A Large Along-Track Baseline Approach for Ground Moving Target Indication Using TanDEM-X

In the paper a new method for ground moving target indication (GMTI) using two satellites (i.e. the TerraSAR-X and the TanDEM-X satellite) together is presented. The along-track baseline between the satellites is chosen to be in the order of several kilometres, so that each satellite observes the same moving vehicles at different times in the order of one to several seconds. The proposed method allows the estimation of the ground velocity of the moving targets as well as the estimation of the broadside positions without the need of complex bistatic processing techniques

Detection of moving targets in SAR

Основная статьяRadar with ground moving target indication (GMTI) is intended to isolate the signals of moving targets from the whole mass of signals reflected by different objects. In this work, we investigate two approaches to form GMIT images: displaced phase center antenna algorithm (DPCA) and along-track interferometry algorithm (ATI) by using the mathematical model of SAR

Facing channel calibration issues affecting passive radar DPCA and STAP for GMTI

This paper addresses the problem of clutter cancellation for ground moving target indication (GMTI) in multi-channel passive radar on mobile platforms. Specifically, the advantages of a space-time adaptive processing (STAP) approach are presented, compared to a displaced phase centre antenna (DPCA) approach, in the case of an angle-dependent imbalance affecting the receiving channels. The schemes are tested against simulated clutter data. Finally, a space-time GLRT detection scheme is proposed, where steering vector is not specified in the spatial domain, resulting in a non-coherent integration of target echoes across the receiving channels. Such solution offers comparable clutter cancellation capability and is more robust against significant calibration errors compared to a conventional GLRT detector, which suffers from spatial steering vector mismatches

Raw Data Based Two-Aperture SAR Ground Moving Target Indication

Abstract-This paper investigates the capability of classical two-channel SAR ground moving target indication (GMTI) techniques, such as Displaced Phase Center Antenna (DPCA) or Along-Track Interferometry (ATI) when implemented on azimuth-uncompressed SAR data, rather than the processed SAR image. By transforming the data into the Doppler frequency domain a complete target detection and parameter estimation scheme is proposed. In contrast to the conventional image based algorithms, the proposed techniques are able to detect even fast movers. The GMTI feasibility is demonstrated with measured airborne data

Digital Beamforming and Traffic Monitoring Using the new FSAR System of DLR

In November 2006 the first X-band test flight of DLR’s new FSAR system has been performed successfully and in February 2007 the first flight campaign has been conducted for acquiring experimental multi-channel data of controlled ground moving targets. In the paper the performed experiments and the used setup of the FSAR X-band section are described and preliminary results in the field of ground moving target indication and digital beamforming are presented

Detección y estimación de velocidad de blancos móviles utilizando técnicas GMTI en imágenes SAR

Tesis (Magister en Aplicaciones de Información Espacial)--Universidad Nacional de Córdoba, Facultad de Matemática, Astronomía, Física y Computación, 2019.Maestría conjunta con el Instituto de Altos Estudios Espaciales "Mario Gulich"-CONAEEl foco de este trabajo está puesto en el estudio y desarrollo de técnicas Ground Moving Target Indication (GMTI) aplicadas en imágenes SAR (Synthetic Aperture Radar), destinadas a detectar y estimar parámetros de velocidad de objetos en movimiento, como por ejemplo autos o camiones. Se propone un esquema de procesamiento de bajo costo computacional basada simplemente en transformadas de Fourier y multiplicaciones de exponenciales complejas. La validez y eficiencia del esquema propuesto es estudiado procesando imágenes COSMO-SkyMed (CSK) Single Look Complex (SLC) adquiridas en modo Spotlight sobre países distintos. Los resultados obtenidos verifican la teoría estudiada con su aplicación en datos reales, demostrando de este modo la factibilidad de implementación de técnicas GMTI sobre datos SAR.The focus of this work is on the study and development of Ground Moving Target Indication (GMTI) techniques applied in Synthetic Aperture Radar (SAR) images, aimed at detecting and estimating velocity parameters of moving targets, such as cars or trucks. A low-cost computational processing scheme is proposed based on Fourier transforms and multiplications of complex exponentials. The validity and efficiency of the proposed scheme is studied by processing COSMO-SkyMed (CSK) Single Look Complex (SLC) images acquired in Spotlight mode over different countries. The results obtained verify the theory studied with its application in real data, thus demonstrating the feasibility of implementing GMTI techniques on SAR data.Fil: Testa, Alejandro Iván. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina.Fil: Testa, Alejandro Iván. Universidad Nacional de Córdoba. Instituto de Altos Estudios Espaciales Mario Gulich; Argentina.Fil: Testa, Alejandro Iván. Comisión Nacional de Actividades Espaciales. Instituto de Altos Estudios Espaciales Mario Gulich; Argentina

Mitigating Interference with Knowledge-Aided Subarray Pattern Synthesis and Space Time Adaptive Processing

Phased arrays are essential to airborne ground moving target indication (GMTI), as they measure the spatial angle-of-arrival of the target, clutter, and interference signals. The spatial and Doppler (temporal) frequency is utilized by space-time adaptive processing (STAP) to separate and filter out the interference from the moving target returns. Achieving acceptable airborne GMTI performance often requires fairly large arrays, but the size, weight and power (SWAP) requirements, cost and complexity considerations often result in the use of subarrays. This yields an acceptable balance between cost and performance while lowering the system’s robustness to interference. This thesis proposes the use of knowledge aided adaptive radar to institute adaptive subarray nulling in concert with digital space-time adaptive processing to improve performance in the presence of substantial interference. This research expands previous work which analyzed a clutter-free airborne moving-target indication (AMTI) application of knowledge-aided subarray pattern synthesis (KASPS) [1] and updates this previous research by applying the same concept to the GMTI application with clutter and STAP

TechSat 21 and Revolutionizing Space Missions using Microsatellites

The Air Force Research Laboratory (AFRL) TechSat 21 flight experiment demonstrates a formation of three microsatellites flying in formation to operate as a “virtual satellite.” X-band transmit and receive payloads on each of the satellites form a large sparse aperture system. The satellite formation can be configured to optimize such varied missions as radio frequency (RF) sparse aperture imaging, precision geolocation, ground moving target indication (GMTI), single-pass digital terrain elevation data (DTED), electronic protection, single-pass interferometric synthetic aperture radar (IF-SAR), and high data-rate, secure communications. Benefits of such a microsatellite formation over single large satellites include unlimited aperture size and geometry, greater launch flexibility, higher system reliability, easier system upgrade, and low cost mass production. Key research has focused on the areas of formation flying and sparse aperture signal processing and been sponsored and guided by the Air Force Office of Scientific Research (AFOSR). The TechSat 21 Program Preliminary Design Review (PDR) was held in April 2001 and incorporated the results of extensive system trades to achieve a light-weight, high performance satellite design. An overview of experiment objectives, research advances, and satellite design is presented

Nearly orthogonal, doppler tolerant waveforms and signal processing for multi-mode radar applications

In this research, we investigate the design and analysis of nearly orthogonal, Doppler tolerant waveforms for diversity waveform radar applications. We then present a signal processing framework for joint synthetic aperture radar (SAR) and ground moving target indication (GMTI) processing that is built upon our proposed waveforms. ^ To design nearly orthogonal and Doppler tolerant waveforms, we applied direct sequence spread spectrum (DSSS) coding techniques to linear frequency modulated (LFM) signals. The resulting transmitted waveforms are rendered orthogonal using a unique spread spectrum code. At the receiver, the echo signal can be decoded using its spreading code. In this manner, transmit orthogonal waveforms can be matched filtered only with the intended receive signals. ^ Our proposed waveforms enable efficient SAR and GMTI processing concurrently without reconfiguring a radar system. Usually, SAR processing requires transmit waveforms with a low pulse repetition frequency (PRF) rate to reduce range ambigu- ity; on the other hand, GMTI processing requires a high PRF rate to avoid Doppler aliasing and ambiguity. These competing requirements can be tackled by employing some waveforms (with low PRF) for the SAR mission and other waveforms (with high PRF) for the GMTI mission. Since the proposed waveforms allow separation of individual waveforms at the receiver, we can accomplish both SAR and GMTI processing jointl

Multi-Channel Calibration for Airborne PostDoppler Space-Time Adaptive Processing

This paper presents a fast and efficient multichannel calibration algorithm for along-track systems, which in particular is evaluated for the post-Doppler space-time adaptive processing (PD STAP) technique. The calibration algorithm corrects the phase and magnitude offsets among the receiving channels, estimates and compensates the Doppler centroid variation caused by atmospheric turbulences by using the attitude angles of the antenna array. Important parameters and offsets are estimated directly from the radar rangecompressed data. The proposed algorithm is compared with the state-of-the-art Digital Channel Balancing technique based on real multi-channel X-band data acquired by the DLR’s airborne system F-SAR. The experimental results are shown and discussed in the frame of traffic monitoring applications