EP1875266A1 - Reseaux de radars a faible cout et a haute performance - Google Patents

Reseaux de radars a faible cout et a haute performance

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Publication number
EP1875266A1
EP1875266A1 EP05735647A EP05735647A EP1875266A1 EP 1875266 A1 EP1875266 A1 EP 1875266A1 EP 05735647 A EP05735647 A EP 05735647A EP 05735647 A EP05735647 A EP 05735647A EP 1875266 A1 EP1875266 A1 EP 1875266A1
Authority
EP
European Patent Office
Prior art keywords
radar
processor
data
track
target
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP05735647A
Other languages
German (de)
English (en)
Other versions
EP1875266A4 (fr
Inventor
Andrew M. Ukrainec
Al-Nasir Premji
Tim J. Nohara
Carl E. Krasnor
Graeme S. Jones
Peter T. Weber
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sicom Systems Ltd
Original Assignee
Sicom Systems Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sicom Systems Ltd filed Critical Sicom Systems Ltd
Publication of EP1875266A1 publication Critical patent/EP1875266A1/fr
Publication of EP1875266A4 publication Critical patent/EP1875266A4/fr
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/04—Display arrangements
    • G01S7/06—Cathode-ray tube displays or other two dimensional or three-dimensional displays
    • G01S7/22—Producing cursor lines and indicia by electronic means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/66—Radar-tracking systems; Analogous systems
    • G01S13/72—Radar-tracking systems; Analogous systems for two-dimensional tracking, e.g. combination of angle and range tracking, track-while-scan radar
    • G01S13/723—Radar-tracking systems; Analogous systems for two-dimensional tracking, e.g. combination of angle and range tracking, track-while-scan radar by using numerical data
    • G01S13/726—Multiple target tracking
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/87—Combinations of radar systems, e.g. primary radar and secondary radar
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/003—Transmission of data between radar, sonar or lidar systems and remote stations

Definitions

  • This invention relates to land-based radar surveillance of wide areas or local sites. It also relates to radar detection and tracking and multi-sensor fusion.
  • Homeland Security refers to the goal of detecting and defending against threats to public safety posed by potential attack by hostile individuals or groups. Homeland Security applications for radar surveillance differ fundamentally from most military applications. The high price of military radars is justified by the critical and urgent need for protection in combat zones or near high-value assets. The price is affordable because the deployments are confined in time and/or space. Homeland Security, in contrast, deals with threats, such as terrorist attacks, that materialize infrequently and can occur anywhere. Surveillance to counter such threats must be deployed simultaneously across huge areas on a permanent 24/7 basis. Therefore, in the market for sensors used for Homeland Security surveillance, low-cost is not just a competitive advantage, it is a fundamental requirement.
  • Homeland Security includes such applications as border patrol, law enforcement, critical infrastructure protection (both corporate and public facilities), transportation security, port security and coastal surveillance. AU of these applications require cost-effective detection and tracking of small, fast, maneuvering, elusive targets. Targets of interest include (but are not limited to) small watercraft in littoral regions, and snowmobiles on snow or ice cover, or other vehicles. At the present time, low-cost radar systems suitable for these homeland security applications are not operational.
  • COTS off-the-shelf
  • a radar antenna and transceiver can be purchased for under $10,000, depending on the transmitter power and antenna selected.
  • These marine radars exhibit surprisingly good hardware specifications such as transmitter power, receiver characteristics and antenna pattern.
  • these radars deliver mediocre performance for our targets of interest because of their primitive signal processing. They are primarily used for detecting large vessels and shorelines for navigation and collision avoidance purposes.
  • a COTS marine radar with a digitizer board and a software radar processor that runs on a COTS personal computer (PC) can allow a marine radar to be adapted for other applications.
  • PC COTS personal computer
  • One vendor [Rutter Technologies, www.ruttertech.com] has developed a radar processor for such a system [the Sigma S6 Processor] where the radar processor is tuned for detecting slow-moving floating ice targets (such as ice bergs or bergy bits) in the sea by using scan-to-scan integration techniques over time frames of 20 seconds to 160 seconds (to improve signal to clutter ratio (SCR)) combined with an alpha-beta tracker designed for non- maneuvering targets.
  • SCR signal to clutter ratio
  • This system has been designed for maritime operation on-board a vessel or moored platform and hence does not deal with the formation of radar networks, does not solve the small-RCS, fast, maneuvering target problem, and does not provide low- cost of operation since an operator is needed for each system. In addition, alerts are not automatically provided to remote users for unattended operation.
  • the present invention concerns radar surveillance networks applied to homeland security and avian radar applications.
  • the invention aims to provide a land-based, radar system that is low-cost and high-performance for Homeland Security, BASH and NRM applications.
  • the invention contemplates sophisticated radar signal and data processing algorithms that can reliably detect and track small, low-RCS, maneuvering targets, including small watercraft, snowmobiles, birds and aircraft, in dense target and clutter environments.
  • the present invention more particularly involves a low-cost, high performance radar sensor that can be networked with other like and dissimilar sensors to form low-cost, high- performance radar networks with situational awareness and wide-area coverage.
  • the invention seeks to use sophisticated radar processing combined with spatial diversity (associated with the location of radar sensors making up a radar network), which allows the performance of a low-cost, noncoherent radar system to approach that of much more expensive coherent radar systems.
  • the present invention aims to take advantage of standardized COTS technologies to the maximum extent possible to keep the system cost low and to provide for low life cycle costs associated with maintainability, upgrade ability and training.
  • the intent is to use COTS marine radars as the radar sensor in order to minimize sensor costs.
  • the radar sensors and systems are software-configurable so as to allow them to be easily adapted for different applications. Operator interaction is minimized in order to reduce the cost of operation.
  • the present invention additionally contemplates that the radar sensors and system can be controlled remotely, that the system supports remote users with different user requirements, and that the system can provide automated threat detection and issue alerts to local and remote users.
  • the present invention intends that radar target data are geo-referenced using a geographic information system (GIS) so that target data is tagged to earth co-ordinates and target dynamics including speed and heading are provided.
  • GIS geographic information system
  • the present invention further intends that the radar system incorporates features that efficiently support research and development and off-line analysis, allowing for example, target behavior to be studied so that target classification algorithms can be developed, or allowing target data to be studied and replayed after the fact, to assist, for example, in the prosecution of terrorists.
  • the present invention relates to the design of a low-cost, high-performance, land-based radar sensor and a radar network consisting of one or more of these radar sensors designed for homeland security and avian radar applications.
  • a feature of the present invention is the preferred use of COTS marine radars to provide economical antennas and transceivers that operate at X-band and S-band.
  • COTS marine radars exhibit surprisingly good hardware specifications such as transmitter power, receiver characteristics and antenna pattern.
  • the first part of our invention is to create an inexpensive radar sensor with high performance by integrating a sophisticated radar processor with COTS marine radar equipment.
  • the radar processor itself incorporates sophisticated algorithms and software that runs preferably on COTS personal computers (PC) to keep costs down.
  • PCs COTS personal computers
  • targets of interest include small watercraft, snowmobiles, and birds. These small, fast moving and maneuvering, non- cooperative targets have low (and fluctuating) radar cross-sections (RCS), and compete with ground (e.g. land, snow, ice cover, urban features), water and weather clutter.
  • RCS radar cross-sections
  • COTS marine radars are designed for navigation and recreational use and, as such, have low small-target detection sensitivity. The presence of many friendly targets further complicates matters and the tracking circuits included with these radars are completely inadequate for our targets of interest. To detect these small targets with these marine radars, surveillance operators would need to observe the display over several consecutive radar scans in order to begin to assess the situation at hand.
  • the radar processor of the subject invention incorporates a detection processor, a track processor, and a display processor.
  • Prior art processors have used significant amounts of scan-to-scan integration to increase the SCR and thereby improve detection sensitivity for small, slow- moving targets such as ice bergs, bergy bits, and capsized vessels or persons-in-water. These prior art systems exploit the fact that the radars are mounted on vessels and that sea clutter decorrelates over a relatively short time.
  • Scan-to-scan integration is not applicable to the fast-moving targets of interest of the present invention for two fundamental reasons: 1) the targets move out of the radar resolution cell due to fast movement, and 2) the land clutter that dominates detection due to the fact that the radar sensors are land-based does not decorrelate as quickly as sea clutter. As a result, a different approach must be adopted to improve * detection sensitivity. Rather than emphasize the steady ground returns with scan-to-scan integration, they are preferably removed with an adaptive clutter map. This is an important part of pre-detection radar processing when detecting in and around ground clutter. Ground clutter usually originates through mainbeam illumination when the antenna beam is pointed horizontally or looking down from a tower.
  • the detection processor of the present invention produces detections (also called plots) by setting lower detection thresholds than conventional processors, and thus is able to detect smaller targets.
  • the consequence of using lower detection thresholds is that an undesired, higher false alarm rate results, particularly due to the strong clutter residual in the vicinity of the land-based radars used in the present invention.
  • the track processor of the present invention depends on sophisticated association and track filtering algorithms that are designed to handle both the high false alarm rate and maneuvering targets. These approaches are unique to the present invention.
  • the plot-to-track association algorithm provides means to resolve ambiguities produced by multiple targets, missed detections, false alarms, and maneuvering targets, whereas the track filtering algorithm provides high quality estimates of target dynamics for the association algorithms and for the display processor. While the track filtering algorithm performs well with non-maneuvering targets, it uses special algorithms to handle maneuvering targets and this feature is unique to the present invention.
  • the track processor preferably uses a sophisticated plot-to-track association algorithm called MHT [D.B.Reid, "An algorithm for tracking multiple targets", IEEE Transactions on Automatic Control, vol. AC-24, no. 6, Dec. 1979, pp.
  • IMM filtering Interacting Multiple Model (IMM) filtering [G.A.Watson and W.D.Blair, "IMM algorithm for tracking targets that maneuver through coordinates turns", Proceedings of the SPIE (Society of Photo-Optical Instrumentation Engineers, vol. 1698, Signal and Data Processing of Small Targets, April 20-22, 1992, pp. 236-247].
  • SPIE Society of Photo-Optical Instrumentation Engineers, vol. 1698, Signal and Data Processing of Small Targets, April 20-22, 1992, pp. 236-247.
  • this invention includes schemes wherein the association algorithm is replaced by alternate techniques known to those skilled in the art and described in the literature including [S.S.Blackman, Multiple-Target Tracking with Radar Applications, Artech House, 1986], and wherein the track filtering algorithm is replaced by alternate techniques known to experts in the field and described in the literature including [S.S.Blackman, Multiple-Target Tracking with Radar Applications, Artech House, 1986]. Furthermore, this invention also includes schemes where the association and track filtering algorithms are combined into a single algorithm such as the Probabalistic Data Association algorithm and its numerous ⁇ variants [Y. Bar-Shalom, "Tracking methods in a multitarget environment: survey paper", IEEE Transactions on Automatic Control, vol. AC-23, no. 4, Aug. 1978, p ⁇ .618-626], [S.S.Blackman, Multiple- Target Tracking with Radar Applications, Artech House, 1986].
  • the second part of our invention is to network radars to a central monitoring station (CMS), and then integrate CMS
  • a single system is suitable for monitoring a geographically close group of sites or even a fairly large waterway. Multiple systems can be further networked together to provide integrated coverage of extended routes or border regions. Mobile systems are appropriate for monitoring regions needing more intermittent coverage.
  • fusion algorithms to further improve track quality will become apparent in the sequel.
  • the networking of a number of land-based radar sensors (each consisting preferably of a COTS marine radar combined with a sophisticated radar processor) and the fusion of their target data to provide improved tracking performance is a novel and unique feature of the present invention.
  • a major challenge of continuous, wide-area surveillance is the high cost of human effort to monitor sensor displays.
  • the networking of radar sensor target data to a CMS reduces the human costs significantly, since monitoring can be done far more efficiently at a single CMS than at the individual radar sensor sites.
  • further reductions in human operator costs are desirable, especially in applications such as border patrol, where vast regions of border have little or no target activity for extended periods of time.
  • another feature of the present invention is particularly valuable.
  • the track data produced by system of the present invention contains detailed (but compact) long-term behavior information on individual targets. For any given scenario, these data can be automatically tested for suspicious activity, in order to generate alerts to security personnel.
  • alerts can reflect complex behavior, such as collision predictions, origins and destinations of vessels, perimeter approaches or violations, density of traffic, etc.
  • the low- bandwidth track and alert information can be easily sent to central locations, and directly to end users, providing economical, effective monitoring.
  • a novel feature of the present invention is the provision of automated alerts to remote users who require them. This enables the radar surveillance system to run unattended with users alerted only when necessary. Furthermore, track displays can be provided to remote users to give them a clear picture of the situation when alerts arise.
  • the invention preferably exploits COTS communication technology to provide such remote alerts and displays inexpensively.
  • a novel feature of the present invention is the remote control of each radar sensor to reduce the human cost of operating and maintaining the radar network of radar sensors.
  • the applications towards which the present invention is directed require further research and development (R&D) in order to increase and establish knowledge concerning target behavior.
  • This knowledge can be used, for example, for automatic target identification.
  • Off-line analysis of target data can be used with ground truth data to better understand bird signatures, for example, which could then be used to develop bird identification algorithms.
  • knowing the kind of bird that is being tracked is valuable for forming an appropriate response (e.g. should aircraft delay take-offs and landings or make an evasive maneuver to increase safety).
  • target identification could be very useful in determining whether a real threat exists when a target approaches a security perimeter near some critical infrastructure. Another example would be to perform off-line statistical analyses of target data in order to learn routes and patterns characterizing criminal activity in border areas.
  • a novel feature of the present invention is the ability to continuously store complete target detection and track data over extended periods of time in order to support such R&D activities.
  • Another novel feature of the present invention is the ability to rapidly play back stored target data into the radar processor in order to study and analyze the data.
  • Prior art systems particularly those employing COTS marine radars) do not provide such support for R&D activities.
  • FIG. 1 is a block diagram of a radar sensor apparatus included in a radar surveillance system, in accordance with the present invention.
  • FIG 2 is a block diagram of a radar controller that may be incorporated into the radar sensor apparatus of Figure 1 , in accordance with present invention.
  • FIG. 3 is a block diagram of a remote controller for a Furuno FR2155BB radar system, in accordance with the present invention.
  • FIG 4 is a block diagram showing a radar network incorporating plural instances of the radar sensor apparatus of Figure 1, 2, and/or 3, in accordance with the present invention.
  • FIG. 5 is a block diagram of radar network architecture in accordance with the present invention.
  • Figure 6 is essentially a block diagram showing a central monitoring site or operations center using the radar network of the present invention.
  • the radar sensor apparatus 10 includes a radar device 12 that is typically noncoherent and transmits pulses of constant width at a constant pulse repetition frequency (PRF) at X-band or S-Band.
  • Radar device 12 typically has either a continuously rotating or sector scanning antenna 14.
  • Antenna 14 is elevated to be several meters above the area to be monitored, and has a detection range of several kilometers.
  • COTS marine radars typically have these characteristics and are preferred for the present invention due to their availability, low-cost, and good antenna and transceiver characteristics.
  • Radar device 12 takes the form of a marine radar.
  • a typical marine radar is noncoherent, transmits at X-band with 50 kW peak power, pulse repetition frequency (PRF) between 1 and 2 kHz and with pulse width between 0.1 and 1 ⁇ s. It has a 2 m antenna with a narrow azimuth beamwidth and a wide elevation beamwidth, rotates at 24 RPM, and has up to 165 km range.
  • a radar such as this retails for around $50,000. Marine radar configurations are based on choosing a peak ' power/maximum-range value and an antenna size. Radars with peak powers up to 10 kW typically retail for less than $10,000. The lower-power radars can be purchased for as little as two or three thousand dollars making them very cost effective.
  • a specialized antenna 14 it is important to use a specialized antenna 14 to meet requirements.
  • An avian radar application for example, often requires bird height information.
  • a typical marine radar antenna with a 20° elevation beamwidth does not provide accurate enough height estimates in these cases.
  • other antennas may be preferred.
  • a 4° pencil beam dish antenna is described that has been successfully tested in the field with an implementation of the radar sensor of the present invention. This antenna provides better height estimates of birds but its coverage is limited.
  • antenna 14 may be an elevation-monopulse antenna to provide simultaneously good height estimates with full coverage in elevation.
  • the present invention provides for the integration of such an antenna into the radar sensor apparatus 10. While a phased array antenna could be integrated into the radar sensor 10 of the present invention, it is not a preferred embodiment of the present invention due to the significantly higher cost anticipated for such an antenna. In addition, it is not clear that the volume search rate of such a two-dimensional antenna could satisfy target update requirements.
  • a digitizer 16 is connected to an output of marine radar device 12 for collecting radar video samples from each pulse, at sampling rates and over range intervals appropriate for the operational mode.
  • Digitizer 16 is preferably a PC card mounted on a bus of a computer 18, which is preferably a commercial off-the-shelf (COTS) PC.
  • the PC computer 18 can run any standard operating system, but preferably runs a Microsoft WindowsTM operating system.
  • the digitizer 16 itself is preferably a COTS product to further reduce the radar sensor cost.
  • the digitizer 16 preferably samples the radar video signal at 12- bits and operates in real-time.
  • the digitized signals are the full-bandwidth, unprocessed radar signals captured in real-time to create a fully digital radar sensor in which the radar's signal processing and operating characteristics are determined by a radar processor 20.
  • Radar processor 20 is implemented as generic digital processing circuits of computer 18 modified by programming, or configured by software, to accomplish the functions described hereinafter.
  • Radar processor 20 includes includes a detection processor or pit extractor 22, a multi-target track processor 24 and a display processor 26 all of which are preferably implemented in real-time by software that runs on the COTS PC 18.
  • the software is preferably written in C/C++, and possibly assembly, and uses multi-threaded programming to provide a highly responsive application as well as for computational efficiency.
  • the software also preferably exploits the Single Instruction Multiple Data (SIMD) capabilities of modern processors to considerably improve processing speed.
  • SIMD Single Instruction Multiple Data
  • Detection processor 22 declares the presence and location of targets preferably on each radar scan.
  • Track processor 24 sorts the time-series of detections (also called plots) into either tracks (confirmed targets with estimated dynamics) or false alarms.
  • the processed information produced by radar processor 20 can be presented to the operator on a local display 28 that is part of display processor 26. This information may include scan-converted video, target data including detection data and track data, maps, user data (e.g. text, push pins) etc.
  • Operator controls 30 may be local as well and provide a graphical user interface for the local user to control the operation of the radar processor 20.
  • the radar processor 20 performs radar signal processing functions known to those skilled in the art such as scan-conversion, adaptive clutter-map processing to remove ground and weather clutter, sector blanking to suppress detections in regions that are not of interest, constant false alarm rate (CFAR) processing, and digital sensitivity time control (STC). These functions may be included in either the detection processor 22 or the display processor 26, but preferably are included in both so that the user display can be optimized for the user while the detection processor can be optimized for detection and tracking performance.
  • radar signal processing functions known to those skilled in the art such as scan-conversion, adaptive clutter-map processing to remove ground and weather clutter, sector blanking to suppress detections in regions that are not of interest, constant false alarm rate (CFAR) processing, and digital sensitivity time control (STC). These functions may be included in either the detection processor 22 or the display processor 26, but preferably are included in both so that the user display can be optimized for the user while the detection processor can be optimized for detection and tracking performance.
  • PFA probability of false alarm
  • Conventional radars employing automatic detection and tracking algorithms typically set the detection threshold high enough to achieve a probability of false alarm (PFA) to 1 in 10 6 resolution cells or less. For a radar display extending 50 km in range with a 100 m range resolution and 1° azimuth resolution, this translates to about 1 false alarm every 5 scans or 12 seconds (typical marine radar scan rates are 24 RPM).
  • low detection thresholds are a special feature of the detection processor 22 and are used in order to increase the sensitivity of the radar, allowing smaller targets to be detected.
  • An unwanted side effect is that the false alarm rate increases substantially, making it more difficult for tracking to perform.
  • the PFA could drop 3 orders of magnitude from typical settings to say 10 "3 resulting in 180 false alarms per scan or 72 false alarms per second.
  • the track processor 24 preferably includes multiple hypothesis testing (MHT) tracking with interacting multiple model (IMM) extended Kalman filtering as described earlier, and which are further described in [D.B.Reid, "An algorithm for tracking multiple targets", IEEE Transactions on Automatic Control, vol. AC-24, no. 6, Dec. 1979, pp. 843-854], [G.A.Watson and W.D.Blair, "IMM algorithm for tracking targets that maneuver through coordinates turns", Proceedings of the SPIE (Society of Photo-Optical Instrumentation Engineers, vol. 1698, Signal and Data Processing of Small Targets, April 20- 22, 1992, pp. 236-247].
  • MHT multiple hypothesis testing
  • IMM interacting multiple model
  • the display processor 26 provides a real-time display.
  • a map is integrated with the radar display and provides a background on which is overlaid geo-referenced radar data, including target data (tracks and detections), target echo trails, as well as scan-converted radar video in the form of a PPI display.
  • GIS geographical information system
  • Cursor position in latitude and longitude or UTM coordinates is continuously read out in the status bar, and numerous display features common to marine radars such as electronic bearing lines and virtual range markers are available. Small symbols at the location where the threshold is exceeded indicate detections.
  • a history of detections from previous scans can be shown, with fading intensities indicating scan time (the current scan's detections are the brightest).
  • Tracks are indicated by a different symbol drawn at a target's current position with a line emanating from the symbol indicating the heading.
  • the operator can select any track on the screen, and the system will display target information such as position, speed, heading, track stage, track uncertainty, echo size and intensity.
  • target attributes can also be used for the study and classification of targets of interest, and for multi-sensor fusion.
  • Detection and track data are rich with target attributes that are available for viewing by the operator in real-time. At any instant in time, the track histories provide situational awareness of recent activity. Any suspicious behavior (e.g. perimeter crossings) can be recognized, and communicated to authorities.
  • the benefits of the low detection thresholds to improve small target detection sensitivity are demonstrated with real data in [Weber, P et al., Low-cost radar surveillance of inland waterways for homeland security applications, 2004 IEEE Radar Conference, April 26-29, 2004, Philadelphia, PA ] along with the ability of the track processor 24 to track reliably through target maneuvers without increasing track uncertainty.
  • Clutter-map processing is demonstrated in [Nohara, T J et al, Affordable avian radar surveillance systems for natural resource management and BASH applications, 2005 IEEE International Radar Conference, May 9-12, 2005, Arlington, VA] to reject ground clutter so that birds can be detected along with a specialized target echo trails display mode that is a feature of the present invention.
  • a feature of the digital radar processor 20 of the present invention is the implementation of automated alerts based on target behavior inferred from track data.
  • Target behaviors such as perimeter breach, collision prediction or any complex behavior can be defined.
  • security perimeters are preferably defined.
  • the radar processor determines when targets approach and cross these perimeters, and issues appropriate alert responses.
  • target detection, tracking and threat recognition algorithms are customized for specific threats and scenarios.
  • Alerts can include an audible alarm and display indication to an operator, or a transmitted message to a remote user. Transmitted messages are preferably communicated over a network to remote users using networking and communication methods and technology known to those skilled in the art.
  • alerts can be issued as text messages or e-mails directed to pagers, cell phones, personal data assistants, BlackberrysTM etc. using COTS technology. Alerts can minimize required operator resources even to the point of permitting some systems to run 24/7 unattended.
  • a recorder 32 shown in Figure 1 can store the received radar video samples onto disk or tape.
  • Target data including track data and detection data can also be recorded.
  • Target data is a more compact and convenient alternative to raw radar video and can easily be stored continuously, 24/7, without stressing the storage capacity of a COTS PC. These same data can be remoted over a network 34; full-fidelity raw video, however, generally requires very high-speed networks.
  • Target data on the other hand, can be handled on low-speed networks, including real-time distribution over COTS wireless networks and over the Internet through inexpensive COTS networking hardware.
  • the stored data (in either raw format or target data format) can subsequently be played back through any computer running the radar processor software; it is not necessary that it be connected to a radar.
  • Target data can be archived for longer-term investigations.
  • the recorder 32 stores target data in accordance with operator selections.
  • the recorder 32 supports continuous writing of target data directly to a database 36 (as well as to other file formats).
  • the database 36 can reside locally on the radar processor computer, as indicated by a phantom connection 38, on another computer on the network, or on both.
  • the database 36 is used preferably for post processing, for interaction with external geographical information systems (GIS) systems, for remote radar displays, for support for web services, and for further research and development (e.g. to investigate and develop target identification algorithms).
  • GIS geographical information systems
  • radar processor 20 can be controlled remotely over network 34 (schematically shown as a bus in Figure 1), when a network connection is available. Radar processor control functions are implemented preferably as a web service, or alternatively, by using a virtual network console (VNC) so that the PC keyboard (not shown) and display 28 of radar processor 20 can be run remotely.
  • VNC virtual network console
  • COTS VNC server software runs on the radar processor PC and client VNC software runs on the remote end of the network 34.
  • a virtual private network is preferably established using COTS technology known to those skilled in the art. In this manner, the radar processor 20 can be remotely controlled from anywhere on an established network, using COTS software and hardware.
  • VPN virtual private network
  • a feature of the radar sensor of the present invention is a radar controller 40 to control the marine radar through a network-enabled software interface.
  • the radar controller 40 includes hardware (e.g. switches, control codes, etc.) that integrates with the marine radar to replicate control signals provided by the radar manufacturer.
  • This hardware is controllable by software that preferably runs on a COTS PC, and may be the same COTS PC that houses the radar processor.
  • the software provides either a user interface or programmer's interface to control the aforementioned radar features.
  • the software can be accessed over a network (as illustrated in Figure 1) either as a web service or through a VNC connection as described earlier.
  • a novel feature of the radar controller 40 is its preferred use of the radar's own display 28 to confirm the radar state.
  • the radar's local display video schematically represented at 42, is captured preferably using COTS frame-grabber technology and made accessible remotely through the radar controller software. In this way, the remote user can use the software to change the radar's state and can confirm immediately that the state has changed as requested by observing the remoted radar display.
  • Figure 2 a block diagram of the radar controller 40 is shown.
  • the diagram shows two logical components, namely the radar controller 40 with interface 44, and the marine radar device 12.
  • the radar controller 40 is ideally composed of both COTS hardware and software with the addition of original hardware and software. Controller 40 utilizes a hardware and software interface customized for the particular radar type to be controlled. Where possible, the existing radar control is preserved so that the addition of the computer automation does not interfere with standard manual operation of the radar system.
  • the controller is connected to a power switch or relay 46 for enabling remote control of the power supply to radar device 12, and to a command combiner 48 for controlling data transmission functions and antenna range.
  • the interface 44 also includes a video splitter 50 and a video capture module 52 for capturing the radar's local display video 42.
  • FIG 3 shows a preferred implementation 54 of the radar controller 40 of Figure 2 as applied specifically to a COTS Furuno 2155BB radar system 56.
  • the controller 54 uses serial codes for a variety of functions and relay contact switches for other functions.
  • the emulation of other radar control functions may require the use of digital to analogue (D/ A) converters, analog to digital (AJO) converters, digital I/O or other conversion interfaces in order to enable computer control.
  • D/ A digital to analogue
  • AJO analog to digital
  • I/O digital I/O
  • XML Remote Procedure Calls XML-RPC
  • SOAP XML Remote Procedure Calls
  • a standard network transport protocol such as HTTP
  • FIG. 3 also depicts a Furuno processor 57, a Furuno keyboard 58 and an ancillary radar processor 60.
  • One or more radar sensor apparatuses 10 as described above with reference to Figures 1-3 can be connected to network 34 to distribute information to remote users.
  • the radar processor architecture supports real-time communication of target data to remote sites using low-bandwidth, COTS network technology (wired or wireless). Since the target data contain all of the important target information (date, time, position, dynamics, plot size, intensity, etc.), remote situational awareness is easily realized.
  • the all-digital architecture facilitates networking of radar target data and control functions to a central monitoring station (CMS) 60 ( Figure 4) to consolidate monitoring resources for an entire radar network, thereby minimizing operating cost and providing for low-cost, high-performance radar networks.
  • CMS central monitoring station
  • the use of open network protocols such as TCP/IP and HTTP allow the delivery of the radar data anywhere over the Internet.
  • XML-RPC software application programming interface
  • a web server is then used to provide a client interface to a remote user.
  • the web server functions as both a web client application to the XML-RPC server to perform the radar control functions, as well as a web server application to provide a user-friendly graphical interface to a remote user with a client web browser.
  • This same principle is applied to other radar data services, such as the web services server interface to a TCP/IP networked SQL database containing a repository of past and live real-time radar data.
  • FIG 4 shows a conceptual diagram of the computer radar network 34.
  • One or more radar sensors 10 send their target data to one or more CMS 60 (which could be co-located with any of the radar sensors 10).
  • the target data consists of detection data, track data and/or alerts.
  • Raw radar video data could also be sent to the CMS 60 in real-time if a suitable network was available, but preferably, target data is sent.
  • Other types of surveillance sensors e.g. sonar
  • the network 34 and its software are typically COTS.
  • the CMS 60 has a fusion/display processor 62 ( Figure 5) that processes, combines, displays and archives the data. Integrated tactical information, including displays and alerts, is provided.
  • Track and detection data from the separated radar sensors 10 may be fused to take advantage of their spatial diversity and improve the radar network performance beyond that of the radar sensors themselves using multi-sensor data fusion methods known to those skilled in the art. This takes advantage of the spatial diversity of the sensors, and improves the radar network performance beyond that of the radar sensors 10 themselves. Data can also be accessed and integrated from other private or public networks (e.g. military, NEXRAD) as well.
  • private or public networks e.g. military, NEXRAD
  • FIG. 5 shows a preferred embodiment where the radar network 34 is implemented via the global computer network 64 known as the "Internet", with only a single radar apparatus 10 shown.
  • the same configuration of radar processor 20 plus radar controller 40 (or 54) is replicated for other sites.
  • Each site is connected to the Internet network 64 using a firewall and router device 66. (It is not necessary to use the Internet 64 as part of the network; a completely dedicated or private network could obviously be used as well.)
  • This configuration enables each independent site to connect and send radar data continuously and in a real-time fashion to a remote radar data server 68 and to enter it into a common SQL database server.
  • a single SQL database server is capable of receiving radar data from multiple related Radar Processor sites simultaneously.
  • the centralized pooling of radar data from the multiple radar sites allows for integration or fusion of related radar data by the CMS Fusion/Display processor 62.
  • An example of this is the processing of radar target tracks that cross the radar coverage area scanned by the radar antenna 14 of physically adjacent or related radar sensors 10.
  • the use of a standard open high-performance networked SQL database server in the radar data server 68 further maximizes the flexibility in providing the data services to multiple
  • the asynchronous messaging within the SQL database allows the radar processor 20 to indicate when a new scan of data is available inside the database. This signals the fusion/display processor 62 of any CMS 60 to monitor a particular radar processor 20 to update its display in real-time with the latest data.
  • the CMS fusion/display processor 62 need not be local to the radar data server 68 and may be located anywhere on the network 34, whether realized via the Internet 64 or a private network (not separately illustrated). In addition to monitoring live radar data, the CMS 60 also provides the capability to play back past recorded radar data. 'The functionality is analogous to that of a COTS hard-disk based Personal Video Recorders (PVR) such as TiVO.
  • PVR Personal Video Recorders
  • the CMS 60 may similarly allow a user to:
  • a handheld remote control device similar to that of a PVR, VCR, or DVD player preferably provides the operator with a familiar human device interface.
  • Such high-performance features added to a radar network as described above are unique to the present invention, all at affordable cost by exploiting open and COTS technologies.
  • the network-enabled XML-RPC API of the radar controller 40 gives programmatic access to the radar by an engineering maintenance console 70 ( Figure 5). Operations across multiple sites may be scheduled ahead of time and executed remotely by software. An example of this is the scheduling of monitoring only during a nightly interval. Another example is the automated change of radar parameters during daytime monitoring.
  • the CMS fusion/display processor 62 shown in Figure 5 can fuse target data from a radar network 34 to enhance the performance of these noncoherent low-cost radar systems, and have them approach the level of more expensive coherent radar systems.
  • the richness of the target data available from each radar sensor apparatus 10 in the network allows much flexibility when such data is required to be combined or fused for a wide-area display.
  • the target data permits both contact (detection) and track-level combination of data.
  • the following (non-exhaustive) list provides some examples of possible fusion methods that may be applied to the available data:
  • Another significant feature of the present radar surveillance system is the ability to customize the level and extent of the integration and fusion available, which is achievable through the rich information that has been produced and recorded by the radar detection processor 22 and tracker processor 24.
  • FIG. 6 illustrates an example of a radar network 34 in accordance with principles elucidated herein.
  • Seven radar sensors 10 schematically depicted as antennas 14 are assumed to be geographically separated to cover a wide-area of surveillance. Land-based installations are assumed, and antenna towers are made high enough to reduce blockage to acceptable levels, but low enough to be cost-effective and covert.
  • Portable and mobile systems are also possible.
  • two CMS's 60 are shown, one indicated as a command and control CMS 60a and the other as a secondary operations center 60b.
  • Ten radar workstations 72 are shown in the one CMS 60a and a single radar workstation 74 in the other 60b.
  • Each radar workstation 72, 74 can run the CMS fusion/display processor to create an integrated tactical surveillance picture from target data associated with a particular radar sensor 10, or multiple radar sensors. These support multiple operators with specific missions.
  • a dedicated display processor 76 that provides a completely integrated tactical picture preferably using all of the available radar sensors 10 drives a large war-room type display.
  • Each radar workstation 72, 74 is a dedicated workstation or workstations 72, 74 could also serve as the engineering maintenance console 70.
  • Another novel feature of the present radar surveillance system is the provision of a remote integrated tactical display to a mobile user.
  • the law enforcement personnel are located on mobile vessels on the water border. Using their on-board marine radar provides little or no situational awareness for reasons described earlier. Furthermore, line of sight is extremely limited because of the low height of the marine radar above the water.
  • the law enforcement vessel receives an integrated tactical picture from the CMS 60 over a wireless network 34.
  • the law enforcement vessel has an on-board COTS PC running a remote CMS Display Client that provides the integrated tactical picture created by the CMS Fusion/Display Processor. Preferably, the vessel's current location is shown on the tactical picture via a GPS input.
  • the CMS 60 (or 60a, 60b) simply routes fused target data produced by the CMS fusion/display processor 62 over a wireless network 34 to the CMS Display Client.
  • the law enforcement simply routes fused target data produced by the CMS fusion/display processor 62 over a wireless network 34 to the CMS Display Client.
  • S vessel gains the benefit of the performance of the entire radar network. Even if only a single radar sensor 10 is available and the radar processor 20 remotes its target data to the CMS display client directly, the vessel will have the radar visibility of a land-based, tower-mounted marine radar and sophisticated processing that far exceed the capabilities of the on-board marine radar.
  • the display processor 26 includes the ability to overlay PPI radar video (with now ground clutter suppression) on top of a geo-referenced map. Since the radar sensors 10 are land-based, this overlay will immediately show the presence of ground clutter, or its absence due to blockage or shadowing. Wherever ground clutter is present and overlaid on the map, coverage is available, where ever it is not, coverage is not available (at least for targets low to the ground). Moving the radar around in a mobile vehicle (e.g. a truck with a telescopic mast) and creating these coverage maps in real-time is a convenient, efficient, and cost-effective way of sighting the radar sensors that will form a radar network.
  • a mobile vehicle e.g. a truck with a telescopic mast
  • One of the key features of the present radar surveillance system is the exploitation of COTS technologies to keep the radar sensors and radar network low-cost. Not only is initial purchase cost made affordable with this approach, but maintenance and replacement are also characterized by short lead times, multiple suppliers, and reasonable prices.
  • the systems in accordance with the present invention deliver high performance with features tailored to customer needs while minimizing the three major components of cost: purchase cost, maintenance cost and operational cost.
  • a final feature of the present radar surveillance system is its software re-configurability which permits extensive customization to adapt its features to specific applications other than those described herein, with reasonable levels of effort. This will permit access to smaller markets since minimum economic quantities of customized systems will be small.
  • the software platform architecture also permits upgrades, feature addition, and target market customization. Particular features of our invention have been described herein. However, simple variations and extensions known to those skilled in the art are certainly within the scope and spirit of the present invention.

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

Système de surveillance par radars en temps réel qui comporte au moins un appareil capteur radar terrestre non cohérent adapté pour détecter des cibles manoeuvrantes et des cibles de petite section transversale ou de surface équivalente radar faible. Ledit appareil capteur radar comporte un dispositif radar de marine, un numériseur connecté au dispositif radar de marine pour recevoir dudit dispositif des échantillons de signaux d'écho radar vidéo et un ordinateur programmé pour mettre en oeuvre un processeur radar configurable par logiciel produisant des données de cible comportant des données de détection et des données de poursuite, ledit ordinateur pouvant être connecté à un réseau informatique comportant une base de données. Le processeur est conçu pour transmettre au moins une partie des données de cible via le réseau à la base de données. La base de données est accessible via le réseau par au moins une application d'utilisateur qui reçoit des données de cible de la base de données, l'application d'utilisateur fournissant une interface d'utilisateur pour au moins un utilisateur du système.
EP05735647A 2005-04-20 2005-04-20 Reseaux de radars a faible cout et a haute performance Withdrawn EP1875266A4 (fr)

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GB2441247A (en) 2008-02-27
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WO2006110973A1 (fr) 2006-10-26
GB2441247B (en) 2009-03-25

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