The disclosure relates to a method for calibrating at least one signal and/or system parameter of a wave-based measurement system, in particular radar measurement system. At least one receiving unit for receiving signals and an object scene assume several spatial positions relative to each other assume, wherein a relative positioning of the several positions to each other is known or determined, and at these several positions the signals are coherently detected by the at least one receiving unit, whereby a set of several coherent measurement signals is formed.

Imaging systems and associated methods are described. According to one aspect, an imaging system includes an antenna array having transmit and receive antennas, the transmit antennas emit electromagnetic energy from a plurality of different positions about a target imaging volume and the receive antennas receive reflections of the electromagnetic energy at the different positions, a transceiver configured to control the emission of the electromagnetic energy and to generate radar data that is indicative of the reflections of the electromagnetic energy received via the receive antennas; and processing circuitry configured to focus the radar data to provide first focused data in a first dimension, to focus the radar data in a second dimension to provide second focused data, and use the second focused data to focus the radar data in a third dimension to provide third focused data comprising an image of the target imaging volume.

The present disclosure provides a method for surface wear inspection using millimeter wave radar. The system initially receives a plurality of uncompressed raw Synthetic Aperture Radar (SAR) images. Further, a plurality of reconstructed SAR images are generated based on the plurality of uncompressed raw SAR images using a variable focusing based Range Doppler Algorithm (RDA). Further, a master image and a slave image are selected from the reconstructed SAR images and corresponding anchor points are assigned. Further a plurality of fine level and coarse level shift coordinates are computed based on the corresponding anchor points. Further, a net shift value is computed based on the plurality of fine level and coarse level shift coordinates. The master and the slave images are aligned based on the net shift value and the interferogram is generated. The interferogram is further analyzed to profile the corresponding deformation pertaining to the surface under test.

Systems and methods for a radar system to produce a radar image of a region of interest (ROI). A set of antennas to transmit radar pulses to the ROI and to measure a set of reflections from the ROI corresponding to the transmitted radar pulses. A processor acquires an estimate of the radar image, by matching the reflections of the ROI measurements for each antenna. Determine a set of shifts of the radar image. Wherein each shift corresponds to an antenna, and is caused by an uncertainty in a position of the antenna. Update the estimate of the radar image, based on the determined set of shifts of the radar image. Wherein for each antenna, the estimate of the radar image is shifted by the determined shift of the radar image corresponding to the antenna, that fits the reflections of the ROI measurements of the antenna.

A synthetic-aperture radar device of the present invention is the one having: a focal point information storing unit storing a plurality of pieces of focal point information determining positions of focal points; an image reproducing unit reproducing each radar image corresponding to the plurality of pieces of focal point information stored in the focal point information storing unit from a reception signal of a radio wave applied from a moving platform to an observation target and reflected by the observation target; an index calculating unit calculating an index representing an image forming state of the radar image reproduced by the image reproducing unit for each predetermined area; and a synthesizing unit synthesizing the plurality of radar images on the basis of the index calculated from each of the plurality of radar images, enabling obtaining a clear radar image without using positional information of the observation target.

Described is a system for synthetic aperture radar (SAR) imaging. The system is adapted to reconstruct a set of images to generate a set of reconstructed SAR images, wherein at least some of the reconstructed SIR images have noise and contain glint. The reconstructed SAR images are then stacked into a matrix D, in which each column of the matrix is a reconstructed SAR image. Using sparse and low-rank decomposition on the matrix D, the system then extracts a clean background from the reconstructed SAR images and separates the noise and glint. Based on that, the system is operable to detect moving targets in sparse part S and issuing a notification of such a moving target.

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.

Whether or not motion compensation is necessary is determined for each of received radio wave signals acquired through observation on the basis of information on a difference between an planned trajectory and an actual trajectory of a platform (103), and a motion compensation process is performed on the received radio wave signals for which the motion compensation is determined to be necessary. An image generation process is performed on the received radio wave signals on which the motion compensation process has been performed and the received radio wave signals on which the motion compensation process has not been performed depending on the results of determination, so that a SAR image of an observation object is generated.

A multi-hypothesis spatially-variant autofocus system for processing and focusing radar images, such as synthetic aperture radar (SAR) imagery, is configured to compute phase corrections and apply multiple autofocus strategies to overlapping image tiles for progressively smaller image tile sizes. Correction factors for the image tiles may be selected on a per-tile basis based on various metrics. In some embodiments, one or more phase-gradient autofocus (PGA) algorithms may be applied to window-size weighted versions of the overlapping image tiles for the progressively smaller image tile sizes.

There are provided: a high-accuracy factor calculator for calculating, by a high-accuracy computation method, a distance R from a moving platform to a pixel position (a, b) within an observation target corresponding to an predicted position (x.sub.t, y.sub.t) and a phase factor A when a determination processor determines that an error is out of an allowable range; and a low-accuracy factor calculator for calculating, by a computation method with lower accuracy than that of the high-accuracy factor calculator (e.g., a computation method using an approximation algorithm), a distance R from the moving platform to the pixel position (a, b) corresponding to the predicted position (x.sub.t, y.sub.t) within the observation target and a phase factor A when the determination processor determines that the error is within the allowable range.