A satellite (140) for operation in orbit around the earth comprises an ADCS (131, FIG. 1) configured for mechanically steering the satellite in the azimuth direction to prolong a dwell time (1105), during which a selected target is visible from the satellite, as the satellite orbits over the target. A processor at the ground station may be configured to process raw SAR data from any of the satellites described here. The raw SAR data may be processed in a number of ways to provide image information including but not limited to forming multilook images, compiling video sequences and colour coding images.

Ground penetrating radar (GPR) measurements from a downhole well tool in a wellbore are obtained to identify length of fractures adjacent the wellbore. A ground penetrating radar transmitter of the downhole tool emits an electromagnetic pulse. The electromagnetic wave of the ground penetrating radar is diffracted on encountering an end or tip of a fracture, which acts as a secondary source. The diffracted signal is then collected by downhole receiver(s) of the downhole tool. Length of the fracture is determined based on the time of travel of the electromagnetic wave from its emission until its collection as a diffracted signal by the downhole receiver(s).

Ground penetrating radar (GPR) measurements from a downhole well tool in a wellbore are obtained to identify length of fractures adjacent the wellbore. A ground penetrating radar transmitter of the downhole tool emits an electromagnetic pulse. The electromagnetic wave of the ground penetrating radar is diffracted on encountering an end or tip of a fracture, which acts as a secondary source. The diffracted signal is then collected by downhole receiver(s) of the downhole tool. Length of the fracture is determined based on the time of travel of the electromagnetic wave from its emission until its collection as a diffracted signal by the downhole receiver(s).

Ground penetrating radar (GPR) measurements from a downhole well tool in a wellbore are obtained to identify length of fractures adjacent the wellbore. A ground penetrating radar transmitter of the downhole tool emits an electromagnetic pulse. The electromagnetic wave of the ground penetrating radar is diffracted on encountering an end or tip of a fracture, which acts as a secondary source. The diffracted signal is then collected by downhole receiver(s) of the downhole tool. Length of the fracture is determined based on the time of travel of the electromagnetic wave from its emission until its collection as a diffracted signal by the downhole receiver(s).

A system and method for forming synthetic aperture radar images. Radar return pulses are grouped into sub-dwells, and their frequency content is separated into frequency sub-bands. A coarse image is formed for each sub-band/sub-dwell combination. The coarse images are iteratively interpolated to higher resolution and combined, to form a single high-resolution synthetic aperture radar image.

A vehicle FMCW Doppler radar system (3) and related method using transmitter arrangement (4), a receiver arrangement (7) and at least one control unit (15). The radar system (3) is arranged to transmit signals (11), to receive reflected signals (12), and to obtain a plurality of measure results from the received reflected signals (12) along a main field of view (10) during at least two radar cycles where each radar cycle including a plurality of FMCW ramps. For each radar cycle, the control unit (15) is arranged to form a spectrum density map (30) from measuring points (14) along the main field of view (10), where each measure result results in a measuring point (14). The control unit (15) is arranged to combine at least two spectrum density maps to form a combined spectrum density map.

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.

A method for calculating a sensitivity of a displacement of Synthetic Aperture Radar (SAR) along line-of-sight direction to a slope gradient and a slope aspect is provided, comprising: obtaining SAR data and Digital Elevation Model (DEM) data covering slope bodies, and extracting a local incident angle of an image by utilizing a satellite side-looking imaging principle; carrying out geometric distortion on the slope bodies under ascending and descending orbits by utilizing the local incident angle, to obtain specific locations of geometric distortion areas under ascending and descending orbit; calculating sensitivities of detections to changes of the slope gradient and the slope aspect under ascending and descending orbits according to the extracted parameter information of the SAR satellite in ascending and descending orbits and satellite heights, and dividing a sensitivity distribution by combining the sensitivity and the specific locations of the geometric distortion.

Disclosed is a radar signal processing device 2 including frequency domain converters 201-1 to 201-M to convert raw data 11-1 to 11-M showing observation results acquired by a radar device 1 into those in a frequency domain, a signal restorer 202 to synthesize the raw data 11-1 to 11-M whose domain is converted into the frequency domain according to a least square method, a time domain converter 203 to return a signal series after synthesis to that in a time domain, and an image reproducer 204 to acquire a reproduced image 12 by performing image reproduction on the signal series whose domain is returned to the time domain.

A radar assembly for receiving signals at spaced frequencies from an unknown transmitting source comprising a receiver operative to receive signals; the receiver comprising a series of channels, each channel comprising a low pass filter configured to allow passage of a signal from an unknown transmitting source, an analog to digital converter configured to transform the signal from the unknown transmitting source to a digital signal, a Hilbert transform configured to transform the digital signal from the unknown transmitting source into a single sideband signal, a Fourier transform configured to transform the single sideband signal into a plurality of regularly spaced frequency samples, and an inverse Fourier transform for extracting regularly spaced frequency samples; whereby extracted pulses form a train of pulses that are inputted into an imager which utilizes synthetic aperture radar to form an image of the area of interest containing the unknown transmitting device and method thereof.