Vibrometry and sound reproduction of acoustic sources on moving platforms using …
US20240377241A1
Abstract
Systems and methods are provided for interrogating a moving acoustic source using radar and processing data using a selection of motion compensation techniques adapted from synthetic aperture radar (SAR) to remove the effects of linear and nonlinear target motion so that the range-Doppler map retains only vibration information in the Doppler dimension. Vibration and sound waveforms can thus be selectively reproduced at specific ranges directly from the radar baseband waveform, without the need for additional complex analysis or audio processing.
Description (excerpt)
CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. patent application Ser. No. 17/406,040, filed on Aug. 18, 2021, which claims the benefit of U.S. Provisional Patent Application No. 63/066,932, filed on Aug. 18, 2020, both of which are incorporated by reference herein in their entireties. FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT The United States Government has ownership rights in this invention. Licensing inquiries may be directed to Office of Technology Transfer at US Naval Research Laboratory, Code 1004, Washington, DC 20375, USA; +1.202.767.7230; techtran@nrl.navy.mil, referencing Navy Case Number 111980-US2. FIELD OF THE DISCLOSURE This disclosure relates to acoustics, including vibrometry. BACKGROUND Doppler radar provides an alternative to conventional techniques (e.g., accelerometers, lasers, microphones) for sensing small-scale vibrations. Predominant applications include the detection of vital signs, sound and speech, and structural vibration. Millimeter wave (MMW) vibrometry has received attention due to the widespread commercial availability of compact wideband transceivers at frequencies >60 GHz. Demonstrations are typically continuous wave (CW) at target distances ranging from a few millimeters to several meters. Airborne synthetic aperture radar (SAR) systems also show capability to observe the vibration of loitering targets as distortion to the radar image, implying potential to extend radar vibrometry to remote sensing applications given the maturation of techniques for accurate extraction and analysis of the vibration in real-world environments. Unfortunately, progress in Doppler vibrometry faces major limitations when it comes to the ability to sense the small-scale vibration of targets in motion. Radar sound/vibration reproduction results to-date require the targets under investigation to be conspicuously still. Although limited cyclic motion can be canceled at close range under constrained conditions using interferometric and multistatic techniques, such approaches greatly increase in cost and complexity for observation at longer standoff. Tracking people in motion implicitly requires the subjects to come to rest in order to detect and interpret vital signs, or else simply detect the presence of vibration without the ability to analytically reconstruct it. Airborne motion compensation techniques leveraging on-board inertial measurement and/or global navigation sensors can correct for the dynamics of the interrogating radar but not for the dynamics of the target. Widespread micro-Doppler techniques provide a useful time-frequency methodology for analyzing and separating components of cyclic motion superimposed on bulk target motion (e.g., the analysis of human gait, gestures, rotor blades, bird flight, boat dynamics, etc.), but the superposition of multiple sources of motion remains a difficult issue; a radar demonstration of small-scale vibrometry and sound reproduction for targets in large scale motion is lacking. BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES The accompanying drawings, which are incorporated in and constitute part of the specification, illustrate embodiments of the disclosure and, together with the general description given above and the detailed descriptions of embodiments given below, serve to explain the principles of the present disclosure. In the drawings: FIG. 1 is a diagram illustrating a stationary but vibrating target observed by a radar transceiver (TRX) along a line of sight in accordance with an embodiment of the present disclosure; FIG. 2 is a diagram showing Bessel harmonics observed from a stationary tuning fork vibrating at 125 Hz in accordance with an embodiment of the present disclosure; FIG. 3 is a diagram showing a harmonic of vibration observed in range-Doppler space in accordance with an embodiment of the present disclosure; FIG. 4 shows a moving platform, including a source of vibration, observed by radar transceiver in accordance with an embodiment of the present disclosure; FIG. 5 A is a flowchart illustrating an exemplary motion compe
Filing details
- Inventors
- Christopher T. Rodenbeck
- Assignee
- The Government Of The United States Of America, As Represented By The Secretary …
- Filed
- Jun 10, 2024
- Granted
- Application pending
Bibliographic data and excerpted text sourced from Google Patents (public record) as part of IP TechMatch's current-filings monitor. This filing is not part of the 2019 historical archive. For the authoritative full text, drawings, and legal status, see the source links above or consult USPTO records directly.