Through-the-wall and Underground Imaging Radar
Problem Statement
As defined in the Joint Warfighter Science and Technology Plan, military operations on urbanized terrain (MOUT) “is the capability to operate and conduct military operations in build-up areas and to achieve military objectives with minimum casualties and collateral damage. MOUT includes nonlethal weapons, precise weapons, surveillance, and situation awareness via communications effective in urban areas. The armed services recognize the need for through-wall sensing technology in order to increase situation awareness as well as weapon effectiveness in urbanized terrain. DoD understands that currently, soldiers “are unable to communicate through walls and other obstacles and that the technology does not currently exist, nor does a breakthrough appear imminent, that will allow the non-line-of-sight transmission (through obstacles) of the large bandwidths needed to carry necessary information to the individual warrior. As the military adopts its training and doctrine to better suit urban warfare, it is working to emphasize the collection of intelligence about an area before troops are deployed. Additionally, the military recognizes that there is a need for further investment in sensors that are able to operate within the concrete confines of an urban environment.
There is a critical need to clandestinely determine the location, armament, and other tactical information on personnel and equipment inside buildings to increase the effectiveness and safety of military operations using a system capable of remotely "seeing through-the walls" at distances in excess of 100 m.
The “through-the-wall” system must be capable of operating day/night and all-weather conditions. The generation of exceptionally high-resolution microwave images with spatial resolution of 1.5 cm and better through variety of wall types including drywall, wooden wall, brick/adobe and concrete wall structure with or without rebar is needed for accurate and reliable identification of imaged targets. The minimum functionality includes the following:
1. determine if the room is occupied or not,
2. if occupied, determine location of occupants in room
3. determine if inhabitants are armed or not
4. determine the materials of construction
5. map the contents of the room (tables, file cabinets, locations of doors,
windows etc.)
Moreover, the goal is to reliably detect, localize and identify targets day/night and all-weather conditions from a variety of potential host platforms including UAV, helicopter and ground vehicle such as HUMMV, which requires lightweight (less than 30 lbs) and portable (less than 4 cubic feet) system. In order to reduce technology insertion risk, the initial host platform will be a ground vehicle.
In addition, there is a need for deep ground penetrating imaging system for detection and localization of mines, UXOs, underground bunkers and caves containing hostile subjects.
Who Can Benefit
As a part of the Multipurpose Security and Surveillance Mission Platform (MSSMP), the army contracted Sikorsky to build a small, autonomous UAV that had vertical take-off and landing (VTOL) capabilities. Sikorsky developed the Cypher, a UAV with a diameter of 6.5 feet that is powered by a 50-hp engine. Cypher has hovering capabilities, a three-hour flight endurance, a range of 25 km, and a ceiling of 8,000 feet. The aircraft can be controlled from an integrated mobile ground station, or can operate autonomously, navigating using GPS. Cypher’s abilities were demonstrated in a MOUT exercise at Fort Benning, GA, where the vehicle flew down streets, landed on roofs, placed various payloads in strategic locations, and searched and tracked man-size targets.
The Dragon Warrior is under development by the Naval Research Lab and the Marine Corps Warfighting Laboratory. The UAV is meant to be a HMMWV-transportable, VTOL UAV that can be used for Marine Corps missions, including urban reconnaissance. The Dragon Warrior is about 112 inches in length with a rotor diameter of 108 inches and an estimated endurance between 3 and 5 hours, depending on payload weight. The Marine Corps expects to field the system in FY 2005.
The Marine Corps is planning to test a personnel identification and location system developed by Aether Wire & Location in December 2004. The system was originally developed for MOUT applications, but it could be used in other areas such as the Army’s Future Combat System and Land Warrior programs, as well as applications sponsored by US Special Operations Command (SOCOM). The Marine Corps has drawn up a mission needs statement for a “rugged, inexpensive position-location device that allows individual personnel to determine and report their grid coordinates and elevation within buildings. Requirements include the ability to communicate location information to the individual carrying the device, even through walls, and to transmit this information to the command-and-control structure; low power consumption; and immunity from detection by enemy forces, and from multipath effects.
In the last few years US Army is being involved in building platforms and sensors to detect and localize targets, such as landmines, roadside bombs, underground bunkers and caves. In particular, their interest is to have a suitable lightweight and compact imaging sensor to be hosted by the Camcopter-small UAV, capable of lifting 65 lbs of payload.
Compact, exceptionally high-resolution microwave imaging system operating
in a transient (impulse) regime can be integrated on all of the above-mentioned
host platforms/systems to yield an enhanced capability for not only “seeing”
through-the-wall applications, but also for detecting roadside bombs, buried
mines and other underground facilities.
Baseline Technologies
Current approaches used for wall penetration include:
1. Ultrasound
2. Thermal (IR) imaging
3. LiDAR
4. Magnetic detection
5. Millimeter wave
6. X-ray
7. Radar, including UWB radar
List of strengths of the above approaches can be summarized as follows:
• Can “look” through sheet metal (Ultrasound)
• Good resolution (Radar)
• Detects metal (Magnetic)
• Can detect motion (Radar, Ultrasound, Millimeter wave)
while list of weaknesses in the above approaches is:
• Inadequate wall penetration (Millimeter wave, LiDAR, IR)
• Short range (Ultrasound, IR, LiDAR, Radar)
• Coarse resolution (IR, Ultrasound, Narrowband radar)
• Multi-path issue (All Radars)
• Expensive (X-ray)
• Regulatory issues-may interfere with public frequencies
ImpSAR
Eureka Aerospace is developing a "through-the-wall" imaging system capable of "seeing" through walls such as drywall, wooden wall, concrete wall and brick wall, using extremely high-resolution transient impulse Synthetic Aperture Radar (ImpSAR) system. The system is capable of remotely imaging targets such as man, weapons, file cabinets, tables etc on the "other" side of the wall, at large standoff distance. Click here to proceed to the detailed description of the technology applied to remote imaging applications and for more information on current state of development.
Technology Availability
The first operational ImpSAR system hosted by a ground vehicle will be available by July 2006. The pulser and impulse radiating antennas are available COTS. Currently Tektronix digitizing scopes are used to receive and sample the waveforms. However, stand-alone system will employ 6 GHz Analog-to-Digital converter (ADC), to be fabricated using commercially available fast chip processors. Eureka Aerospace has all the basic ImpSAR processing software for real-time image processing. More advanced signal/image processing codes, including specialized 2-D filters, polychromatic SAR algorithm and image display together with conformal impulse radiating antenna with duplexer will be developed during Phase III transition phase. Finally, Eureka Aerospace is exploring a teaming arrangement with Boeing Aerospace - potential prime to integrate ImpSAR system into an airborne platform (UAV), which may constitute appreciable additional funding opportunity.
ImpSAR Application Gallery
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Scanning for hidden explosives with ImpSAR |
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ImpSAR in action
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