A navigation apparatus includes an image capturing device, template database, correlation device, evaluation device, and output interface. The image capturing device can create a radar image of a surround, the template database configured to provide at least one template substantially matched to the radar image and containing at least one geo-referenced landmark, the at least one geo-referenced landmark being geo-referenced by at least one geo-coordinate. The correlation device can correlate the at least one geo-referenced landmark in the at least one template with the radar image and provide the at least one geo-coordinate belonging to the at least one geo-referenced landmark. The evaluation device can determine a position of the navigation apparatus from the at least one geo-coordinate of the at least one geo-referenced landmark and from a setting of the image capturing device. The output interface is configured to provide the determined position.

A method of calculating power level reflectance σ.sub.0 of an object on the ground using synthetic aperture radar (SAR) image includes receiving the SAR image composed of pixels each having a complex value (I.sub.DN+jQ.sub.DN), local incidence angle data including local incidence angle values respectively corresponding to the pixels of the SAR image and a reflection coefficient K.sub.2 of the SAR image, calculating power level reflectance β.sub.0 on a slant range domain of a first object corresponding to a first pixel based on the complex value (I.sub.DN+jQ.sub.DN) of the first pixel in the SAR image and the reflection coefficient K.sub.2, and calculating, using an equation that σ.sub.0=β.sub.0.Math.(sin θ.sub.i).sup.2, power level reflectance σ.sub.0 of the first object on the ground based on the power level reflectance β.sub.0 of the first object on the slant range domain and the local incidence angle value θ.sub.i corresponding to the first pixel.

Disclosed is a synthetic aperture radar (SAR) system for target recognition with complex range profile. The SAR system comprising a memory, a recurrent neural network (RNN), a multi-layer linear network in signal communication the RNN, and a machine-readable medium on the memory. The machine-readable medium is configured to store instructions that, when executed by the RNN, cause the SAR system to perform various operations. The various operation comprise: receiving raw SAR data associated with observed views of a scene, wherein the raw SAR data comprises information captured via the SAR system; radio frequency (RF) preprocessing the received raw SAR data to produce a processed raw SAR data; converting the processed raw SAR data to a complex SAR range profile data; processing the complex SAR range profile data with the RNN having RNN states; and mapping the RNN states to a target class with the multi-layer linear network.

A SAR imaging method for interferometric analyses is provided, including: receiving raw SAR data related to two or more SAR acquisitions of one and the same area of the earth's surface carried out by one or more synthetic aperture radars; and processing the raw SAR data to generate SAR images. For each SAR acquisition, the respective raw SAR data is processed based on two different sets of processing parameters: a first set that is the same for all the SAR acquisitions and which comprises focusing Doppler parameters computed based on physical Doppler parameters related to all the SAR acquisitions; and a second set which comprises respective radiometric equalization Doppler parameters related to the SAR acquisition and computed based on respective physical Doppler parameters related to the SAR acquisition. Processing includes: focusing the raw SAR data related to all SAR acquisitions based on the focusing Doppler parameters and, for each SAR acquisition, applying a respective radiometric equalization, based on the respective radiometric equalization Doppler parameters, to the respective SAR data to compensate for possible differences in pointing of the synthetic aperture radar(s), without degrading azimuth resolution and without introducing radiometric distortions.

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.

The present invention concerns a method for performing SAR acquisitions, which comprises performing, in a time division fashion, SAR acquisitions of areas of a swath of earth's surface by means of a SAR system carried by an air or space platform; wherein performing SAR acquisitions in a time division fashion includes contemporaneously acquiring, in each pulse repetition interval, a plurality of areas of the swath that are separated in azimuth; and wherein the areas acquired in T successive pulse repetition intervals form an azimuth-continuous portion of said swath, T being an integer greater than one.

Described is a stripmap SAR system on a vehicle comprising an antenna that is fixed and directed outward from the side of the vehicle, a SAR sensor, a storage, and a computing device. The computing device comprises a memory, one or more processing units, and a machine-readable medium on the memory. The machine-readable medium stores instructions that, when executed by the one or more processing units, cause the stripmap SAR system to perform various operations. The operations comprise: receiving stripmap range profile data associated with observed views of a scene; transforming the received stripmap range profile data into partial circular range profile data; comparing the partial circular range profile data to a template range profile data of the scene; and estimating registration parameters associated with the partial circular range profile data relative to the template range profile data to determine a deviation from the template range profile data.

A computer-implemented method executed by one or more satellites for assessing crop development by using synthetic aperture radar (SAR) is presented. The method includes generating SAR images from scanning fields including crops, monitoring grown of the crops within the fields during a predetermined time period, and estimating a height of the crops during the predetermined time period by using interferometric information from one or more of the SAR images and tracking change in height and growth rates. The method further includes differentiating between crops in different fields by monitoring changes in the height of the crops during an entire growing season.

A method according to the present invention comprises the steps of: dividing SAR raw data into one or more sub-aperture data by a predetermined number in an azimuth direction; performing a spectral length extension FFT on the sub-aperture data in the azimuth direction; multiplying the sub-aperture data by a chirp scaling function; performing a range FFT on the sub-aperture data; performing range compression, SRC, and a bulk RCMC on the sub-aperture data; performing an inverse chirp-z transform on the sub-aperture data in a range direction; multiplying the divided sub-aperture data by a predetermined first function; performing an IFFT on the sub-aperture data in the azimuth direction; recombining the sub-aperture data; multiplying the recombined data by a second function and deramping same; performing an azimuth FFT on the recombined data; performing an azimuth IFFT on the recombined data; multiplying the recombined data by a third function and deramping same; performing the azimuth FFT on the recombined data; performing azimuth compression by multiplying the recombined data by a fourth function; performing an azimuth inverse chirp-z transform on the recombined data; and multiplying the recombined data by a fifth function for phase preservation.

A method for synthetic aperture radar signal processing includes storing signal responses of a radar signal in a memory buffer, wherein the stored signal responses are represented by a two-dimensional signal in an azimuth dimension and a range dimension. The method further includes frequency filtering the two-dimensional signal in the azimuth dimension. In addition, the method includes applying a Fourier transformation to the frequency filtered signal in the range dimension. The method further includes generating a synthetic aperture radar image based on the Fourier transformed frequency filtered signal.