Patent Application
20240248199
Border protection, customs and inspection against threats requiring development of mobile automatic detection technologies and devices rapidly as criminals and their techniques become more sophisticated. Digital transformation of industries and the growing automation of processes, there is now a need for simple, fast and accurate detection tools. Automatic object recognition technology can increase efficiency by offering faster analysis with a higher probability of detection. Threats vary according to the location and type. It may be narcotics or cigarettes in containers, weapons coming in. Threats vary again in landlocked countries, where cargo flow of goods may raise the risk of traffic and contraband coming through.
A method for detecting a concealed material in a target comprising a body and the concealed material, the method comprising: emitting radio frequency (RF) energy toward a direction of the target, capturing a signal corresponding to a scattered RF energy reflected from the target, measuring a first mean signal level in a first frequency band of the signal, measuring a second mean signal level in a second frequency band of the signal, and detecting the concealed material when the difference between the first mean signal level and the second mean signal level is above a threshold are presented in Prior ART FIG. 1, US 2016/0223666 A1. The emitter may emit RF energy of a horizontal or vertical polarity. The captured scattered RF energy reflected from the target may have a horizontal or vertical polarization. The first frequency band may be a frequency range in which the concealed material has a resonant RF scattering response, but in which the body lacks a resonant RF scattering response.
A multi-beam frequency-modulated continuous wave (FMCW) radar system designed for short range (<20 km) operation in a high-density threat environment against highly maneuverable threats. The multi-beam FMCW system is capable of providing continuous updates, both search and track, for an entire hemisphere against short-range targets. The multi-beam aspect is used to cover the entire field of regard, whereas the FMCW aspect is used to achieve resolution at a significantly reduced computational effort (PRIOR ART
Methods and apparatus for early detection and identification of a threat such as individuals carrying hidden explosive materials, land mines on roads, etc. are disclosed. One method comprises illuminating a target with radiation at a first polarization, collecting first radiation reflected from the target which has the same polarization as the first polarization, illuminating a target with radiation at a second polarization, and collecting second radiation reflected from the target which has the same polarization as the second polarization. A threat determination is then made based on the difference between the energy values of the first and second collected radiations. In other embodiments, the difference between energy values is used in conjunction with an evaluation of the returned energy in comparison with returned energy from other targets in order to additionally assess whether the primary target is a threat. In presented in Prior ART FIG. 3 U.S. Pat. No. 7,492,303 B1 apparatus can be mounted on mobile devices or positioned at fixed locations. The mobile mounted embodiments can be used by trucks and/or other vehicles to identify possible roadside threats or threats which may exist in the vehicle's direction of travel. Such threats include, e.g., above ground mines, improvised explosive devices and/or other types of weapons. In cases where hidden weapons on individuals is the primary concern, the display may limit the visual display of information to areas, e.g., cells of a scanned region, where a human presence is detected, e.g., through the use of thermal or other information Such an embodiment reduces clutter on the display and helps a user focus on potential threats.
Present invention related to radar or analogous systems specially adapted for specific applications for detection of concealed objects, e.g. contraband or weapons through wall detection. More particular to identification of targets based on measurements of radar reflectivity based on a comparison between measured spectrum components and known or stored values, analysis of echo signal for objects characterization by spectrum signature.
Multi-beam antenna array can cover of entire sky, but phase array with steering beam cannot provide non-interrupting communication with all signal sources simultaneously and scanning/switching beams are limiting communication line's budget. Phase of sinusoidal signal directly connected with frequency and phase correction needed to extend of frequency band. Trade between frequency band, gain and switching active time leads to interrupting line's budget and loos signal and/or data rate. Traditional phase arrays with scanning the volume of coverage giving limited dwell time on any given signal source. This limits the information that can be obtained for each source as well as limiting link budget [1,2].
Proposed nature inspired multi-beam antenna array architecture with multiple staring directional antennas will cover entire sky and allows real time recording of digital hologram. Integration of holographic non-scanning antenna system [1.2] with monopulse high directional accuracy method of signals processing directly on multi-beam multi-axis overlap antennas [3] and direct on antennas digitizing will provide fast threat detection, tracking and recognition.
This type of commercial multibeam wireless phased array antenna systems are requiring beamforming and beam shaping networks, which increasing mass and cost of system.
Phase array scattering approx. 80% of transmitting power to air because control of transmitting signals phase only without switching direction in separate antenna element does not mean control of direction of entire phase array, because every antenna element transmitting energy omnidirectionally. Antenna elements forming phase array must have as possible wide angle of view, means be omnidirectional. Efficiency of four beams antenna system too small because gain of each antenna formed beam four times smaller than possible corresponding to antenna array aperture. Gain of each beam equal to maximum possible gain divided to number of beams for omni-directional antenna elements.
Such multi-beam antenna array can provide up to 96 dual-polarized beams/sectors in 360° azimuth but only approx. 120 degrees by elevation because plane panel surface.
True antenna system capacity multiplied by number of beams, but limited by frequency bands because electronic scanning system, or phase array is frequency dependent. Phase directly connected to frequency and bandwidth can be extended by trade with gain, direction limit and switching active time only.
Fixed beams with fixed direction cannot provide adaptation of signal to noise ratio without reference channel.
Array of directional antennas with overlap antenna patterns and multi-channel signal's processing provides higher direction-finding accuracy, direction adjustment possibility and faster signals processing Stephen E. Lipsky [3].
Fly Eye antenna system described in [4] by Pavlo A. Molchanov can provide 360 degree coverage by azimuth and elevation, continuous higher gain and capacity in each channel, one-step direction adjustment and adaptation to transferring media and multi-band work limited by directional antenna bandwidth only.
An objective of the present invention is development of radar for automatic detection and identification concealed objects based on integration of holographic non-scanning antenna array with monopulse high directional accuracy method of fast direction finding and direct digitizing of signals on each directional antenna relatively to processor sampling signals and real time processing of three-dimensional interferograms in time and frequency domains. Radar comprising multiple directional antennas coupled with signal conditioning circuits and SDR (Software Defined Radio) arranged as integrated transceiver antenna modules connected to multi-beam signal processor by digital interface arranged as universal serial bus or microwave and/or fiber optic waveguides or wirelessly. It allows distribution of integrated transceiver antennas modules around vehicle perimeter or between drone's swarm and provides additional system protection against jamming, spoofing or EM pulse. Transformation and processing of received different polarization signals in time domain, frequency domain and multi-axis space domain decreasing false errors probability and enhance identification by spectrum signature.
Proposed multi-channel continuous wave radar for detection of concealed objects configured to transmit and receive horizontally, vertically or circular polarized waveforms. Radar comprising as minimum one transceiver antenna module with multiple directional antennas wherein antenna patterns overlap in one or more directions for creating monopulse subarrays continuously covering of entire area of observation or subdivided sector. Each directional antenna formed by subarray of antenna elements arranged in module volume, on module surface or combined. Said transceiver antenna module comprising as minimum one transmitting chain including phase lock loop signal generator and controllable power amplifier coupled with directional antenna and connected to software defined radio. Also said transceiver antenna module comprising multiple conditioning receiving chains including voltage or current limiters, anti-aliasing circuits wherein each conditioning receiving chain coupled with directional antenna and connected to software defined radio. All transceiver antenna modules connected to multi-channel signal processor by digital interface arranged as universal serial bus (USB) or microwave and/or fiber optic waveguides. Multi-channel signal processor comprising memory, monopulse processor, objects identification means, and synchronization means. Memory arranged for storing executable instructions and for separate processing of amplitudes, phases, frequency components shift of signals in transmitting and receiving chains. Monopulse processor arranged for simultaneous multi-axis processing of all signals in receiving chains for calculating objects azimuth and range as ratio of amplitudes and/or phase shift of signals, one-iteration adapting to decrease transferring media influence to receiving chain parameters by phase shift in subarray of neighboring directional antennas with overlap antenna patterns. Objects identification means arranged to transform three-dimensional interferogram from time domain to frequency domain, creating spectrum signatures and identification of objects. Synchronization means arranged for synchronizing transmitting, receiving chains and software defined radios with multi-channel signal processor time. Plurality of multi-beam antenna array modules can be distributed by some order on carrier/satellite, vehicle or distributed between swarm or constellation of carriers/satellites to cover entire sky or area of observation.
In some embodiment said multi-channel continuous wave radar transceiver antenna module can be arranged in concave, convex, cylindric full/hemi sphere shape consisting of plurality of antenna elements which forming directional antennas.
Transmitting and receiving chains and multi-channel signal processor can be arranged for simultaneous transmitting, receiving, and processing signals on a few different frequencies (multi-frequency signals) and comprising corresponding arranged directional antennas, anti-aliasing circuits and filtering means in each transmitter and receiving chain.
In some embodiments of multi-channel continuous wave radar transmitting and receiving circuits and signal processor can be arranged for simultaneous transmitting, receiving, and processing different modes and different waveforms signals, such as communication, navigation, control (multi-mode, multi-function signals) and comprising corresponding arranged directional antennas, anti-aliasing circuits and filtering means in each transmitter and receiving chain.
Multi-channel continuous wave radar comprising receiving circuits and multi-channel signal processor can be arranged for simultaneous processing received signals for detection direction of arriving of jam and/or spoof signals and comprising corresponding arranged analog and digital filtering and/or switching protection means in each receiving chain and in each channel of signal processor.
Second embodiment of multi-channel continuous wave radar for detection of concealed objects arranged as multi-static radar with one or a few transmitting modules distributed and multiple receiving only antenna array modules with automatic objects recognition and wirelessly connected with operator. Multi-static radar comprising as minimum one transmitter module comprising transmitting chain including phase lock loop signal generator, and controllable power amplifier coupled to as minimum one antenna continuously covering of entire area of observation or subdivided sector and connected by digital interface to wireless transceiver module and INS/GPS module. Multiple multi-beam receiver antenna modules comprising multiple directional antennas wherein antenna patterns overlap in one or more directions for creating monopulse subarrays continuously covering of entire area of observation or subdivided sector and comprising multiple conditioning receiving chains including voltage or current limiters, anti-aliasing circuits wherein each conditioning receiving chain coupled with separate directional antenna and software defined radio. Each directional antenna formed by subarray of antenna elements arranged in module volume, on module surface or combined. All multi-beam receiver modules connected to multi-channel signal processor, wireless transceiver module and INS/GPS module by digital interface arranged as universal serial bus (USB) or microwave and/or fiber optic waveguides. Multi-channel signal processor comprising memory, monopulse processor, objects identification means and synchronization means.
PRIOR ART FIG. 1 illustrates of the radar for detection of a concealed object on a body.
PRIOR ART FIG. 2 shows known short range point defense radar.
PRIOR ART FIG. 3 shows method and apparatus for detection threats using radar.
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Application of antenna array for detection and recognition of underground concealed object by monopulse method is shown in
Application of antenna array for through wall detection of concealed object by proposed method is shown in
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Diagram in
First embodiment of multi-beam transceiver antenna module is illustrated in
In some embodiment said multi-channel continuous wave radar transceiver antenna modules 701 can be arranged in concave, convex, cylindric full/hemi sphere shape consisting of plurality of antenna elements which forming directional antennas.
Transmitting 707 and receiving 709 chains and multi-channel signal processor 711 can be arranged for simultaneous transmitting, receiving, and processing signals on a few different frequencies (multi-frequency signals) and comprising corresponding arranged directional antennas, anti-aliasing circuits and filtering means in each transmitter and receiving chain.
In some embodiments of multi-channel continuous wave radar transmitting 707 and receiving 709 circuits and signal processor 711 can be arranged for simultaneous transmitting, receiving, and processing different modes and different waveforms signals, such as communication, navigation, control (multi-mode, multi-function signals) and comprising corresponding arranged directional antennas, anti-aliasing circuits and filtering means in each transmitter and receiving chain.
Receiving circuits 707 and multi-channel signal processor 711 can be arranged for simultaneous processing received signals for detection direction of arriving of jam and/or spoof signals and comprising corresponding arranged analog and digital filtering and/or switching protection means in each receiving chain and in each channel of signal processor.
Possible embodiment of passive receiver antenna module with ultrawide band directional antenna presented in
Proposed architecture of radar with multi-beam array of directional antennas allows to create multi-band antenna array module by arranging antennas of low frequency band and high frequency band in one integral module. Possible embodiment of multi-band directional antenna array with monopulse overlap antenna patterns is shown in
Diagram in
Subarrays of neighboring directional antennas overlapping in one-axes, quadrature or in multi-axes directions. Such set of directional antennas with overlap antenna patterns provides high accuracy monopulse direction finding, and using of some reference antennas provides reliable objects recognition and adaptation for suppression of noises and influence of transferring media parameters. Each directional antenna coupled with separate transceiver chain and can simultaneously use full channels capacitance for separate transmitting and receiving signals and non-interrupting work.
Processing of received signals including sequence of operations, which can be providing in parallel. Real time digitizing of received signals simultaneous providing directly on each antenna with overlap antenna patterns by analog-to digital converters in software defined radios. Creation of real time three-dimensional interferograms (real time digital hologram) of one or multiple.
Transferring of interferogram to multi-beam signal processor providing by digital interface.
Monopulse processing of received signals providing by calculating object azimuth and range as ratio of amplitudes and/or phases in separate overlap antennas within one or a few axes sub-arrays.
Fourier Transform of digital interferograms from time domain to frequency domain.
Creation of spectrum signatures of objects.
Objects identification by compare with a priory recorded in library spectrum signatures.
Mapping objects size, form and positions.
Generation of object detection alarm signal.
The time of signals processing is significantly decreased because signals from all satellites and other communication nodes processing simultaneously, even compare to processing digitally by switching virtual beamforming receiving signals. For example, a scanning system typically processes only one beam at a time, holographic staring systems processes signals by switching virtual beams and monopulse system processing all beams simultaneously.
Also, holographic systems transmitting more powerful signals, since a scanning system contains a high gain antenna on both transmit and receive, and in monopulse system transmitting power spreading inside relative wide space sector. From another side, high gain antennas in monopulse systems provides better gain and sensitivity than holographic systems, where usually applied array of omnidirectional antennas, which need provide wide area of observation for each antenna array element, and virtual set of receiving signals antennas activated for very short time for one separate node. Practically monopulse system will provide same gain and sensitivity of antennas, as scanning system with similar directional antenna.
Monopulse method provides better beam pointing accuracy of 2-3 orders then scanning systems. Synchronizing of signals directly in antennas provide high accuracy amplitude and phase measurement. Non scanning antenna array is phase/frequency independent and can be multi-frequency, multi-function. All receiving chains using ratio of amplitudes, phases and relative frequency components shift of signals for multi-axis signal processing. Monopulse processor can consist of filters and processing means for separation clutter signals, background noise, compensate moving errors.
