A radar system for generating a radar image of a scene includes an input interface to accept radar measurements of a scene collected from a set of antennas with clock ambiguities, wherein the radar measurements are measurements of reflections of a radar pulse transmitted to the scene, a hardware processor configured to solve a convex sparse recovery problem to produce a radar image of the scene, wherein the convex sparse recovery problem matches a time shift of the radar measurements with a signal generated by propagation of the radar pulse through a radar propagation function of the scene, wherein the time shift of the radar measurements is represented as a convolution of the radar measurements with a shift kernel that is one-sparse in time, and an output interface configured to render the radar image.

The invention relates to a method and to an apparatus for determining a displacement vector field of a scenario, by a ground-based interferometric radar system operated in multi-bistatic mode and comprising a main radar transceiver device and at least one passive radar receiver device arranged at a predetermined distance from each other, in which the oscillators of the at least two radar are synchronized, in time and in frequency, in particular according to a signal coming from a global positioning system. The method provides a step of interferometrically determining at least one first displacement map and one second displacement map of the scenario between a previous time and a subsequent time, expressed in a global reference system and having each a plurality of pixels each associated to a respective domain of the scenario. The first and the second displacement maps comprise first and second displacement components of the pixel, respectively, along the line of sight of the main radar device, and along the bisectors of an angle between said line of sight and the line of sight of passive radar device, for each pixel. A step is then provided of combining the two displacement maps, more in detail, the first and the second component of each pixel, creating a displacement vector field of displacements occurred between the previous time and the subsequent time. The invention provides an apparatus much easier and less expensive than the prior art, in which a plurality of multi-monostatic, transceiving radar devices are used.

A phase synchronization method includes: pulse widths of first and second phase synchronization signals and starting time of transmission of first and second phase synchronization signals are determined, wherein starting time is located between two successive moments when radar signals are transmitted; first spaceborne SAR is controlled to transmit first phase synchronization signal to second spaceborne SAR according to pulse width and starting time of first phase synchronization signal; second spaceborne SAR is controlled, according to pulse width and starting time of second phase synchronization signal, to transmit second phase synchronization signal to first spaceborne SAR; compensation phase is determined according to peak phases of first and second phase synchronization signals received by second and first spaceborne SARs respectively; and phase synchronization compensation is performed, according to compensation phase, on radar signals received by first spaceborne SAR and second spaceborne SAR.

Range-compressed data are determined by range-compressing echo data, and are set as first data to be decomposed by first decomposition. Starting from n=1, iteration is performed as follows. nth data to be decomposed are up-sampled. nth decomposition is performed on the up-sampled data. Dependency on slant ranges between a reference point and sub-apertures before and after synthesis is determined. nth azimuth-synthesized data are acquired by performing, according to the dependency on the slant ranges, nth azimuth synthesis on data acquired by the nth decomposition. The nth azimuth-synthesized data are set as (n+1)th data to be decomposed by (n+1)th decomposition. The n is increased by 1. A next iteration is performed until the n reaches a positive integer N greater than 1. A focused image is acquired by performing azimuth focusing on the Nth azimuth-synthesized data by BP.

A constellation of satellites and associated methods for Earth Observation are disclosed. One method includes transmitting a set of at least four signals towards the Earth using a constellation of at least four satellites and receiving a set of at least four reflected signals from the Earth using the constellation. The method also includes analyzing, using a set of at least four signal analyzers, the set of at least four signals to generate a set of data. Each satellite in the constellation individually houses a signal analyzer in the set of at least four signal analyzers. The method also includes deriving the set of Earth observations using the set of data. Each satellite receives a signal in the set of at least four signals from every other satellite in the constellation.

A constellation of satellites and associated methods for Earth Observation are disclosed. One method includes transmitting a set of at least four signals towards the Earth using a constellation of at least four satellites and receiving a set of at least four reflected signals from the Earth using the constellation. The method also includes analyzing, using a set of at least four signal analyzers, the set of at least four signals to generate a set of data. Each satellite in the constellation individually houses a signal analyzer in the set of at least four signal analyzers. The method also includes deriving the set of Earth observations using the set of data. Each satellite receives a signal in the set of at least four signals from every other satellite in the constellation.

Synthetic aperture radar transmit and receive antenna systems and methods of transmitting and receiving radar signals are disclosed. In one embodiment, a transmit and receive antenna system includes a transmit antenna array configured to transmit a plurality of radio frequency transmit signals, the transmit antenna array including a plurality of patch antenna elements mounted to a printed circuit board, each patch antenna element belonging to a subarray, and one or more power amplifiers, each power amplifier feeding a subarray of the patch antenna elements, and a reflectarray receive antenna configured to receive radio frequency signals including a plurality of reflectarray antenna elements mounted to a printed circuit board, at least one antenna feed configured to receive radio frequency signals reflected from the plurality of reflectarray antenna elements, and at least one low noise amplifier electrically connected to the at least one antenna feed.

In some examples, a first plurality of independent waveforms can be generated and converted into a first plurality of independent transmitted radar signals transmitted towards a field of view using a transmitter array comprising a first plurality of transmitter antennas. Further, a second plurality of receive radar signals to the first plurality of independent transmitted radar signals can be received from the field of view using a receiver array comprising a second plurality of receiver antennas. The second plurality of receive radar signals can be combined to form a combined receive radar signal and a representation of one or more areas of interest in the field of view can be provided using the combined receive radar signal. One or more attributes of the one or more areas of interest can be rendered using the representation of the one or more areas of interest.

The system and method represents a high-resolution, three-dimensional, multi-static precipitation RADAR approach that employs agile microsatellites, in formation and remotely coupled, via a new high-precision, ultra-low power, remote timing synchronization technology. This system and method uses multi-static RADAR interferometric methods implemented via a microsatellite formation to synthesize an effectively large (e.g., 15 m) aperture to provide about 1 km horizontal resolution and about 125 m vertical resolution in the Ku-band.

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.