Surface determination systems, threat detection systems and medical treatment systems are described. According to one aspect, a surface determination system includes processing circuitry configured to access a three-dimensional complex-valued image volume of a target, define image locations of the image volume using first and second dimensions of the image volume, for each of the first locations, identify voxels along a third dimension of the image volume that correspond to the respective first location, for each of the first locations, select one voxel that corresponds to the first location as having an increased amplitude compared with other voxels that correspond to the first location, and for each selected voxel, use phase information to identify a second location in the third dimension for the selected voxel that corresponds to a location of a surface of the target and that is different than a third location of the respective voxel.

A method comprises at least: a first radar processing for locating and estimating the trajectory of a target on the basis of measurements of radial distances, of Doppler frequency and of angle of azimuth and of elevation of the target arising from a radar signal emitted towards the target; a second radar processing of location and of trajectory of the target along a vertical axis, by applying the principle of the inverse synthetic antenna; the disparity between the given trajectory and the trajectory estimated by the first processing, projected on a horizontal plane, and the disparity between the given trajectory and the trajectory estimated by the second processing according to the vertical axis being used to control the direction of displacement of the target.

An embodiment method includes: receiving radar data at a millimeter-wave radar sensor, the radar data being generated in response to an incident radio-frequency signal reflecting off an object located in a field of view of the millimeter-wave radar sensor; filtering the radar data to generate a first-filtered signal; determining a trajectory of motion corresponding to the first-filtered signal; and determining whether the trajectory of motion corresponds to a human signature, the human signature being associated with a respective operation of a vehicle.

A radar imaging system to reconstruct a radar reflectivity image of a scene including an object moving with the scene, includes an optical sensor to track the object over a period of time including multiple time steps to produce, for each of the multiple time steps, a deformation of a nominal shape of the object, and an electromagnetic sensor to acquire snapshots of the scene over the multiple time steps to produce a set of radar reflectivity image of the object with deformed shapes defined by the corresponding deformations of the nominal shape of the object. The system also includes a processor configured to determine, for each of the multiple time steps using the deformation determined for the corresponding time step, a transformation between the radar reflectivity image of the object acquired by the electromagnetic sensor at the corresponding time step and a radar reflectivity image of the object in the prototypical pose, and to combine the radar reflectivity images of the object with deformed shapes transformed with the corresponding transformations to produce the radar reflectivity image of the object in the prototypical pose.

Disclosed is a calibration method of performing dual radiometric compensation by using an antenna gain pattern of a synthetic aperture radar (SAR) both in a time domain and in a frequency domain. The method may include performing frequency-domain radiometric compensation in relation to an elevation angle and performing time-domain radiometric compensation in relation to a frequency to calibrate the antenna gain pattern.

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.

In accordance with an embodiment, a method of monitoring an air flow includes performing a plurality of radar measurements using a millimeter-wave radar sensor with a line of sight having a component perpendicular to a direction of an air flow, detecting an object in the air flow based on the plurality of radar measurements, calculating a displacement of the object and a size of the object based on the plurality of radar measurements, estimating a velocity of the object based on the calculated displacement, and calculating a risk metric based on the calculated size of the object and estimated velocity of the object.

A radar imaging device having a mission to produce a radar image of a given target, comprising a step of determining the trajectory of the carrier of the imaging device comprises at least: a phase of determining a segment of trajectory for the picture capture, as a function of the position of the target and of the type of image to be produced, the picture capture segment being dedicated to the picture capture of the target by the imaging device; a phase of adding a segment of trajectory of stabilizing the carrier, situated upstream in the extension of the picture capture segment; a phase of addition of a segment of trajectory for homing the carrier onto the stabilizing segment.

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 method includes transmitting, by a radiofrequency identification (RFID) reader device, a first electromagnetic radiation at a first polarization to a scan area and second electromagnetic radiation at a second polarization to the scan area. Re-radiated first electromagnetic radiation is received from an RFID tag located in the scan area at the first polarization. Re-radiated second electromagnetic radiation is received from the RFID tag at the second polarization. A radar image is generated based on the first and second re-radiated electromagnetic radiation. One or more items of information encoded in one or more microstructure elements located on the RFID tag are decoded based on the generated radar image. An RFID reader device and an RFID system are also disclosed.