The radio system (10) comprises a waveform generator (1) alternately generating an FMCW wave representing a linearly frequency-modulated continuous wave for radar imaging and a CW wave representing a wave kept at a given frequency for measuring a velocity vector, an amplification chain (2), a set (4) of transmit antennas (41, 42, 43), a set (5) of receive antennas (51, 52, 531, 532), a set (7) of receivers (71-2, 731, 732), and a signal processor (9) implementing processing operations on FMCW signals received from the one or more lateral antennas (51, 52) of the set (5) of receive antennas (51, 52, 531, 532) and spectrally analysing CW signals received from the one or more lateral antennas (51, 52) and from the one or more ventral antennas (531, 532) of the set (5) of receive antennas (51, 52, 531, 532) so as to supply SAR images and components of the velocity vector of said airborne vehicle (20).

The various technologies presented herein relate to utilizing direction of arrival (DOA) data to determine various flight parameters for an aircraft A plurality of radar images (e.g., SAR images) can be analyzed to identify a plurality of pixels in the radar images relating to one or more ground targets. In an embodiment, the plurality of pixels can be selected based upon the pixels exceeding a SNR threshold. The DOA data in conjunction with a measurable Doppler frequency for each pixel can be obtained. Multi-aperture technology enables derivation of an independent measure of DOA to each pixel based on interferometric analysis. This independent measure of DOA enables decoupling of the aircraft velocity from the DOA in a range-Doppler map, thereby enabling determination of a radar velocity. The determined aircraft velocity can be utilized to update an onboard INS, and to keep it aligned, without the need for additional velocity-measuring instrumentation.

A method for operating a radar sensor in a motor vehicle, in which in a SAR measuring mode according to the principle of the synthetic aperture, objects, including stationary objects, are located with high angular resolution. The same radar sensor is operated in time-shifted manner or concurrently in the SAR measuring mode and in a Doppler measuring mode, the relative speeds of objects, including moving objects, being measured with a time resolution in the Doppler measuring mode that is greater than the time resolution in the SAR measuring mode.

A radar image processing device is provided for generating a radar image from a region of interest (ROI). The radar image processing device receives transmitted radar pulses and radar echoes reflected from the ROI at different positions along a path of a moving radar platform and stores computer-executable programs including a range compressor, a graph modeling generator, a signal aligner, a radar imaging generator and a focused image generator. The radar image processing device performs range compression on the radar echoes by deconvolving the transmitted radar pulses and a radar measurement to obtain frequency-domain signals, generate a graph model represented by sequential positions of the moving radar platform and a graph shift matrix computed using the frequency-domain signals, iteratively denoise and align the frequency-domain signals to obtained denoised data and time shifts by solving a graph-based optimization problem represented by the graph model, wherein the approximated time shifts compensate phase misalignments caused by perturbed positions of the moving radar platform, and perform radar imaging based on the denoised data and the estimated time shifts to generate focused radar images.

A method for operating a radar sensor in a motor vehicle, in which in a SAR measuring mode according to the principle of the synthetic aperture, objects, including stationary objects, are located with high angular resolution. The same radar sensor is operated in time-shifted manner or concurrently in the SAR measuring mode and in a Doppler measuring mode, the relative speeds of objects, including moving objects, being measured with a time resolution in the Doppler measuring mode that is greater than the time resolution in the SAR measuring mode.

A method and a system for detection and synthetic aperture (SA) imaging of a target are disclosed. The method may include illuminating a scene with a search signal transmitted from a moving platform, receiving a search return signal from a target present in the scene, and estimating, from the search return signal, the range and the angular location of the target. The method may also include generating an SA transmission signal and a local oscillator (LO) signal with a time delay therebetween based on the estimated range, and illuminating the scene with the SA transmission signal pointed along an imaging direction based on the estimated angular location of the target. The method may further include receiving an SA return signal from the target, mixing the SA return signal with the LO signal to generate SA signal data, and generating an SA image of the target from the SA signal data.

A synthetic aperture radar (SAR) system and method of operation advantageously implements dynamic self-cueing or autonomous cueing of successive high-resolution SAR data collection based on previously collected wide-swath SAR data, for instance without the intervention of ground-based resources. For example, target detection may be performed on-board a spaceborne or airborne SAR platform using wide-swath SAR data acquired via a first beam at a first frequency band, the first beam pointed at a first angle relative to an along-track direction. Subsequent activities are cued by the platform based on the previously collected wide-swath SAR data. For instance, the SAR platform may cue subsequent acquisition of SAR data via a second beam at a second frequency band, the second beam pointed at a second angle relative to an along-track direction. The SAR platform may advantageously employ a multi-band SAR antenna.

Synthetic aperture radar (SAR) imaging systems that transmit repeated waveforms based upon pseudonoise sequences to generate SAR imaging data in accordance with various embodiments of the invention are disclosed. A synthetic aperture radar in accordance with one embodiment of the invention includes: a transmitter configured to transmit superchirps, where the superchirp is generated by convolving a kernel with a pseudonoise modulated impulse sequence having a flat power spectrum; a receiver configured to receive backscatters of transmitted superchirps and digitize the received backscatters; and signal processing circuitry configured to perform matched filtering on digitized backscatters.

A method and a system for detection and synthetic aperture (SA) imaging of a target are disclosed. The method may include illuminating a scene with a search signal transmitted from a moving platform, receiving a search return signal from a target present in the scene, and estimating, from the search return signal, the range and the angular location of the target. The method may also include generating an SA transmission signal and a local oscillator (LO) signal with a time delay therebetween based on the estimated range, and illuminating the scene with the SA transmission signal pointed along an imaging direction based on the estimated angular location of the target. The method may further include receiving an SA return signal from the target, mixing the SA return signal with the LO signal to generate SA signal data, and generating an SA image of the target from the SA signal data.

Multiple synthetic aperture radar SAR images of a target area on the earth are acquired using a satellite travelling in an orbit above the earth in a single pass of the satellite over the target area. In some methods, the data for each image is acquired from a different angle of incidence with respect to the target area. Then, the variation of quantity of backscattered radiation with respect to angle of incidence is analysed and used to identify matter imaged in a pixel or pixel group. In other methods, the data for each image is acquired from a different angle of incidence with respect to the target area, and the different angles of incidence are determined based on the specular reflection curve for a particular material. Then the quantity of backscattered radiation is analysed to determine whether the particular material is present based on the quantity of backscattered radiation. Extended dwell spotlight acquisition geometry may be used in which image data acquisition apparatus may be locked to illuminate same target as the satellite passes over the target for a period of for example 20 seconds.