Systems and methods according to one or more embodiments are provided for registration of synthetic aperture range profile data to aid in SAR-based navigation. In one example, a SAR-based navigation system includes a memory comprising a plurality of executable instructions. The SAR-based navigation system further includes a processor adapted to receive range profile data associated with observed views of a scene, compare the range profile data to a template range profile data of the scene, and estimate registration parameters associated with the range profile data relative to the template range profile data to determine a deviation from the template range profile data.

Method and device for radar transmission and reception by dynamic change of polarization notably for the implementation of interleaved radar modes are provided. A radar transmission-reception method and a device for implementing this method, the method alternatively implementing two modes of operation, a short range mode exploiting short pulses and a long range mode exploiting modulated long pulses, the method consisting, for each mode, in: producing two synchronous radiofrequency (RF) transmission signals having between them a phase-shift of controllable given value; radiating two radiofrequency waves, each corresponding to one of the transmission RF signals produced, by means of two colocated radiating sources each having a given polarization axis; handling the reception of the backscattered radiofrequency signals picked up by each of the radiating sources, and delivering two radiofrequency (RF) reception signals each corresponding to a radiofrequency signal picked up by one of the radiating sources, a phase-shift being applied between the two signals delivered, being able to be determined as being equal to .

SAR imaging may be performed with range-resolved reflection data, where a spread-spectrum signal, such as a code division multiple access (CDMA) signal, is transmitted instead of a simple frequency chirp. The reflected spread-spectrum signal may be analyzed to gather range-resolved reflection data. Range-resolved reflection data may be gathered at each angular view. This data may be used to construct a more accurate approximation of the Fourier transform of the desired image than can be done by a conventional SAR approach. The image may be reconstructed from this Fourier transform using Fourier inversion techniques similar to those used in conventional SAR approaches. The range-resolved reflection scheme generally requires somewhat more processing to recover the image as compared with conventional SAR systems, but provides a significantly more stable image with less degradation from effects that plague conventional SAR systems. This can eliminate the need for phase coherency altogether and also eliminate phase drift, which leads to image distortion. This may be especially well suited for high resolution imaging of relatively large targets.

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.

Images of a scene are acquired from a moving carrier that is equipped with a sensor. The angular direction of the line of sight of the sensor is automatically controlled. The acquisition is carried out: for a first position of the carrier, with automatic control allowing an outward scan, combined with a scan in step-and-stare mode with a biaxial stare micro-movement, of a band of terrain of the scene to be carried out, a first strip of images thus being acquired, at least one other strip of images of the same zone of terrain being acquired by reiterating these scanning steps for at least one other position of the carrier, and each image of another strip being acquired with a preset degree of overlap with the images of the first strip.

A Spotlight SAR imaging mode is implemented by a synthetic aperture radar (SAR) system in which an SAR controller intentionally spoils a transmit beam of the SAR antenna to form a spoiled transmit beam. The SAR system transmits pulses using the spoiled transmit beam, divides the SAR antenna into a plurality of azimuth apertures, receives received pulses by the SAR antenna using a number M of multiple receive beams, processes data received by each of the number M of multiple receive beams to generate a number M of sub-images by the SAR processor; and coherently combines two or more of the number M of sub-images to form a Spotlight image. Thus, a multi-aperture antenna comprises multiple azimuth apertures (i.e., a sub apertures), each formed from one or more azimuth phase centers. The sub-apertures can be independent from one another. The sub-apertures can keep a target illuminated by the beam for a longer time than conventional Stripmap mode, for example. The sub-apertures can be combined in processing to form a high resolution image, with high image quality.

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 signal processor 2 is configured so as to compensate for a peak shift of the distance between an SAR sensor 1 and a target, the peak shift occurring in the received signal subjected to range compression performed by an image reconstruction processing unit 14 due to a movement of the SAR sensor 1 during a time period until a reflected wave of a pulse signal is received by the SAR sensor 1 after the pulse signal is emitted from the SAR sensor 1. As a result, even when the SAR sensor 1 moves, an SAR image in which no azimuth ambiguity occurs can be reconstructed.

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.

Systems and methods according to one or more embodiments are provided for mapping and registration of synthetic aperture raw radar data to aid in SAR-based navigation. In one example, a SAR-based navigation system includes a memory including executable instructions and a processor adapted to receive phase history data associated with observation views of a scene. The processor further converts the received phase history data associated with the observation views to a range profile of the scene. The range profile is compared to a range profile template of the scene to estimate a geometric transformation of the scene encoded in the received phase history data with respect to a reference template.