| 1. |
- Alves, Dimas, I, et al.
(författare)
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Incoherent Change Detection Methods for Wavelength-Resolution SAR Image Stacks Based on Masking Techniques
- 2020
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Ingår i: 2020 IEEE National Radar Conference - Proceedings. - : IEEE. - 9781728189420
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Konferensbidrag (refereegranskat)abstract
- This paper presents two incoherent change detection methods for wavelength-resolution synthetic aperture radars (SAR) image stacks based on masking techniques. The first technique proposed is the Simple Masking Detection (SMD). This method uses the statistical behavior of pixels-sets in the image stack to create a binary mask, which is used to remove pixels that are not related to changes in a surveillance image from the same interest region. The second technique is the Multiple Concatenated Masking Detection (MCMD), which produces a more selective mask than the SMD by concatenating multiple masks from different image stacks. The MCMD can be used in specific applications where multiple stacks share common patterns of target deployments. Both proposed techniques were evaluated using 24 incoherent SAR images obtained by the CARABAS II system. The experimental results revealed that the proposed detection methods have better performance in terms of probability of detection and false alarm rate when compared with other change detection techniques, especially for high detection probabilities scenarios.
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| 2. |
- Alves, Dimas I, et al.
(författare)
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Statistical Analysis for Wavelength-Resolution SARImage Stacks : New Case Studies
- 2020
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Ingår i: XXXVIII SIMPÓSIO BRASILEIRO DE TELECOMUNICAÇÕES E PROCESSAMENTO DE SINAIS.
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Konferensbidrag (refereegranskat)abstract
- This paper presents new case studies for thestatistical analysis for wavelength resolution SAR image stacks.The statistical analysis considers the Anderson-Darling goodnessof-fit test in a set of pixel samples from the same position obtainedfrom a SAR image stack. The test is applied in wavelengthresolution SAR image stacks. The present work consists of twocase studies based on the use of multiple-pass stacks and TypeI error using the False Discovery Rate controlling procedures.In addition, an application scenario is presented for the studiedscenarios.
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| 3. |
- Batra, Aman, et al.
(författare)
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Experimental analysis of high resolution indoor THz SAR imaging
- 2020
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Ingår i: WSA 2020 - 24th International ITG Workshop on Smart Antennas. - : VDE Verlag GmbH. - 9783800752003
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Konferensbidrag (refereegranskat)abstract
- Synthetic Aperture Radar (SAR) technology is most commonly used in the frequency span of sub-30 GHz which provides the spatial resolution in the range of sub-cm. This technology is being extended to higher frequencies such as millimeter wave and THz region to achieve higher resolution in the range of sub-mm. This expands the SAR applications for material characterization, classification and sub-mm localization. However, the region is suitable for short propagation distance such as an indoor environment. Therefore, to investigate the achieved resolution and quality of the SAR images at THz, an indoor SAR testbed based on vector network analyzer has been setup for the measurements. This paper explains the indoor SAR geometry and describes the associated testbed along with the system parameters. The measurements are performed at a centre frequency of 275 GHz with a bandwidth of 110 GHz. The measurement results are analyzed for the theoretical resolution with the Backprojection Algorithm and the findings are presented in this paper. The sub-mm spatial resolution imaging of two small size metallic objects are performed. © WSA 2020.
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| 4. |
- Batra, Aman, et al.
(författare)
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Sub-mm Resolution Indoor THz Range and SAR Imaging of Concealed Object
- 2020
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Ingår i: 2020 IEEE MTT-S International Conference on Microwaves for Intelligent Mobility, ICMIM 2020. - : Institute of Electrical and Electronics Engineers Inc.. - 9781728167558
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Konferensbidrag (refereegranskat)abstract
- In radar systems, the frequency range is being extended to high frequencies such as THz for sub-mm resolution. The spectrum offers high resolution but on the contrary, propagation distance and penetration depth are limited because of smaller wavelength. It suffers from higher atmospheric absorption in comparison to sub-GHz systems. In comparison to optical technology, the radar technique majorly benefits with respect to the penetration property such as cloud/smoke cover penetration and detection of concealed objects. However, the THz range and synthetic aperture radar (SAR) imaging of concealed objects are not very well established. Therefore, this paper examines this property at THz. A testbed has been set up with a bandwidth of 110 GHz at a carrier frequency of 275 GHz. The imaging is performed of a very small metal object. Firstly, the sub-mm resolution is validated with the experiment after that the range and SAR imaging are performed in which this object is covered with different types of materials. The backscattered data is processed with the image reconstruction algorithms and the results are presented in this paper with respect to sub-mm resolution and detection. © 2020 IEEE.
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| 5. |
- Campos, Alexandre Becker, 1997-, et al.
(författare)
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UNSUPERVISED AUTOMATIC TARGET DETECTION FOR MULTITEMPORAL SAR IMAGES BASED ON ADAPTIVE K-MEANS ALGORITHM
- 2020
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Konferensbidrag (refereegranskat)abstract
- In this paper, we present an unsupervised automatic target detection algorithm for multitemporal SAR images. The proposed two-fold method is expected to reduce processing time for large scene sizes with sparse targets while still improving detection performance. Firstly, pixel blocks are extracted from an initial change map to reduce the algorithm's search space and favor target detection. Secondly, an adaptive k-means algorithm selects the number of clusters that better separates targets from false alarms, which are discarded. Preliminary results show the advantages of the proposed method in processing time and detection performance over a recently proposed supervised method for the CARABAS-II dataset.
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| 6. |
- Pernstal, Thomas, et al.
(författare)
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GIP test for Automotive FMCW interference Detection and Suppression
- 2020
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Ingår i: 2020 IEEE RADAR CONFERENCE (RADARCONF20). - : IEEE. - 9781728189420
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Konferensbidrag (refereegranskat)abstract
- This paper addresses the problem of mutual interference between automotive radars. The rapid growth of automotive and commercial radar systems on the market does not only facilitate new applications, e.g., advanced driver assistant systems, but also put demands on the possibilities for co-existence, i.e. cohabitant systems. For military radar systems, various jammer and interference mitigation methods have been extensively analyzed and evaluated for decades. However, until now, the co-existence and influence of jamming/interference have almost been ignored for the commercial radar business. A Generalized Inner Product, GIP, test based outlier detector and interference estimation is presented here, which suppress the interferences only in those Directions of Arrival, DOA, and time domain portions where the nuisance signals appear. We will denote this GIP test based Interference Detector and Suppression as the GIDS method. Using GIDS, the target detection performance for the specific interference DOA will merely have a small loss instead of being completely suppressed, e.g., sample matrix inversion implementation of spatial nulling. The proposed technique is robust and does not rely on any calibration for the interference cancellation. Based on simulation and experimental data, we have shown that without losing target detection performance, we achieved up to about 30 dB enhancement for the Signal to Interference and Noise Ratio.
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| 7. |
- Ramos, Lucas P., et al.
(författare)
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Change detection in UWB VHF SAR images exploiting flight heading diversity through robust principal component analysis
- 2020
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 9781510638792
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Konferensbidrag (refereegranskat)abstract
- Change detection methods are frequently associated with wavelength-resolution synthetic aperture radar (SAR) images for foliage-penetrating (FOPEN) applications (e.g., the detection of concealed targets in forestry areas), being a research topic of interest over the last decades. The challenge associated with the design of automated change detection techniques goes beyond performing the target detection. It is also related to clutter suppression aiming at a low false alarm rate (FAR). The problem of detecting targets and removing content in SAR data can be treated as an unsupervised signal separation problem, usually referred to as blind source separation (BSS). Additionally, low frequency wavelength-resolution SAR images can be considered to follow an additive separation model due to their backscatter characteristics. In this context, it is possible to explore robust principal component analysis (RPCA) as a source-separation method for problems in which the mixing model is additive and two-dimensional, as the interest SAR images. This paper presents a change detection method for wavelengthresolution SAR images based on the RPCA via principal component pursuit (PCP), considering the use of small image stacks to explore the data diversity from measurements of different flight headings. The proposed method is evaluated using real data obtained from measurements of the ultrawideband (UWB) very high frequency (VHF) SAR system CARABAS II. The experimental results show that the proposed method can achieve a high probability of detection (PD) values for a low FAR (i.e., PD of 0.98 for a FAR of 0.41 objects per square kilometer). Finally, discussions regarding the use of the RPCA in change detection methods and the diversity gains are provided in the paper. © SPIE. Downloading of the abstract is permitted for personal use only.
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| 8. |
- Vu, Viet Thuy, 1977-, et al.
(författare)
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CHANGE DETECTION AND SIGNATURE CLASSIFICATION FOR SAR GMTI
- 2020
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Ingår i: IGARSS 2020 - 2020 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM. - 9781728163741 ; , s. 1997-2000
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Konferensbidrag (refereegranskat)abstract
- The pursuit monostatic is a SAR operating mode that requires two SAR data acquisitions separated in short time (seconds) using the same flight tracks and being. In this case, the changes in a SAR scene come mainly from ground moving targets, thus opening up opportunities to detect ground moving targets using SAR change detection methods. The paper introduces a SAR GMTI method that is based on a change detection method in combination with a signature classification. The SAR GMTI method is tested with the pursuit monostatic data acquired by TerraSAR-X and TanDEM-X in 2015.
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| 9. |
- Vu, Viet Thuy, 1977-, et al.
(författare)
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ENHANCING CONVENTIONAL SAR CHANGE DETECTION PERFORMANCE WITH APODIZATION
- 2020
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Ingår i: IGARSS 2020 - 2020 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM. - 9781728163741 ; , s. 1985-1988
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Konferensbidrag (refereegranskat)abstract
- Conventional SAR refers to systems with small fractional bandwidth and short relative aperture whereas non-conventional SAR refers to systems with large fractional bandwidth and long relative aperture. The change detection methods developed for non-conventional SAR have been shown to be applicable to conventional SAR systems. However, the differences in characteristics of non-conventional and conventional SAR, especially spatial resolutions, degrade the change detection performance and cause some difficulties in evaluating change detection results when applying these methods to conventional SAR. SAR apodization, the effects of SAR apodization on change detection performance and change detection evaluation are investigated in this study.
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