A new device detects the heartbeat and respiration of victims trapped in rubble or disaster debris, and reduces the time required to initiate a rescue. Searchers would like to distinguish live victims from those who have died recently and to distinguish humans from animals. In addition to search and rescue, there are other uses for the device that can detect multiple humans from a distance, and with material between the device and the humans.
This innovation uses continuous wave (CW) microwave radar to detect small motions due to breathing (about 1 cm) and heartbeats (about 1 mm) that can be detected amid the signal reflected from the non-moving rubble and background. The dynamic range of the receiver is improved by feeding an adjustable sample of the transmitted signal that is subtracted from the received signal, cancelling out the non-moving signals from the clutter. The cancellation signal is adjusted automatically to reduce the fixed clutter signal.
Changing the operating frequency of the radar systematically allows improving the range resolution of the measurement, allowing rejecting targets that are at distances more or less than expected. Signal processing can be used to separate multiple targets because multiple victims have different heartbeats at different rates.
Multiple radar units with multiple antennas can be used to look in different directions simultaneously, so that the position of the victim can be determined, and signals that originate from outside the rubble, and are just reflected, can be rejected. A colocated video camera is used to show the user where the antenna(s) are pointed, and to assist in selection of a suitable beamwidth, by displaying a graticule or shaded area on the image to indicate the currently selected antenna pattern. An integral GPS receiver provides time synchronization among multiple cooperating units, and provides a reliable time and position “stamp” for recording purposes. A wireless network can be used to interconnect multiple radar units, support multiple users, or connect to additional storage or signal processing computational resources.
The techniques developed here have applicability to non-life-sensing applications. The same design can serve as a high-resolution, small-form-factor radar that could probe for soft spots or holes ahead of a rover. The small, modular design lends itself to installing on an unmanned aerial vehicle (UAV), or a constellation of UAVs to scan large areas. While the present implementation is tailored to human vital sign monitoring, the basic hardware and software architecture lends itself to many high-resolution radar applications.
This work was done by James P. Lux, Vaughn P. Cable, Salman Haque, Michael R. McKee, Hirad Ghaemi, and Richard Kalantar Ohanian of Caltech for NASA’s Jet Propulsion Laboratory.
In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to:
Innovative Technology Assets Management
JPL
Mail Stop 321-123
4800 Oak Grove Drive
Pasadena, CA 91109-8099
E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
Refer to NPO-49108.
This Brief includes a Technical Support Package (TSP).
Life-Detecting Radar
(reference NPO-49108) is currently available for download from the TSP library.
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Overview
The document outlines the development and application of the Life-Detecting Radar technology, a project initiated by the Jet Propulsion Laboratory (JPL) in collaboration with the Department of Homeland Security (DHS). The primary goal of this technology is to enhance search and rescue operations, particularly in disaster and emergency response scenarios. The DHS aimed for an "80% solution today" rather than waiting for a perfect solution over several years, recognizing that existing search techniques are not fully reliable.
The project began in April 2012, with prototype testing starting in April 2013. The radar technology utilizes microwave sensing to detect human vital signs, which is framed as a remote sensing challenge. The document emphasizes the limitations of current search methods, noting that while they can indicate the presence of individuals, they often struggle with accurately locating them amidst debris and clutter.
The radar's performance is influenced by its ability to penetrate obstacles, which can resemble fog or pebbled glass to the radar signals. The document mentions that with sufficient radar power and effective clutter cancellation, heartbeats can be detected from considerable distances. However, the accuracy of distance detection is limited to 20% of the range, with angular accuracy ranging from 20 to 30 degrees. This level of precision meets the needs of urban search and rescue operations during the "detect" phase of searches.
The document also includes contact information for key personnel involved in the project, such as Jim Lux from JPL and John Price from DHS, indicating a structured approach to collaboration and communication within the project.
Overall, the Life-Detecting Radar represents a significant advancement in technology aimed at improving the effectiveness of search and rescue missions, providing a complementary tool to existing methods rather than a complete replacement. The initiative reflects a commitment to enhancing national security and resilience through innovative technological solutions.
