Patent Description:
Several attempts have been made to produce scanning systems that can detect certain materials (such as explosives or narcotics) in various items (such as luggage). However, these attempts have generally failed when attempting to scan items "in the open" without the use of radio frequency (RF) shielded containers. Instead, these attempts required that items be placed inside a shielded container. Moreover, the scan times used in these attempts have been quite long, often around one minute or longer. In addition, these attempts are often susceptible to and hindered by RF interference (RFI) in the ambient environment.

<CIT> relates to equipment for inspecting explosives and/or illicit drugs comprising a means for generating high-frequency pulses, an antenna coil which irradiates an object of inspection with the generated high-frequency pulses working as a radio wave and receives a nuclear quadrupole signal which is generated from the object of inspection when the object of inspection is excited by the radio wave, and a means for detecting explosives and/or illicit drugs in the object of inspection based on the nuclear quadrupole signal thus received, wherein the antenna coil is formed in the shape of a figure of "<NUM>" by using a high frequency coaxial cable so that two solenoid coil portions wound reversely to each other can be provided, and is used while facing the object of inspection.

<CIT> relates to the decoupling of an array of two or more closely spaced high temperature superconductor sensors in a nuclear quadrupole resonance detection system.

<CIT> relates to a method and apparatus for detecting quadrupole nuclei in motion relative to a search region, during the sensing operation, provides a system for decreasing the throughput time of quadrupole resonance (QR) detection systems.

Various preferred embodiments of the invention are found in the dependent claims.

In a first embodiment, a method includes transmitting first radio frequency (RF) signals towards an item through open space; receiving second RF signals from the item through open space, the second RF signals having one or more characteristics indicative of one or more materials within the item; and processing the second RF signals to identify the one or more materials within the item using nuclear quadrupole resonance 'NQR' spectrometry, wherein the first RF signals are transmitted towards the item using a first probe, wherein the second RF signals are received from the item using a second probe, and wherein the first and second probes are located in an upper portion of a table, the item positioned on the table.

In a second embodiment, a system comprising: a table; and a material detection system comprising: a transmit chain configured to transmit first radio frequency 'RF' signals towards an item through open space and comprising a first probe configured to transmit the first RF signals towards the item; a receive chain configured to receive second RF signals from the item through open space and comprising a second probe configured to receive the second RF signals from the item, the second RF signals having one or more characteristics indicative of one or more materials within the item; and at least one processing device configured to process the second RF signals to identify the one or more materials within the item using nuclear quadrupole resonance 'NQR' spectrometry, wherein the system is characterised in that the first and second probes are positioned in an upper portion of the table.

Other technical features may be readily apparent to one skilled in the art from the.

<FIG>, described below, and the various embodiments used to describe the principles of the present disclosure are by way of illustration only and should not be construed in any way to limit the scope of this disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any type of suitably arranged device or system.

As noted above, several attempts have been made to produce scanning systems that can detect certain materials (such as explosives or narcotics) in various items (such as luggage). However, these attempts have generally failed when attempting to scan items "in the open" without the use of radio frequency (RF) shielded containers. Instead, these attempts required that items be placed inside a shielded container. Moreover, the scan times used in these attempts have been quite long, often around one minute or longer. In addition, these attempts are often susceptible to and hindered by RF interference (RFI) in the ambient environment.

This disclosure is directed to various explosives, narcotics, or other material detection systems. Each material detection system is configured to rapidly scan items for explosives, narcotics, or other materials hidden or otherwise located within the items. The items that are scanned can vary widely based on the actual implementation of a specific material detection system. In some embodiments, for example, a material detection system can be implemented as a table scanner used in a travel security setting like an airport, in which case the material detection system may scan numerous items such as baggage, boxes, pelican cases, and backpacks (just to name a few). As a particular example, when implemented as a table scanner, the material detection system may be configured to rapidly scan numerous types of items placed on top of a table. Other types of material detection systems may also be implemented, such as material detection systems used to scan vehicles, cargo containers, or people. Each material detection system may be implemented at a fixed location, in a handheld or other portable device, on a vehicle, or in any other suitable manner.

Each material detection system uses a Nuclear Quadrupole Resonance (NQR) sensor probe, which may be placed under a tabletop or otherwise placed in the vicinity of items to be scanned. Because NQR uses lower-frequency RF signals, the tabletop or other housing structure is transparent to both "sense/exciting" signals that are transmitted from the sensor probe and response signals that are returned from target substances. Both types of signals also penetrate not only the tabletop or other housing structure but also most items being scanned. NQR is a proven technique where RF signals can be used to detect and uniquely identify materials such as many types of explosives and narcotics. Through the passive reduction or cancellation of RF interference, it is possible to build large sensors based on NQR. The passive RFI suppression in the material detection systems also enables large systems to operate without shielded containers. In some embodiments, the transmission of a sense/exciting signal towards an item is separated from the reception of a response signal from the item, helping to improve RF interference insensitivity. Among other things, the separation of the two functions facilitates the use of the transmit portion of the material detection system to enable additional RFI suppression processing. This also enables the use of the material detection system in an open environment without the use of a shielding enclosure, thereby making implementations such as tabletop systems and other "out in the open" implementations feasible.

In this way, scanning by each of the material detection systems is non-contact, rapid, and unambiguous when a target substance is detected. For example, a material detection system implemented as a table scanner in a travel security setting may scan each item in about one second, even in the presence of varying internal contents (such as clothing, electronics, toiletries, etc.). As another example, a material detection system may unambiguously identify various explosives like Composition-<NUM> (C4), pentaerythritol tetranitrate (PENT), trinitrotoluene (TNT), octogen (HMX), hexogen (RDX), and Semtex (a combination of PENT and RDX), as well as other chemicals or materials like potassium chlorate, ammonium nitrate, cocaine, and heroin. Also, the material detection systems can be safe for human scanning, have low false alarm rates, contain no moving parts, and/or be scalable in size to support multiple configurations (such as the ability to scan items of different sizes). Further, items can be scanned without needing to remove the contents of the items, which supports the scanning of items "in the open" without the use of RF shielded containers. This may be particularly useful when scanning items in airports, bus or boat terminals, cargo terminals, or other locations. In addition, RFI in the ambient environment can be suppressed or otherwise excluded, enabling use of the material detection systems in a large number of applications. Finally, since the material detection systems may require no RF shielding to achieve rapid detection of hidden explosives or other materials, the systems may operate in environments alongside other equipment like signal jammers.

This type of functionality may be used in various locations, such as civilian transportation centers (like airports and other travel terminals) or military base entry points. Among other things, the functionality may be used to help identify smuggling attempts, such as the transport of illicit materials across borders or through specific locations. The functionality may also be used to help identify explosives at checkpoints or other locations, where the explosives may be hidden under clothing, in bags/packages/vehicles, buried, or even located inside people. As can be seen here, the material detection systems are able to effectively detect one or more specified materials even in the presence of various types of barriers. While RF noise from a wide variety of sources (such as AM radio towers, jammers, and even lightning) have made previous NQR systems unsuitable for use in various scenarios, the disclosed material detection systems can operate indoors or outdoors with no additional shielding needed and can be used for rapid detection day or night.

<FIG> illustrates an example material detection system <NUM> according to this disclosure. As shown in <FIG>, the material detection system <NUM> includes a user workstation or other computing device <NUM>, a direct current (DC) power source or other power supply <NUM>, and a spectrometer <NUM>. The material detection system <NUM> also includes a transmit chain <NUM> having an amplifier <NUM> and a transmit tuner <NUM>, as well as a receive chain <NUM> having a receive tuner <NUM> and a low-noise amplifier <NUM>. The transmit tuner <NUM> is coupled to a transmit probe <NUM>, and the receive tuner <NUM> is coupled to a receive probe <NUM>.

The user workstation or other computing device <NUM> generally represents or supports a human-machine interface (HMI) that allows one or more users to interact with and control the material detection system <NUM>. For example, the device <NUM> may allow a user to initiate scanning of one or more items or configure the material detection system <NUM> to automatically perform continuous scanning of items. The device <NUM> may also present scanning results to the user, such as by indicating whether one or more explosives, narcotics, or other specified materials have been detected. The device <NUM> may further analyze data from the spectrometer <NUM> in order to determine whether one or more specified materials have been detected in one or more items being scanned (although the spectrometer <NUM> itself or another device may perform this function). The device <NUM> includes any suitable structure configured to interact with at least one user, such as a desktop computer, laptop computer, tablet computer, or specialized computing device.

The power supply <NUM> generally operates to provide operating power to at least some of the other components of the material detection system <NUM>. For example, the power supply <NUM> may provide operating power used to generate outgoing RF signals and process incoming RF signals. The power supply <NUM> includes any suitable source of electrical power, such as a DC power source or an alternating current-to-direct current (AC-DC) converter. The operating power provided by the power supply <NUM> may originate from any suitable source, such as an electrical grid or power generator.

The spectrometer <NUM> generally operates to analyze information related to wireless signals received by the material detection system <NUM> in order to separate and measure various spectral components. For example, the spectrometer <NUM> may be used to support NQR spectrometry in which RF pulses are transmitted and penetrate items being scanned (such as baggage, vehicles, cargo, or people) to excite chemicals within the items. This causes the chemicals to radiate unique RF "fingerprint" signals, where the fingerprint signals can be identified by the spectrometer <NUM>, the device <NUM>, or other device in order to determine whether specific chemicals are present in the items being scanned. The spectrometer <NUM> includes any suitable structure configured to separate and measure spectral components of signals. The spectrometer <NUM> may represent an "off the shelf" spectrometer or a customized spectrometer.

The transmit and receive chains <NUM> and <NUM> are respectively used to transmit and receive RF signals. For example, the transmit chain <NUM> may be used to generate RF signals (referred to as "sense/exciting" signals) that are transmitted through the transmit probe <NUM> into one or more items being scanned. The receive chain <NUM> may be used to receive and process RF signals (referred to as "response" signals) that are returned from the one or more items being scanned and that vary based on the chemicals or other substances in the one or more items being scanned. In this example, the amplifier <NUM> represents a high-power amplifier or other amplifier configured to amplify an input signal, which here is received from the spectrometer <NUM>. The amplified signal is provided to the transmit tuner <NUM>, which can tune to specific spectral components or different RF frequencies. Received response signals are provided to the receive tuner <NUM>, which can tune to specific spectral components or different RF frequencies. The specific spectral components or different RF frequencies contained in the response signals are provided to the low-noise amplifier <NUM>, which amplifies the received signals for processing by the spectrometer <NUM>.

The amplifier <NUM> represents any suitable structure configured to amplify outgoing signals for wireless transmission, and the low-noise amplifier <NUM> represents any suitable structure configured to amplify received incoming signals while imparting little or no noise into the amplified signals. The transmit tuner <NUM> and the receive tuner <NUM> each represents any suitable structure configured to tune to one or more specific spectral components or RF frequencies and to output tuned signals. In some embodiments, the transmit tuner <NUM> and the receive tuner <NUM> may each support auto-tuning, which enables the material detection system <NUM> to automatically tune to different RF frequencies and thereby scan/detect multiple threat substances. The scanning for multiple threat substances may occur sequentially or simultaneously depending on the implementation. Note, however, that the transmit chain <NUM> and the receive chain <NUM> may be implemented in any other suitable manner.

The transmit probe <NUM> is configured to transmit outgoing wireless RF signals based on input from the transmit tuner <NUM>, and the receive probe <NUM> is configured to provide incoming wireless RF signals to the receive tuner <NUM>. The transmit probe <NUM> includes any suitable structure configured to transmit wireless signals, and the receive probe <NUM> includes any suitable structure configured to receive wireless signals. In some embodiments, the probes <NUM> and <NUM> represent nested antennas, although separate antennas may also be used here.

In some embodiments, when at least one specified material is detected within an item during operation of the material detection system <NUM>, a display of the device <NUM> may provide a notification that turns from one color like green (meaning "clear" or "no specified materials detected") to another color like red (meaning "detection" or "at least one specified material detected"). The display may also identify the specified material or materials that have been detected (such as by displaying "RDX detected"), and optionally an audio alarm may be sounded. One or more additional alerts may also be distributed, such as to a Tactical Operations Center, Explosive Ordnance Disposal (EOD) or other response forces, or others. Also, in some cases, the presence of excessive metal content or other materials may block the sense/exciting signals and/or the response signals. In those instances, the device <NUM> (or another device) may be configured to generate an audible, visual, or other "shield alarm" (which may be similar to current X-ray/CT systems). The shield alarm can notify appropriate personnel of a potential problem with the scanning of a particular item or group of items.

Note that any other desired functionality may be implemented in the material detection system <NUM> as needed or desired using either the components shown in <FIG> or additional components. Examples of additional functions may include system health, monitoring, and built-in testing. Also, the material detection system <NUM> can be "ruggedized" for use in the field, meaning the material detection system <NUM> may be designed for use in various outdoor environments for prolonged periods of time. In addition, any testing can be expanded as needed or desired to improve system performance.

In some embodiments, the material detection system <NUM> overall may support the techniques disclosed in <CIT> , which describes how one or more materials can be detected using frequency-modulated NQR signals. In general, NQR is an approach in which excitation pulses in sense/exciting signals transmitted from the probe <NUM> are used to excite nuclei in one or more materials of interest (if present in an item being scanned) to an excited state. The energy of the excited state depends on a magnetic field in the item. The magnetic field in the item is modulated after the excitation pulses, and the nuclei in the material(s) of interest decay from the excited state so that they emit frequency-modulated radiation. This frequency-modulated radiation is received as the response signals by the probe <NUM>, so the response signals can be processed to determine if the one or more materials of interest are actually present in the item being scanned.

Moreover, in some embodiments, the transmit probe <NUM> and the receive probe <NUM> may be implemented as described in any of <CIT>; <CIT>; <CIT>; <CIT>; or <CIT>. Further, in some embodiments, the transmit tuner <NUM> and the receive tuner <NUM> may be implemented as described in <CIT>. In addition, in some embodiments, the transmit chain <NUM> and the receive chain <NUM> may use the techniques described in <CIT> to support the tunable transmission and reception of wireless signals.

Although <FIG> illustrates one example of a material detection system <NUM>, various changes may be made to <FIG>. For example, the actual implementation of the material detection system <NUM> can vary based on a number of factors, such as the material or materials to be detected, the type or types of items to be scanned, and whether the material detection system <NUM> is fixed, handheld, or movable. Many of these implementations may use at least some similar or identical components to support a common architecture, although this is not necessarily required.

<FIG> illustrates an example computing device or system <NUM> supporting material detection according to this disclosure. The device or system <NUM> may, for example, be used to implement one or more functions related to the user workstation or other computing device <NUM>, the spectrometer <NUM>, and/or other components of the material detection system <NUM>.

As shown in <FIG>, the computing device or system <NUM> may include at least one processing device <NUM>, at least one storage device <NUM>, at least one communications unit <NUM>, and at least one input/output (I/O) unit <NUM>. The processing device <NUM> may execute instructions that can be loaded into a memory <NUM>. The processing device <NUM> includes any suitable number(s) and type(s) of processors or other processing devices in any suitable arrangement. Example types of processing devices <NUM> include one or more microprocessors, microcontrollers, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or discrete circuitry.

The memory <NUM> and a persistent storage <NUM> are examples of storage devices <NUM>, which represent any structure(s) capable of storing and facilitating retrieval of information (such as data, program code, and/or other suitable information on a temporary or permanent basis). The memory <NUM> may represent a random access memory or any other suitable volatile or non-volatile storage device(s). The persistent storage <NUM> may contain one or more components or devices supporting longer-term storage of data, such as a read only memory, hard drive, Flash memory, or optical disc.

The communications unit <NUM> supports communications with other systems or devices. The communications unit <NUM> may support communications through any suitable physical or wireless communication link(s), such as a network or dedicated connection(s). As a particular example, the communications unit <NUM> may support communications with components used to transmit and receive RF signals (such as the transmit and receive chains <NUM> and <NUM>) and/or components used to analyze RF signals (such as the spectrometer <NUM>). The communications unit <NUM> includes any suitable structure configured to enable communications with one or more external components, such as a network interface card or a wireless transceiver.

The I/O unit <NUM> allows for input and output of data. For example, the I/O unit <NUM> may provide a connection for user input through a keyboard, mouse, keypad, touchscreen, or other suitable input device. The I/O unit <NUM> may also send output to a display or other suitable output device. Note, however, that the I/O unit <NUM> may be omitted if the device or system <NUM> does not require local I/O, such as when the device or system <NUM> represents a component that can be accessed remotely over a network.

Although <FIG> illustrates one example of a computing device or system <NUM> supporting material detection, various changes may be made to <FIG>. For example, in general, computing devices and systems come in a wide variety of configurations, and <FIG> does not limit this disclosure to any particular device or system. Also, various components in <FIG> may be combined, further subdivided, replicated, omitted, or rearranged and additional components may be added according to particular needs.

<FIG> illustrates an example user interface <NUM> of a material detection system <NUM> according to this disclosure. The user interface <NUM> may, for example, be presented on a display of the user workstation or other computing device <NUM>. However, the user workstation or other computing device <NUM> specifically or the material detection system <NUM> generally may have any other suitable user interface. Also, the user interface <NUM> may be used with any other suitable human-machine interface device.

As shown in <FIG>, the user interface <NUM> includes various buttons <NUM>, <NUM>, <NUM> that allow a user to control the overall operating mode of the material detection system <NUM>. In this example, the button <NUM> allows the user to initiate a scan of one or more items. This button <NUM> may be used, for example, when the material detection system <NUM> is not set for continuous scanning and the user waits for one or more items to be suitably positioned before initiating a scan. The button <NUM> allows the user to initiate a confirmation scan of one or more items. This button <NUM> may be used, for instance, if an initial scan of the one or more items was inconclusive or there is otherwise a desire to perform another scan of the one or more items. The confirmation scan may involve the use of more intense sense/exciting RF signals, the transmission of sense/exciting RF signals for a longer period of time, or a more detailed analysis of the return RF signals. The button <NUM> allows the user to toggle continuous scanning on and off, which means the user can control whether the material detection system <NUM> is set for continuous scanning of items.

A result indicator <NUM> provides a visual indication of the current scanning results. For example, the result indicator <NUM> may have a first color (such as green) and present first text (such as the word "clear") if no specified materials are detected in one or more items being scanned. The result indicator <NUM> may have a second color (such as red) and present second text (such as the word "detection") if at least one specified material has been detected in one or more items being scanned. The result indicator <NUM> may also provide other results, such as a "shield alarm" or other condition, and each condition may have its own unique color and text for the result indicator <NUM>. A textual description <NUM> may also be included in the user interface <NUM> in order to provide any other desired information to a user. For instance, the textual description <NUM> may identify the status of the material detection system <NUM> or identify the current detection results, such as by identifying one or more specified materials that have actually been detected by the material detection system <NUM>. A button <NUM> may be selected by the user to view a chart of information generated by the material detection system <NUM>, such as a chart containing the spectrographic characteristics of response signals as measured by the spectrometer <NUM>.

Although <FIG> illustrates one example of a user interface <NUM> of a material detection system <NUM>, various changes may be made to <FIG>. For example, the user interface <NUM> may present any other or additional information to a user and receive any other or additional information from the user as needed or desired. In general, user interfaces come in a wide variety of configurations, and <FIG> does not limit this disclosure to any particular user interface.

<FIG> and <FIG> illustrate an example travel security system <NUM> incorporating material detection capabilities according to this disclosure. The travel security system <NUM> here represents a modified version of the type of security system that is common in many airports and other travel terminals (at least in the United States). As shown in <FIG>, the travel security system <NUM> includes a waiting area <NUM>, where multiple travelers may queue or wait in line. Multiple podiums <NUM> are positioned where security personnel (such as Transportation Security Administration or "TSA" personnel in the United States) may inspect printed or electronic travel documents (such as boarding passes), personal identification documents (such as passports and drivers' licenses), and otherwise ensure that travelers are allowed to pass. The travelers may then allow their luggage to be inspected using X-ray machines <NUM> and recover their luggage at recovery locations <NUM> after the travelers themselves have passed through X-ray machines <NUM> or full-body scanners <NUM>. Inspection locations <NUM> may represent locations where physical samples of luggage can be captured and analyzed (such as by using swabs wiped over the luggage) or where other physical inspections or other inspections of travelers or luggage may occur. At least one specified location <NUM> may be provided in case travelers need to remove clothes as part of an inspection.

In this example, one or more scanning tables <NUM> may be provided at one or more locations in the travel security system <NUM>. Each scanning table <NUM> may include at least one instance of the material detection system <NUM>. In this example, the scanning tables <NUM> are provided before luggage is placed into the X-ray machines <NUM>. This may allow, for example, the scanning tables <NUM> to be used to scan luggage that is waiting to be passed through the X-ray machines <NUM>. Note, however, that the scanning tables <NUM> may be positioned at any other or additional locations in the travel security system <NUM>. Also note that in whatever position(s), user interfaces for the scanning tables <NUM> (such as user interfaces <NUM>) may be positioned where travelers can see the scanning results, or the user interfaces for the scanning tables <NUM> may be obscured from the travelers' view and viewed only by security personnel or other authorized personnel. At least one additional scanning table <NUM> may be located at a secondary inspection site <NUM>, which may represent an area where another NQR-based or other inspection may be performed. For instance, if a "shield alarm" or other alarm is issued for a particular item, the item may be inspected at the secondary inspection site <NUM> in a more detailed manner.

One specific example implementation of the scanning table <NUM> is shown in <FIG>, where upper and side surfaces of the scanning table <NUM> have been removed for illustration purposes. As can be seen in <FIG>, the scanning table <NUM> includes two instances of the material detection system <NUM>. One instance of the material detection system <NUM> includes a spectrometer <NUM>', an amplifier <NUM>', a transmit tuner <NUM>', a receive tuner <NUM>', and transmit and receive probes <NUM>'/<NUM>'. Another instance of the material detection system <NUM> includes a spectrometer <NUM>", an amplifier <NUM>", a transmit tuner <NUM>", a receive tuner <NUM>", and transmit and receive probes <NUM>"/<NUM>". Other components of each instance of the material detection system <NUM> (such as a power supply <NUM> and an amplifier <NUM>) may be positioned elsewhere in the scanning table <NUM> and are not visible in <FIG>.

In some embodiments, different instances of the material detection system <NUM> in the scanning table <NUM> may be used to scan for different types of materials. For example, one instance of the material detection system <NUM> may scan for one or more specific types of explosives or other materials, and another instance of the material detection system <NUM> may scan for one or more other specific types of explosives or other materials. In this case, a traveler may be instructed to pass his or her luggage or other items over both instances of the material detection system <NUM> in the scanning table <NUM>. In other embodiments, different instances of the material detection system <NUM> in the scanning table <NUM> may be used to scan for one or more common types of materials. For instance, each instance of the material detection system <NUM> may scan for the same type(s) of explosives or other material(s). In that case, a traveler may be instructed to place his or her luggage or other items over at least one instance of the material detection system <NUM> in the scanning table <NUM>.

The actual configuration of the table <NUM> can easily vary based on the intended material(s) to be detected and the arrangement of the security system <NUM>. Also, each instance of the material detection system <NUM> may have its own user workstation or other computing device <NUM>, or multiple instances of the material detection system <NUM> may be coupled to the same user workstation or other computing device <NUM> (in which case the device <NUM> may include a user interface that identifies which material detection system <NUM> detects one or more materials).

In particular embodiments, the scanning table <NUM> may have substantially the same size and dimensions as a standard or other "divest" table routinely used in airports and other travel settings. This may allow the scanning tables <NUM> to be easily retrofitted into existing installations where divest tables are already present. This can also help to avoid the need to rearrange other equipment in the security system <NUM> to accommodate the scanning tables <NUM>. However, this is not necessarily required, and each scanning table <NUM> may have any suitable size, shape, and dimensions (and different scanning tables <NUM> may have different sizes, shapes, and/or dimensions).

Note that, in this example, the scanning table <NUM> includes one or more sets of large probes <NUM>'-<NUM>", <NUM>'-<NUM>" located in the upper portion of the scanning table <NUM> and facing directly upwards into open air. Ordinarily, this arrangement of the probes <NUM>'-<NUM>", <NUM>'-<NUM>" would normally be associated with the worst case of RF interference. However, by using the approaches described in several of the patent documents incorporated by reference above (such as <CIT>; <CIT>; or <CIT>), it is possible to suppress the level of noise to enable the use of various NQR sensor probes, including large sensor probes facing open air.

<FIG> illustrates an example vehicle inspection system <NUM> incorporating material detection capabilities according to this disclosure, but which is outside the subject-matter of the claims. As shown in <FIG>, the vehicle inspection system <NUM> defines a space <NUM> positioned between two material inspection systems <NUM> and <NUM>. The space <NUM> in this example is sized and shaped to permit vehicles, such as cars, trucks, sport utility vehicles (SUVs), or tractor-trailers, to drive between the material inspection systems <NUM> and <NUM>. Each of the material inspection systems <NUM> and <NUM> may include one or more instances of the material detection system <NUM>, which are used to inspect the vehicles driving or otherwise positioned between the material inspection systems <NUM> and <NUM>.

<FIG> illustrates an example cargo inspection system <NUM> incorporating material detection capabilities according to this disclosure, but which is outside the subject-matter of the claims. As shown in <FIG>, the cargo inspection system <NUM> defines a space <NUM> positioned between two material inspection systems <NUM> and <NUM>. The space <NUM> in this example is sized and shaped to permit cargo <NUM>, such as pallets of items carried by a forklift <NUM>, to move between the material inspection systems <NUM> and <NUM>. Each of the material inspection systems <NUM> and <NUM> may include one or more instances of the material detection system <NUM>, which are used to inspect the cargo moving or otherwise positioned between the material inspection systems <NUM> and <NUM>.

<FIG> illustrates an example personal inspection system <NUM> incorporating material detection capabilities according to this disclosure, but which is outside the subject-matter of the claims. As shown in <FIG>, the personal inspection system <NUM> defines a space <NUM> positioned between two material inspection systems <NUM> and <NUM>. The space <NUM> in this example is sized and shaped to permit people to walk between the material inspection systems <NUM> and <NUM>. Each of the material inspection systems <NUM> and <NUM> may include one or more instances of the material detection system <NUM>, which are used to inspect the people walking or otherwise positioned between the material inspection systems <NUM> and <NUM>.

<FIG> illustrate example handheld inspection systems <NUM> and <NUM> incorporating material detection capabilities according to this disclosure, but which is outside the subject-matter of the claims. As shown in <FIG>, the handheld inspection system <NUM> is implemented in the form of a suitcase-type structure and incorporates one or more instances of the material detection system <NUM>. For example, the one or more instances of the material detection system <NUM> may be configured to transmit and receive RF signals through one or both of the larger sides of the suitcase-type structure. This form of the handheld inspection system <NUM> may (among other things) allow for easy transport of the material detection system(s) <NUM> and possibly inconspicuous use of the material detection system(s) <NUM>. As shown in <FIG>, the handheld inspection system <NUM> is implemented in the form of a metal detector-type structure and incorporates one or more instances of the material detection system <NUM>. For instance, the one or more instances of the material detection system <NUM> may be configured to transmit and receive RF signals through the bottom of the metal detector-type structure. This form of the handheld inspection system <NUM> may (among other things) allow for use of the material detection system(s) <NUM> in detecting certain items, such as buried mines or other explosives, under the ground.

<FIG> illustrate example vehicle-mounted inspection systems <NUM> and <NUM> incorporating material detection capabilities according to this disclosure, but which is outside the subject-matter of the claims. In <FIG>, the vehicle-mounted inspection system <NUM> is positioned on a retractable portion of a larger vehicle, where the retractable portion in this example is located in front of the vehicle. In <FIG>, the vehicle-mounted inspection system <NUM> is positioned at the end of a rotatable portion of a smaller vehicle. In both cases, each of the vehicle-mounted inspection systems <NUM> and <NUM> incorporates one or more instances of the material detection system <NUM>. This may allow, for example, the vehicles (or any other suitable moving platforms) to be used in various applications, such as the detection of buried mines, confirmation of targets detected by ground-penetrating radar, or detection of buried chemicals.

Although <FIG> illustrate various examples of inspection systems incorporating material detection capabilities, various changes may be made to <FIG>. For example, one or more instances of the material detection system <NUM> may be used in any other suitable manner. Also, luggage, vehicles, cargo, people, ground areas, or any other items may be inspected using one or more instances of the material detection system <NUM> in any other suitable manner. Thus, <FIG> do not limit the use of the material detection system <NUM> to the specific examples shown here. The material detection system <NUM> may be used in any other suitable manner, such as when implemented as a shoe or other footwear scanner, a postal or other package inspection scanner, or other inspection system, wherein each of these examples falls under the scope of the claims.

<FIG> illustrates an example method <NUM> for material detection according to this disclosure. For ease of explanation, the method <NUM> is described as involving the use of the material detection system <NUM> shown in <FIG>, which may include or be used in conjunction with the device or system <NUM> shown in <FIG>. However, the method <NUM> may involve the use of any other material detection system designed in accordance with this disclosure.

As shown in <FIG>, a signal to be transmitted wirelessly is generated and amplified at step <NUM>. This may include, for example, the spectrometer <NUM> or other source generating an RF signal containing desired pulses. This may also include the amplifier <NUM> amplifying the RF signal. The amplified signal is tuned to include desired spectral components or RF frequencies at step <NUM>. This may include, for example, the transmit tuner <NUM> tuning the amplified RF signal. First RF signals are transmitted towards one or more items being scanned through open space using a first probe at step <NUM>. This may include, for example, the transmit probe <NUM> radiating RF wireless signals as sense/exciting signals based on the output of the transmit tuner <NUM>.

Second RF signals are received from the one or more items being scanned through open space using a second probe at step <NUM>. This may include, for example, the receive probe <NUM> receiving response signals from the one or more items, where the response signals are based on the sense/exciting signals interacting with the one or more items. The received signals are tuned to include desired spectral components or RF frequencies at step <NUM>. This may include, for example, the receive tuner <NUM> tuning the received RF signals. The tuned portion of the received signals is amplified at step <NUM>. This may include, for example, the low-noise amplifier <NUM> amplifying the output of the receive tuner <NUM>.

The amplified and tuned portion of the received signals is processed to reduce RF noise or interference at step <NUM>. This may include, for example, the spectrometer <NUM> or other device performing any suitable noise or interference suppression technique. Note that some of the patent documents mentioned above describe techniques in which RFI or other RF noise can be suppressed, at least in part, using the design or operation of the probes <NUM> and <NUM>. In that case, there may be little or no need for further processing of the amplified and tuned portion of the received signals.

A determination is made whether one or more specified or target materials are identified in the one or more items being scanned at step <NUM>. This may include, for example, the spectrometer <NUM>, device <NUM>, or other device determining whether the spectral content of the received RF signals (as determined by the spectrometer <NUM>) indicates the presence of one or more explosives, narcotics, or other specified materials. The presence of one or more specified materials can be detected here using NQR performed by the material detection system <NUM>, which as noted above is unambiguous and has a low false alarm rate. If one or more specified or target materials are identified, an alert on a human-machine interface or other alert is triggered at step <NUM>. This may include, for example, causing the user interface <NUM> to alter the result indicator <NUM> to indicate that one or more target materials have been detected. This may also optionally include causing the user interface <NUM> to alter the result indicator <NUM> or the textual description <NUM> to identify the specific material(s) detected. This may further include transmitting an alert or other information to a Tactical Operations Center, response/EOD forces, or other destinations.

Although <FIG> illustrates one example of a method <NUM> for material detection, various changes may be made to <FIG>. For example, while shown as a series of steps, various steps in <FIG> may overlap, occur in parallel, occur in a different order, or occur any number of times. Also, various steps in <FIG> may be omitted or additional steps may be added as needed or desired.

In some embodiments, various functions described in this patent document are implemented or supported by a computer program that is formed from computer readable program code and that is embodied in a computer readable medium. The phrase "computer readable medium" includes any type of medium capable of being accessed by a computer, such as read only memory (ROM), random access memory (RAM), a hard disk drive (HDD), a compact disc (CD), a digital video disc (DVD), or any other type of memory. A non-transitory computer readable medium includes media where data can be permanently stored and media where data can be stored and later overwritten, such as a rewritable optical disc or an erasable storage device.

Claim 1:
A method (<NUM>) comprising:
transmitting first radio frequency 'RF' signals towards an item through open space;
receiving second RF signals from the item through open space, the second RF signals having one or more characteristics indicative of one or more materials within the item; and
processing the second RF signals to identify the one or more materials within the item using nuclear quadrupole resonance 'NQR' spectrometry,
wherein the first RF signals are transmitted towards the item using a first probe (<NUM>),
wherein the second RF signals are received from the item using a second probe (<NUM>), and
wherein the first and second probes (<NUM>, <NUM>) are located in an upper portion of a table (<NUM>), the item positioned on the table (<NUM>).