Abstract: A system, method and apparatus that includes two or more sensor nodes that obtain sensed data from a structure. A controller receives the sensed data from the sensor nodes, via a network formed by the sensor nodes and the controller. The controller controls functionality of each of the sensor nodes, controls time synchronization among the sensor nodes, detects information collected by the sensor nodes, and communicates, utilizing an M-ary time-reversal based protocol, the detected information using a planar surface of the structure as the transmission medium for elastic waves.

Abstract: A system, method and apparatus that includes two or more sensor nodes that obtain sensed data from a structure. A controller receives the sensed data from the sensor nodes, via a network formed by the sensor nodes and the controller. The controller controls functionality of each of the sensor nodes, controls time synchronization among the sensor nodes, detects information collected by the sensor nodes, and communicates, utilizing an M-ary time-reversal based protocol, the detected information using a planar surface of the structure as the transmission medium for elastic waves.

Abstract: Determining a speed and a range of an object by generating at least a first, second, and third interval-specific tone phase signals associated with at least three successive time intervals, wherein at least two of the generated and transmitted tones are different frequencies; determining at least a first, second and third interval-specific average phase value from the respective interval-specific tone phase signals; and then determining a range estimate of the object and determining a speed estimate of the object using at least two phase differences between the at least first, second and third interval-specific average phase values.

Abstract: Embedded piezoelectric sensors in large civil structures for structural health monitoring applications require data communication capabilities to effectively transmit information regarding the structure's integrity between sensor nodes and to the central processing unit. Conventional communication modalities include electromagnetic waves or acoustical waves. While guided elastic waves can propagate over long distances on solid structures, their multi-modal and dispersive characteristics make it difficult to interpret the channel responses and to transfer useful information along pipes. Time reversal is an adaptive transmission method that can improve the spatiotemporal wave focusing. The present disclosure presents the basic principles of a time reversal based pulse position modulation (TR-PPM) method and demonstrates TR-PPM data communication by simulation. The present disclosure also experimentally demonstrates data communication with TR-PPM on pipes.

Abstract: Embedded piezoelectric sensors in large civil structures for structural health monitoring applications require data communication capabilities to effectively transmit information regarding the structure's integrity between sensor nodes and to the central processing unit. Conventional communication modalities include electromagnetic waves or acoustical waves. While guided elastic waves can propagate over long distances on solid structures, their multi-modal and dispersive characteristics make it difficult to interpret the channel responses and to transfer useful information along pipes. Time reversal is an adaptive transmission method that can improve the spatiotemporal wave focusing. The present disclosure presents the basic principles of a time reversal based pulse position modulation (TR-PPM) method and demonstrates TR-PPM data communication by simulation. The present disclosure also experimentally demonstrates data communication with TR-PPM on pipes.

Abstract: A high resolution imaging system is used to detect and locate targets using time reversal in rich scattering environments, where the number of scatterers is significantly larger than the number of antennas. Our imaging system performs two major tasks by time reversal: clutter mitigation and target focusing. Clutter mitigation is accomplished through waveform reshaping to suppress the clutter returns. After the suppressed clutter is subtracted from the returned signal, a second time reversal for target focusing is performed. A final image is then obtained by beamforming.

Abstract: A method and apparatus for target focusing and ghost image removal in synthetic aperture radar (SAR) is disclosed. Conventional SAR is not designed for imaging targets in a rich scattering environment. In this case, ghost images due to secondary reflections appear in the SAR images. We demonstrate, how, from a rough estimate of the target location obtained from a conventional SAR image and using time reversal, time reversal techniques can be applied to SAR to focus on the target with improved resolution, and reduce or remove ghost images.

Abstract: A high resolution imaging system is used to detect and locate targets using time reversal in rich scattering environments, where the number of scatterers is significantly larger than the number of antennas. Our imaging system performs two major tasks by time reversal: clutter mitigation and target focusing. Clutter mitigation is accomplished through waveform reshaping to suppress the clutter returns. After the suppressed clutter is subtracted from the returned signal, a second time reversal for target focusing is performed. A final image is then obtained by beamforming.

Abstract: A method and apparatus for target focusing and ghost image removal in synthetic aperture radar (SAR) is disclosed. Conventional SAR is not designed for imaging targets in a rich scattering environment. In this case, ghost images due to secondary reflections appear in the SAR images. We demonstrate, how, from a rough estimate of the target location obtained from a conventional SAR image and using time reversal, time reversal techniques can be applied to SAR to focus on the target with improved resolution, and reduce or remove ghost images.