l 1033 (Henry, 1969). How useful the image information depend on the clarity of the image. A very good example of a concealed object imaging system that exhibits high image clarity is the cabinet x-ray system used at airports to screen carry-on luggage.
Based on present technology, imaging would be used where throughput is not an issue, such as secondary screening at security checkpoints. Furthermore, depending on the technology used to obtain an image, imaging may be further restricted because of privacy issues. For example, there exist some imaging-type CWCIDSs, such as some x-ray imaging systems, that provide detailed images of anatomical features.
LocatingA locating-type CWCIDS is used to show the operator where a contraband item is hidden within the detection space of the CWCIDS. Locating an object in the detection space facilitates examination of the person with the concealed object. Although locating the contraband item does not require an image, but it be used to locate objects in the detection space.
Drawback of locating for CWCID device:
Difficult to maintain
Monitoring and SurveillanceMonitoring and surveillance imply a “hands-off” operation where a remotely located operator is warned or presence of the contraband item in the area being controlled or monitoredCITATION Smi97 l 1033 (L.G. Roybal, 1996).
A surveillance or monitoring application may also be performed in an uncontrolled environment, where the detection space may not be constant, or where relocation of the CWCIDS is required. A monitoring-type CWCIDS, therefore, must accommodate variable temperatures, exposure to environmental extremes (rain, snow, blowing sand, etc.), frequent movement, and relocation. If monitoring is performed in controlled areas, such as in buildings or parking areas and, therefore, has a specific detection space to examine, the CWCIDS may be housed within a controlled-environment enclosure to enhance the effects of changing environmental conditions.
TrackingTracking is the process of following or retracing the movements of a targeted item (or items) over time. A tracking-type CWCIDS, therefore, will provide the operator with information on the whereabouts of a target item. The tracking-type CWCIDS uses either an imaging-type or detection-only CWCIDS for basic object identification; which basic CWCIDS is used will depend on the detail required to identify an object. In addition, the tracking-type CWCIDS will have the ability to map the movements of the identified object over time. Tracking can be performed automatically or by an operator. A tracking for this application may be used in a variety of environmental conditions and, so, should be tolerant to environmental extremes.
TYPE OF INFORMATION OBTAINEDThe type of information provided for this particular concealed weapon detection system can be classify based on the number of dimensions contained in the information. The information provided by the CWCIDS are:
In geometry, a point is a 0D object, a line is a 1D object, a plane (flat surface) is a 2D object, and a non-flat surface or a volume is a 3D object.
Examples of 0D information from a CWCIDS are the audible and visual alarms from hand-held metal weapon detectors. With 0D information, all you know is that an object exists at an unspecified location within the detection space of the CWCIDS; the operator does not know if the item is a contraband item. The operator may know the size of the object if the alarm is proportional to the mass of the object. Examples of 1D information from CWCIDS are the vertical light-emitting diode (LED) display of some zoned walk-through metal weapon detectors. Although the zones are relatively large, it does provide some coarse information on the vertical distribution of metal objects within the portal region of the walk-through metal detector. All pictures are 2D information. Similarly, the planar images (like a photograph) from thermal and millimeter-wave imaging systems are examples of 2D information.
In figure 1, the 2-D image of an object in the target space is depicted. The area between the dashed lines is the detection space. If an object falls partially outside of the detection space, then the image will be clipped. In figure 2, the same detection space is examined by a 0D-type CWCIDS and, as shown, provides only an indication of the presence of the object and not any information on the distribution of objects within its detection space.
Figure STYLEREF 1 s 3. SEQ Figure * ARABIC s 1 1 Image of an object that is in the detection space
Figure STYLEREF 1 s 3. SEQ Figure * ARABIC s 1 2 Indication of the presence of an object that is in the detection spaceImagers and IndicatorsBoth imagers and indicators contain one or more detectors. Typically, a system that provides an indication will contain only one detector whereas an imaging system may contain many detectors, which is called a detector array. A detector array may contain thousands of individual detectors, such as the detector arrays used in camcorders. An imager may also use only one detector. In the case where the imager uses only one detector, the image is formed by scanning the detection space of the detector over the detection space of the image. The scanning can be done mechanically or electronically depending on overall system cost, ruggedness, and other requirements.
Example of an Indication and an ImageConsider a glass wall with opaque pieces of paper stuck to it; the paper blocks half of the transmitted light and can be removed from or moved around on the glass wall (see fig. 3). In figure 3, a light is located behind the glass wall. If you were to take a picture of the wall, you would get a representation of the paper attached to the wall at the time the picture was taken: this is an image, or 2D information. A light meter, on the other hand, will give a reading of the amount of light passing through the wall; this is 0D information. With the indicator, you could tell how much of the wall is covered by the opaque paper from the magnitude of the indication. However, you would not know how the paper is arranged on the wall. Both walls in figure 3 will give the same indication because in both situations half of the wall is covered with paper, and half the light is blocked.
Figure STYLEREF 1 s 3. SEQ Figure * ARABIC s 1 3 Two different arrangements of coloured paper on a glass plate that give two different images but transmit the same amount of light energyFORM FACTORSForm factors are design variables that are related to how a human operator will use a CWCIDS. Form factors affect not only the design of a CWCIDS, but also the choice of which detection technology is used. There are three type of form factors which CWCIDS application take into account. They are:
ProximityCWCIDSs have two general categories:
Close proximity use
Examples of close-proximity devices are hand-held and walk-through metal detectors, x-ray systems, and magnetic resonance imaging (MRI) systems that are being developed to look into body cavities.
Some stand-off devices require a minimum distance between the operator and the target. Examples of stand-off devices are police radar guns, infrared imagers, and cameras.
MotionMobility describes the degree to which the CWCIDS moved during operation. A hand-held metal detector is requires so that it be moved during the search for concealed metal objects. On the other hand a walk-though metal detector will not operate properly if it is in motion. Most indicator-type hand-held CWCIDSs require movement for normal operation. Likewise, Imaging-type CWCIDSs does not perform well if they are under motion. However, if the motion is provided by a computer-controlled robotic mechanism, and software is available to adjust the image for movement by the robot, then the imaging-type CWCIDS will perform normally during motion.
Portability/TransportabilityPortability defines how easily a system can be picked up and moved. Some CWCIDSs are permanently installed at a location whereas others are handheld and can be moved anywhere. Portable devices usually operate on battery (dc) power whereas stationary devices typically require line (ac) power. Correspondingly, the cooling requirements of stationary systems may be more demanding than hand-held devices, such as requiring cooling fans or water.
Examples of hand-held portable systems are the hand-held metal detectors and police radar. On the other hand, Walkthrough metal detectors is an example of stationary-use transportable walk-through systems.
PARAMETERS AFFECTING DETECTIONA CWCIDS collects data or an information about the detection space and transmits it to the operator. The data is collected by sensors that are designed to capture some form of energy that usually contains information about objects in the detection space.
Sources of the Detected EnergyThe CWCIDS which detected energy is either emitted, transmitted, or reflected by objects in the detection space. The detection space must be illuminated if the CWCIDS uses either reflected or transmitted energy to provide information on the detection space. The incident energy is the energy that illuminates objects in the detection space. The CWCIDS detects only the part of incident energy that is reflected by or transmitted through objects within the detection space. It is the reflected or transmitted energy that carries information on the objects in the detection space and ultimately that can be used to form an image or provide an indication.
Passive IlluminationIn passive illumination, the CWCIDS uses naturally occurring radiation or anthropogenic sources of radiation to obtain information about objects in the detection space.
Black-Body RadiationThe passive CWCIDS also use the naturally occurring radiation emitted by a “hot” object in the detection space to obtain information about that hot object.
“Hot” is relative and, it means anything that does not have a temperature of absolute zero (-273 EC or, equivalently, -459 EF).
Figure STYLEREF 1 s 5. SEQ Figure * ARABIC s 1 1 Black-body emittance curve for a body at 37 ECActive IlluminationCWCIDS supplies the energy that is used to illuminate the detection space and, therefore, the active-illumination for CWCIDS must contain a subsystem in order to generate and emit energy.
Figure STYLEREF 1 s 5. SEQ Figure * ARABIC s 1 2 Active imaging system and targetForms of Detected EnergyThe CWCIDS requires source of energy, such as light, microwave, or acoustic energy, to provide an image or an indication. There are two types of energy that can be used by a CWCIDS to interrogate a detection space: acoustic and electromagnetic energy.
Electromagnetic EnergyElectromagnetic energy is the energy associated with electromagnetic waves, and electric and magnetic fields respectively. Sunlight, x-rays, infrared, microwaves, and radio waves are all electromagnetic waves but they all have different wavelength. The wavelength of an electromagnetic wave is related to its frequency of oscillation.
Figure STYLEREF 1 s 5. SEQ Figure * ARABIC s 1 3 Electromagnetic spectrumMagnetic Field InteractionsThe magnetic field produced by a source might interact with a nearby object. Whether an interaction occurs and the type and strength of this interaction depends upon the following factors.
Material type that the object is made of
Size and shape of the object
Orientation of the object in the magnetic field and
Speed of the object through the magnetic field.
For an object to interact with the magnetic field, the magnetic field must be either time-varying, for active magnetic-field-based CWCIDS, or the object has to be moving with respect to the stationary magnetic field, for passive magnetic-field-based CWCIDS.
THE TECHNOLOGIES X-ray ImagerThe x-ray imager is the same technology that used in medical x-ray imagers. The person being scanned stands near a panel while an x-ray source is scanned across the body. Separate scan is required to each surface of the body to be imaged.
Theory of Operation
X-rays means in the form of electromagnetic energy. The x-rays used in these CWCIDS are of low energy and penetrate a few millimeters into the body. Weapon detection x-ray imaging employ an interaction called Compton scattering or backscattering. In Compton scattering, the x-ray photon interacts with an electrons bound to an atom. For this interaction, the electron absorbs some of the incident x-ray energy and the absorbed energy is transferred to the kinetic energy of the electron. The energy of the x-ray photon that interacts with the electron is therefore reduced by the amount transferred to the kinetic energy of the electron. This reduced energy x-ray photon is the Compton scattered x-ray photon which is used for imaging or locating conceal weapon.
Microwave Radar ImageThe radar imager can be used to image concealed objects. The microwave radar imager is a small, light-weight device that can be deployed at any location and be operated remotely. The microwave radar imager uses electromagnetic radiation in the frequency of 20 GHz to 100 GHz range.
Theory of Operation
The image is formed from reflections of the microwave energy by objects within the target space of the imager. Radar (an acronym for radio detection and ranging) is used to determine the motion of the reflecting object by detecting the Doppler-frequency shift in the reflected signal. The shift is the consequence of the object moving away from or closer to the source of microwave energy. In case, if the object is moving away, the return signal has a longer wavelength (lower frequency) and vice versa for the object moving toward the source.
Figure STYLEREF 1 s 6. SEQ Figure * ARABIC s 1 1 Diagram of an implementation of a CW-Doppler radar systemInfrared ImagerInfrared imagers are commonly used for a variety of night-vision applications for seeing vehicles and people.
Theory of Operation
The body at temperatures above absolute zero will emit radiation and the wavelength of the radiation peak is dependent on the temperature of the body, and the total power emitted from the body is also dependent on the size and emissivity of the body. Most thermal imagers have been designed to have a peak sensitivity near the peak emission wavelength (around 10 µm) of humans. Also, these thermal imagers have better than 0.1 EC temperature sensitivity, which provides the images to display detailed features, such as the facial features of people.
Magnetic Imaging PortalThis system use a set of small-sized closely-spaced antennae located around the perimeter of a doorway or portal. An image of the objects within the portal will be obtained as the objects which move through the portal. Depending on speed, CWCIDS could be used as a primary security screening tool. The spatial resolution of this system is presently 5 cm. Consequently, the image of a handgun would not be precise but it would be visible. A video camera image is also overlayed on the magnetic image to assist the operator for locating the object on the person.
Theory of Operation
The time-varying magnetic field generated from each transmitter antenna interacts or communicate with objects within the detection space. The interaction is based on the magnetic permeability and electrical conductivity of the object. The interaction of the generated magnetic field is detected at each receiver antenna. The metal objects in the target space are imaged by acquiring the signals for every receiver antenna and for each transmitter antenna. On order to obtain the data, one transmitter is turned on so that each receiver acquires a signal. Then the next transmitter is turned on and each receiver acquires a new signal. The process continues until all transmitters along the periphery of the portal illuminate the detection space and each receiver has acquired a signal.
Walk-Through Metal Object DetectorThe walk-through metal detector (WTMD) is a commonly used device for detecting metal weapons and contraband items. These devices are usually transportable; they can be moved by two people to different locations. WTMDs are used in close-proximity situations. Since most weapons are or contain significant metal, WTMDs can be used as the primary security screening tool in most situations, Detector coil Source coil Object Source electronics Detector electronics Magnetic field emitted from object Magnetic field emitted. Diagram of a metal detector with an object inside the detection space such as courthouses, VIP security, school security, inmate visitation, etc CITATION Nic00 l 1033 (Nicholas G. Paulter, September 2000).
Figure STYLEREF 1 s 6. SEQ Figure * ARABIC s 1 2 Diagram of a metal detector with an object inside the detection spaceTheory of Operation
WTMDs are metal detectors that use interaction of the time-varying magnetic field they produce with nearby objects for finding metal objects. This interaction results in the generation of an electrical current in the object, and this process of current generation is how the WTMD detects a metal object. In fact, the WTMD can detect the presence of an object comprised of any electrically conductive material. However, in most cases, the detection signal is too small to detect if the object is not a metal. The human body is also conductive, although not as conductive as a metal; but because of its size, the detection signal from the human body may be larger than the detection signal from certain small metal objects.
MRI Body Cavity ImagerThe body cavity imager uses magnetic resonance imaging (MRI) techniques or, more accurately, nuclear magnetic resonance imaging techniques. This is the same technology used in medical MRI systems. MRI system can find concealed objects deep within the body and also it is used as at high-security correctional facilities as a tertiary screening tool CITATION WNi68 l 1033 (W.Niblack, 1968).
Theory of Operation
Usually MRI works by exposing the person to a large magnetic field pulse and using a pulse of high frequency microwave energy to analysis the interaction of the magnetic field with the body. Specially, the magnetic field pulse interacts with the nucleus of atoms and the microwave pulse is a probe that is used to examine interaction.
Pulse Radar/Swept Frequency DetectorThe system uses a pulse radar to determine the range to the object and then uses a swept frequency illumination of the object to obtain information on the object. This system does not provide an image but it gives an indication of whether or not a threat item is present in the target space. The ability to determine the existence of a threat item requires that the system store these signatures in a data base. As the threat items change, the data base must be updated to accommodate these new threats.
Theory of Operation
A pulse of microwave or radio-frequency energy is used to illuminate the target space and the reflected signal provides information on range. In case of pulse radar, acquiring range information is achieved by measuring the time interval between the emitted illumination pulse and the return pulse. After the object position and range have been determined with the pulse radar subsystem, the object is illuminated by a swept frequency source. The swept frequency return signal from the object is then analysed to determine if the reflecting object is a threat item. In particular, the resonance of the reflecting object is used to extract information about the object, therefore providing a signature for the object. The object’s electromagnetic signature is then compared to that of known handgun signatures, and an alarm is automatically activated if the signatures match.
ConclusionCWCIDS is the technology or instruments that designed to finds items considered to be weapon or contraband. The CWCIDSs utilized in a variety of forms including hand-held close-proximity scanning; stationary positioned, walk-by scanning; hand-held, stand-off scanning; etc.
The CWCIDSs also serve as the guidance or information that will help to the members of the law enforcement and correction community, who are present or potential users and operators of CWCIDSs, better understand the operation, limitations, and provide applicability of this technology tool to their specific application.
With the help of CWCIDS it provides possible applications that covers up detection, imaging, locating, monitoring and surveillance and tracking so that it prevent from suicide bomb and deadly explosion.
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