Existing implementations of continuous wave (CW) radar are not packaged appropriately for use as part of a heartbeat detection system for disaster search and rescue. They use separately packaged microwave components and laboratory test equipment, and require substantial skill to operate properly, including setup, calibration, and interpretation of the data.
A small integrated system uses modern monolithic microwave integrated circuits (MMICs) on a printed circuit board, integrated with a microcontroller that implements control algorithms and data acquisition, providing a standard serial or USB interface. The general-purpose microwave sensor module may be used for remote sensing of heartbeat and breathing, motion detection in general, as well as other applications where small displacements of a target need to be measured.
The module integrates a microcontroller with CW radar using homodyne detection. As in all homodyne receivers, the transmitted signal is used as a reference for the demodulation of the received signal. The module includes a capability to coherently combine an amplitude and phase-adjusted sample of the transmitted signal with the received signal to improve the dynamic range of the sensor by cancelling unchanging received signals. The microcontroller provides a variety of interfaces to a host computer or larger system.
The module has the ability to change the transmitted frequency, allowing use not only as a classic CW Doppler Radar, but also for a variety of swept, stepped, or variable-frequency applications. The module produces a stream of data samples derived from the detected signal via a variety of interfaces. Since the data processing is programmable, the data formats and rates can be easily varied, either by loading new software into the module, or by selecting from among options provided by a single program.
The initial implementation is approximately 3×3×1 in. (≈7.6×7.6×2.5 cm) and is designed for frequencies in the low microwave (2-to-4-GHz) range, but the design is general, and different parts could be used for other frequencies with appropriate changes in the details of fabrication (e.g. choice of substrate materials for loss). A smaller package is possible, as are lower power and mass.
This work was done by James P. Lux, Luis R. Amaro, Richard Kalantar O’Hanian, Raymond Quintero, Troy M. Torrez, Keizo Ishikawa, Michael R. McKee, Salman Haque, and Carson Umsted 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.
NPO-49416
This Brief includes a Technical Support Package (TSP).
Microwave Radar Sensor Module
(reference NPO49416) is currently available for download from the TSP library.
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Overview
The document titled "MICROWAVE SENSOR MODULE D-82018 – REV F" provides a comprehensive overview of a general-purpose microwave sensor module designed for various applications, including remote sensing of heartbeat and breathing, as well as motion detection. The module integrates a microcontroller with a continuous wave (CW) radar system utilizing homodyne detection, which allows for the coherent combination of transmitted and received signals to enhance the sensor's dynamic range by canceling out unchanging signals.
The architecture of the module includes several key components and functions. It features a radar transmitter, an adjustable signal cancellation path, and a sophisticated receive signal processing system that encompasses RF, analog, and digital processing. The document discusses design trade-offs made during the development of the module, ensuring optimal performance for its intended applications.
A significant aspect of the module is its microcontroller, which performs various additional functions. It includes an integrated DC to DC converter that regulates the power supply from a battery (9-18 volts) to a stable 5 volts for the RF circuitry. The microcontroller manages power consumption by controlling the RF circuitry's operation during measurements, thus enhancing energy efficiency. It also measures the unregulated supply voltage for diagnostic purposes and has an internal temperature sensor to implement temperature correction algorithms for frequency adjustments.
The document outlines the basic calibration and setup algorithms necessary for the module's operation, as well as ancillary sensing and control functions that enhance its versatility. The microcontroller provides multiple interfaces for communication with host computers or larger systems, facilitating integration into various applications.
Overall, the Microwave Sensor Module D-82018 represents a significant advancement in radar technology, offering a compact and efficient solution for detecting small displacements and monitoring vital signs. The document serves as a technical support package under NASA's Commercial Technology Program, aiming to disseminate aerospace-related developments with broader technological and commercial implications. It also includes contact information for further inquiries and emphasizes compliance with export regulations, ensuring responsible dissemination of the technology.
