Abstract: A stepped-frequency radar signal is transmitted through a barrier. A transmitter of the stepped-frequency radar is on a first side of the barrier, a first object is on a second side of the barrier, and a second object that is distinct from the first object is on the second side of the barrier. A signal including a reflection of the transmitted signal from the first object and a reflection of the transmitted signal from the second object is sensed. The sensed signal is analyzed to determine that a first detection is associated with the first object and a second detection is associated with a second object.

Abstract: An apparatus includes an extendable wand, and a sensor head coupled to the wand. The sensor head includes a continuous wave metal detector (CWMD) and a radar. When the wand is collapsed, the wand and the sensor head collapse to fill a volume that is smaller than a volume filled by the sensor head and the wand when the wand is extended. Frequency-domain data from a sensor configured to sense a region is accessed, the frequency-domain data is transformed to generate a time-domain representation of the region, a first model is determined based on the accessed frequency-domain data, a second model is determined based on the generated time-domain representation, the second model being associated with a particular region within the sensed region, and a background model that represents a background of the region is determined based on the first model and the second model.

Abstract: A through-wall radar system includes a transceiver configured to receive and transmit multiple radar signals, each radar signal associated with a frequency that nominally passes through a barrier. The system includes a processor coupled to an electronic storage, the processor configured to sense a portion of a signal transmitted by the transceiver and analyze the sensed portion of the signal to determine a penetrability of a barrier. The system also includes an output configured to present a perceivable indicator related to the determined penetrability of the barrier.

Abstract: A stepped-frequency radar signal is transmitted through a barrier. A transmitter of the stepped-frequency radar is on a first side of the barrier, a first object is on a second side of the barrier, and a second object that is distinct from the first object is on the second side of the barrier. A signal including a reflection of the transmitted signal from the first object and a reflection of the transmitted signal from the second object is sensed. The sensed signal is analyzed to determine that a first detection is associated with the first object and a second detection is associated with a second object.

Abstract: Detection systems for scanning regions are disclosed. The detection systems may be used to detect various objects that are, for example, buried in the ground or obscured by being hidden on the body of a person. The detection systems include a sensor head having a continuous wave metal detector (CWMD) coil, radar antennas, and a transceiver electrically connected to a radar. The radar includes a transmit antenna configured to transmit electromagnetic radiation, and a receive antenna configured to sense electromagnetic radiation.

Abstract: An apparatus includes a sensor head including a continuous wave metal detector (CWMD), a radar, and a transceiver electrically connected to the radar. The radar includes a transmit antenna configured to transmit electromagnetic radiation, and a receive antenna configured to sense electromagnetic radiation. The transceiver is enclosed in a metal housing.

Abstract: A system and method for detecting entities based on movement can involve transmission circuitry configured to enable transmission of a stepped-frequency radar signal, an antenna, and receiving circuitry configured to generate data including information associated with frequency and phase shifts between the transmitted signal and the reflections of the transmitted signal. The system also can involve a processor configured to analyze the generated data to determine information associated with a moving object located at a side of a wall different than a side of the wall of which the system is located. The analyzing can involve compensating for the effect of motion of the system on the phase shifts between the transmitted signal and the reflections of the transmitted signal.

Abstract: A training set including a target object set and a clutter object set is accessed. It is determined that the training set includes multiple types of targets or multiple types of clutter. The target feature value of a type of target is compared with the clutter feature value. The type of target is associated with the non-target object based on the comparison. A classifier is trained using the target feature value and the clutter feature value of the associated type of target and the non-clutter object. A feature value associated with an unknown object is applied to multiple classifiers to generate a set of metrics for the unknown object. The metrics are aggregated into an overall metric. Whether the unknown object is included in the target set is determined based on the overall metric.

Abstract: Screening of items for the presence of contaminants, such as explosives residue, is accomplished by subjecting an item loaded into a pressure chamber to a pressure substantially in excess of atmospheric pressure conditions and rapidly decompressing the item to the ambient atmospheric pressure. The rapid decompression serves to scavenge vapors and particles from the exterior and interior of the item and any objects it contains. A sample of the vapors and particles removed from the item by the rapid decompression is sampled and is tested to determine whether a predetermined contaminant is present in the sample. Depending on the types of contaminants for which the sample is tested, it is possible to detect whether explosives, biological or chemical agents, and/or narcotics residues are present on or in the item being screened.

Abstract: In one general aspect, a sample area is energized. A thermal energy status of the sample area is monitored. The thermal energy status including at least one of a radiant energy and a temperature. A thermal signature of a region included in the sample area is determined based on the thermal energy status of the region. The thermal signature is analyzed to determine whether explosive particles are included in the region.

Abstract: An integrated mine detection system includes a ground penetrating metal detector and a ground penetrating radar detector. The integrated mine detection system includes an integrated search device housing a radio-wave transmitter of the radar detector and a coil of the metal detector. The radio-wave transmitter includes an antenna. The integrated search device includes a radio-wave receiver in the form of a pair of receiving antennas.

Abstract: A device includes a sensing element configured to produce a representation of an object in a space near the sensing element, an electronic storage comprising multiple representations, each representation being associated with a particular object, a communications interface, and a processor operable to receive the representation of the object in the space from the sensing element, compare the representation of the object in the space to the multiple representations stored in the electronic storage, determine that the representation of the object in the space is different from all of the multiple representations based on the comparison, identify the representation as a new representation based on the determination, and cause the new representation to be available to a data site through the communications interface. The device also may obtain a new representation from the data site.

Abstract: In one aspect, an apparatus includes a head configured to receive a pad for sampling explosive residue on a surface and a feedback system coupled to the head. The feedback system is configured to indicate when a pressure applied by the head is greater than a minimum threshold value. In another aspect, an apparatus includes a head configured to receive a pad and rotate to apply a shear force to the pad for sampling explosive residue on a surface. The apparatus includes a feedback system coupled to the head, which is configured to restrict the shear force applied by the head to be within a predetermined range. In another aspect, a method includes applying pressure to a pad to sample explosive residue on a surface, sensing the pressure applied to the pad, and providing an indication of when the pressure applied to the pad is greater than a threshold value.

Abstract: Screening an item for prohibited material may include multiple pressurization and rapid depressurization cycles. Screening an item for prohibiting material may include a pressurization chamber including one or more items to be screened for prohibited material and one or more filler objects.

Abstract: An explosive detection system includes an unmanned vehicle and a manned vehicle. The unmanned vehicle includes a reflector. The manned vehicle includes a ground penetrating radar. The manned vehicle also includes electronics configured to process radar signals that are reflected by the reflector to detect an explosive device. The manned vehicle follows the unmanned vehicle.

Abstract: An integrated mine detection system includes a ground penetrating metal detector and a ground penetrating radar detector. The integrated mine detection system includes an integrated search device housing a radio-wave transmitter of the radar detector and a coil of the metal detector. The radio-wave transmitter includes an antenna. The integrated search device includes a radio-wave receiver in the form of a pair of receiving antennas.

Abstract: A particle-harvesting material includes a flexible, reusable, and thermally conductive material including a rough surface having dimples of a size within a first range of sizes, a microstructure including interstices of a second range of sizes, the second range of sizes including sizes smaller than the first range of sizes, and an etched portion on the rough surface configured to attract particles upon contact between the particles and the etched portion.

Abstract: An explosive detection system includes an unmanned vehicle and a manned vehicle. The unmanned vehicle includes a reflector. The manned vehicle includes a ground penetrating radar. The manned vehicle also includes electronics configured to process radar signals that are reflected by the reflector to detect an explosive device. The manned vehicle follows the unmanned vehicle.

Abstract: In one aspect, an apparatus includes a head configured to receive a pad for sampling explosive residue on a surface and a feedback system coupled to the head. The feedback system is configured to indicate when a pressure applied by the head is greater than a minimum threshold value. In another aspect, an apparatus includes a head configured to receive a pad and rotate to apply a shear force to the pad for sampling explosive residue on a surface. The apparatus includes a feedback system coupled to the head, which is configured to restrict the shear force applied by the head to be within a predetermined range. In another aspect, a method includes applying pressure to a pad to sample explosive residue on a surface, sensing the pressure applied to the pad, and providing an indication of when the pressure applied to the pad is greater than a threshold value.

Abstract: A device includes a compressible conductive element including a first end and a second end, and an adjustment element coupled to the compressible conductive element, the adjustment element configured to adjust the compressible conductive element to a state of compression between an uncompressed mode and a compressed mode. The compressible conductive element is configured to couple to a source of electrical current at the first end and to radiate electromagnetic energy from the second end.