Stand-alone synthetic aperture radar (SAR) ground moving target indication (GMTI) methods have both advantages and disadvantages. This paper introduces a hybrid SAR GMTI method that is based on two well-known methods: space time adaptive processing (STAP) and moving target detection by focusing (MTDF). The input of the proposed hybrid method is two time separated complex radar images. The output is detected ground moving targets, the target normalized relative speeds (NRS), and focused images of the detected targets. In the paper, we provide the mathematical background behind the hybrid SAR GMTI method in details. We also provide some experimental results for validating the proposed method. The data for the experiments was acquired in early 2015 by TanDEM-X and TerraSAR-X operating in monostatic pursuit mode. The ground scene where the measurements were conducted is around Mantorp, west of Linköping, Sweden. © 2018 IEEE.

This paper reports the measurement campaign Blekingetraffic that was performed by Blekinge Institute of Technology with collaboration with the partners. The measurements are part of a case study to evaluate the feasibility of spaceborne SAR for measuring traffic flow change before and after toll charge introduced in Sweden. The radar measurements were conducted around Pukavik, western of Karlshamn, Sweden in the end of 2015 and in the beginning of 2016. In this paper, the results of one of the controlled measurements performed in the first week of February 2016 is presented. In the ground scene, some trucks tracked with GPS were deployed in European route E22 and local roads. The trucks have either cabinets or food tankers resulting in different radar cross sections. The data acquisition is with TanDEM-X using two satellites giving up to 6 data channels. Since the measurements were performed at 5:00 pm there were unknown traffic i.e. trucks and cars that were not controlled. Therefore, the traffic on the roads was recorded by cameras next to the road and on a drone. The initial analysis of the measured data shows the possibilities to apply available processing techniques such as ground moving target indication and change detection to obtain the knowledge of traffic flow change. © 2017 IEEE.

SAR systems synthesizing circular apertures have been shown to result in better spatial resolutions than the ones synthesizing linear apertures. The paper presents an investigation about the enhancement of SAR spatial resolutions with the use of circular aperture. A comparison between the spatial resolutions obtained with a SAR system synthesizing a circular aperture and with the same SAR system synthesizing a linear aperture is therefore carried out. The studying results are verified by the experimental SAR data set provided by the experimental ground-based SAR system of Blekinge Institute of Technology (BTH GB-SAR).

In this paper, results of moving target detection in multichannel UHF-band Synthetic Aperture Radar (SAR) data are shown. The clutter suppression is done using Finite Impulse Response (FIR) filtering of multichannel SAR in combination with a 2-stage Fast Backprojection (FBP) algorithm to focus the moving target using relative speed. The FIR filter coefficients are chosen with the use of STAP filtering. Two parameters are used for target focusing, target speed in range and in azimuth. When the target is focused, both speed parameters of the target are found. In the experimental results, two channels were used in order to suppress clutter. In the resulting SAR images it is obvious that very strong scatterers and the forest areas have been suppressed in comparison to the moving target in the image scene. The gain obtained can be measured using SCNR gain, which is about 19dB. Another way to measure signal processing gain is the ability to suppress the strongest reflecting object in the SAR scene. The gain of target in relation to this object is 25dB. This shows that using UHF-band SAR GMTI for suppressing forest and increasing the target signal can work.

A 2-D spectrum for bistatic synthetic aperture radar is derived in this letter. The derivation is based on the commonly used mathematic principles such as themethod of stationary phase and the Fourier transform and the Lagrange inversion theorem in order to find the point of stationary phase in the method of stationary phase. Using the Lagrange inversion theorem allows minimizing the initial assumptions or the initial approximations. The derived 2-D spectrum is compared with the commonly used 2-D spectrum to verify it and illustrate its accuracy.

One important application of Synthetic Aperture Radars (SAR) is positioning of targets with high accuracy in both azimuth and range. If the target is moving and a multi-channel SAR system is used also the speed components in azimuth and range can be found with a high accuracy. In this paper we propose a method to estimate the accuracy of such a multichannel SAR system. The method is based on the Cramér-Rao Lower Bound (CRLB). To exemplify the method the variance of parameter estimates by a single channel UHF UWB SAR system is found.

The paper introduces a simple experimental groundbased SAR system for studying SAR fundamentals. The SAR system is developed on a vector network analyzer (VNA), for example Agilent E5071C, with some useful built-in functions such as transform and gating. The procedure of acquiring the data by using the SAR system is presented in details. The acquired empirical data is also used to reconstruct the illuminated scene. The possibilities to use the SAR system to support SAR research topics are also discussed in this paper.

The paper presents another possibility to focus moving targets using normalized relative speed (NRS). Similar to the currently used focusing approach, the focusing approach proposed in this paper aims at the ultrawideband and ultrawidebeam synthetic aperture radar systems (UWB SAR) like CARABAS-II. The proposal is shown to overcome the shortcomings of the original focusing approach and can be extended to more complicated cases, for example bistatic SAR.

Two fast time-domain algorithms are introduced for ultrawideband-ultrawidebeam (UWB) bistatic synthetic aperture radar (SAR) processing; they are bistatic fast backprojection (BiFBP) and bistatic fast factorized backprojection (BiFFBP). Both algorithms process radar echoes on a subaperture and subimage basis in order to minimize processing time. They are shown to work with any configuration of bistatic SAR. They also own time-domain characteristics, which are essential for UWB radar signal processing. BiFBP and BiFFBP are experimented successfully on the CARABAS-II simulated data.