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Vu, Viet Thuy
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Publications (10 of 80) Show all publications
Vu, V. T., Alves, D., Palm, B., Pettersson, M., Dammert, P. & Hellsten, H. (2019). A detector for wavelength resolution SAR incoherent change detection. In: 2019 IEEE Radar Conference, RadarConf 2019: . Paper presented at IEEE Radar Conference, RadarConf, Boston, 22 April through 26 April 2019. Institute of Electrical and Electronics Engineers Inc., Article ID 8835574.
Open this publication in new window or tab >>A detector for wavelength resolution SAR incoherent change detection
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2019 (English)In: 2019 IEEE Radar Conference, RadarConf 2019, Institute of Electrical and Electronics Engineers Inc. , 2019, article id 8835574Conference paper, Published paper (Refereed)
Abstract [en]

This paper introduces an effective detector for wavelength-resolution SAR incoherent change detection. The detector is derived from Bayes' theorem. The input of the detector is the differences between surveillance and reference magnitude images simply obtained by a subtraction while the output is a summary of the detected changes. The proposed detector is tested with 24 CARABAS images that were obtained from the measurement campaign in northern Sweden in 2002. The testing results show that the detector can provide a high average detection probability, e.g., about 96%, with a very low false alarm rate, e.g., only 0.35 per square kilometer. © 2019 IEEE.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2019
Keywords
Radar imaging, Bayes' theorem, CARABAS, Change detection, Detection probabilities, False alarm rate, Measurement campaign, Northern sweden, Wavelength resolution, Synthetic aperture radar
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:bth-18815 (URN)10.1109/RADAR.2019.8835574 (DOI)2-s2.0-85073100690 (Scopus ID)9781728116792 (ISBN)
Conference
IEEE Radar Conference, RadarConf, Boston, 22 April through 26 April 2019
Available from: 2019-10-31 Created: 2019-10-31 Last updated: 2019-10-31Bibliographically approved
Vu, V. T., Gomes, N. R., Pettersson, M., Dämmert, P. & Hellsten, H. (2019). Bivariate Gamma Distribution for Wavelength-Resolution SAR Change Detection. IEEE Transactions on Geoscience and Remote Sensing, 57(1), 473-481
Open this publication in new window or tab >>Bivariate Gamma Distribution for Wavelength-Resolution SAR Change Detection
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2019 (English)In: IEEE Transactions on Geoscience and Remote Sensing, ISSN 0196-2892, E-ISSN 1558-0644, Vol. 57, no 1, p. 473-481Article in journal (Refereed) Published
Abstract [en]

A gamma probability density function (pdf) is shown to be an alternative to model the distribution of the magnitudes of high-resolution, i.e., wavelength-resolution, synthetic aperture radar (SAR) images. As investigated in this paper, it is more appropriate and more realistic statistical in comparison with, e.g., Rayleigh. A bivariate gamma pdf is considered for developing a statistical hypothesis test for wavelength-resolution incoherent SAR change detection. The practical issues in implementation of statistical hypothesis test, such as assumptions on target magnitudes, estimations for scale and shape parameters, and implementation of modified Bessel function, are addressed. This paper also proposes a simple processing scheme for incoherent change detection to validate the proposed statistical hypothesis test. The proposal was experimented with 24 CARABAS data sets. With an average detection probability of 96%, the false alarm rate is only 0.47 per square kilometer. IEEE

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2019
Keywords
Bivariate gamma, CARABAS, change detection, synthetic aperture radar (SAR)., Probability density function, Probability distributions, Radar imaging, Statistical tests, Tracking radar, Bivariate, Bivariate gamma distribution, Probability density function (pdf), Scale and shape parameters, Statistical hypothesis test, Synthetic aperture radar (SAR) images, Synthetic aperture radar
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:bth-16936 (URN)10.1109/TGRS.2018.2856926 (DOI)000455089000036 ()2-s2.0-85051396922 (Scopus ID)
Available from: 2018-08-24 Created: 2018-08-24 Last updated: 2019-01-28Bibliographically approved
Gomes, N. R., Dammert, P., Pettersson, M., Vu, V. T. & Hellsten, H. (2019). Comparison of the Rayleigh and K-Distributions for Application in Incoherent Change Detection. IEEE Geoscience and Remote Sensing Letters, 16, 756-760
Open this publication in new window or tab >>Comparison of the Rayleigh and K-Distributions for Application in Incoherent Change Detection
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2019 (English)In: IEEE Geoscience and Remote Sensing Letters, ISSN 1545-598X, E-ISSN 1558-0571, Vol. 16, p. 756-760Article in journal (Refereed) Published
Abstract [en]

The aim of this letter is to compare two incoherent change-detection algorithms for target detection in low-frequency ultrawideband (UWB) synthetic aperture radar (SAR) images. The considered UWB SAR operates in the frequency range from 20 to 90 MHz. Both approaches employ a likelihood ratio test according to the Neyman–Pearson criterion. First, the bivariate Rayleigh probability distribution is used to implement the likelihood ratio test function. This distribution is well known and has been used for change-detection algorithms in low-frequency UWB SAR with good results. Aiming to minimize the false alarm rate and taking into consideration that low-frequency UWB SAR images have high resolution compared to the transmitted wavelength, the second approach implements the test by using a bivariate K-distribution. This distribution has scale and shape parameters that can be used to adjust it to the data. No filter is applied to the data set images, and the results show that with a good statistical model, it is not needed to rely on filtering the data to decrease the number of false alarms. Therefore, we can have a better tradeoff between resolution and detection performance.

Place, publisher, year, edition, pages
IEEE, 2019
Keywords
Change detection, likelihood ratio test, synthetic aperture radar (SAR).
National Category
Signal Processing
Identifiers
urn:nbn:se:bth-17863 (URN)10.1109/LGRS.2018.2881733 (DOI)000466228400019 ()
Available from: 2019-04-30 Created: 2019-04-30 Last updated: 2019-06-14Bibliographically approved
Ludwig Barbosa, V., Sievert, T., Rasch, J., Carlström, A., Pettersson, M. & Vu, V. T. (2019). Evaluation of Ionospheric Scintillation in GNSS Radio Occultation Measurements and Simulations. Radio Science
Open this publication in new window or tab >>Evaluation of Ionospheric Scintillation in GNSS Radio Occultation Measurements and Simulations
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2019 (English)In: Radio Science, ISSN 0048-6604, E-ISSN 1944-799XArticle in journal (Refereed) Submitted
Abstract [en]

Like any other system relying on trans-ionospheric propagation, GNSS Radio Occultation (GNSS-RO) is affected by ionospheric conditions during measurements. Regions of plasma irregularities in F-region create abrupt gradients in the distribution of ionized particles. Radio signals propagated through such regions suffer from constructive and destructive contributions in phase and amplitude, known as scintillations. Different approaches have been proposed in order to model and reproduce the wave propagation through ionospheric irregularities. We present simulations considering an one-component inverse power-law model of irregularities integrated with Multiple Phase Screen (MPS) propagation. In this work, the capability of the scintillation model to reproduce features in the signal amplitude of low latitude MetOp measurements in the early hours of DOY 76, 2015 (St. Patrick’s Day geomagnetic storm) is evaluated. Power spectral density (PSD) analysis, scintillation index, decorrelation time and standard deviation of neutral bending angle are considered in the comparison between the simulations and RO measurements. The results validate the capability of the simulator to replicate an equivalent total integrated phase variance in cases of moderate to strong scintillation.

National Category
Remote Sensing
Identifiers
urn:nbn:se:bth-18898 (URN)
Funder
Swedish National Space Board
Available from: 2019-11-11 Created: 2019-11-11 Last updated: 2019-11-18Bibliographically approved
Pettersson, M., Dahl, M., Vu, V. T. & Javadi, M. S. (2019). Future Satellite and Drone Monitoring of the Baltic‐Adriatic Corridor,Harbors, and Motorways of the Sea.
Open this publication in new window or tab >>Future Satellite and Drone Monitoring of the Baltic‐Adriatic Corridor,Harbors, and Motorways of the Sea
2019 (English)Report (Other academic)
Publisher
p. 50
National Category
Engineering and Technology
Identifiers
urn:nbn:se:bth-18575 (URN)
Projects
Tentacle
Available from: 2019-09-04 Created: 2019-09-04 Last updated: 2019-09-06Bibliographically approved
Ludwig Barbosa, V., Rasch, J., Carlström, A., Pettersson, M. & Vu, V. T. (2019). GNSS Radio Occultation Simulation Using MultiplePhase Screen Orbit Sampling. IEEE Geoscience and Remote Sensing Letters
Open this publication in new window or tab >>GNSS Radio Occultation Simulation Using MultiplePhase Screen Orbit Sampling
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2019 (English)In: IEEE Geoscience and Remote Sensing Letters, ISSN 1545-598X, E-ISSN 1558-0571Article in journal (Refereed) Epub ahead of print
Abstract [en]

Wave optics propagators (WOPs) are commonlyused to describe the propagation of radio signals through earth’satmosphere. In radio occultation (RO) context, multiple phasescreen (MPS) method has been used to model the effects of theatmosphere in Global Navigation Satellite System (GNSS) signalsduring an occultation event. WOP implementation includes,in addition to MPS, a diffraction integral as the final step tocalculate the radio signal measured in the low-earth orbit (LEO)satellite. This approach considers vacuum as the propagationmedium at high altitudes, which is not always the case when theionosphere is taken into account in simulations. An alternativeapproach is using MPS all the way to LEO in order to samplethe GNSS signal in orbit. This approach, named MPS orbitsampling (MPS-OS), is evaluated in this letter. Different scenariosof setting occultation assuming a short segment of the LEO orbithave been simulated using MPS and MPS-OS. Results have beencompared to Abel transform references. Furthermore, a longsegment scenario has been evaluated as well. A comparison ofbending angle (BA) and residual ionospheric error (RIE) showsthe equivalence between MPS and MPS-OS results. The mainapplication of MPS-OS should be in occultation events with longsegments of orbit and including ionosphere, in which a standardWOP may not be appropriate.

National Category
Remote Sensing
Identifiers
urn:nbn:se:bth-18897 (URN)10.1109/LGRS.2019.2944537 (DOI)
Projects
National Space Engineering Program (NRFP-3), grant 241/15, Swedish National Space Agency (Rymdstyrelsen)
Funder
Swedish National Space Board
Available from: 2019-11-11 Created: 2019-11-11 Last updated: 2019-11-18Bibliographically approved
Vu, V. T., Pettersson, M., Sjögren, T. & Gustavsson, A. (2018). A hybrid GMTI method for reliable detec ion results in SAR images. In: Bao, VNQ Duy, TT (Ed.), PROCEEDINGS OF 2018 2ND INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN SIGNAL PROCESSING, TELECOMMUNICATIONS & COMPUTING (SIGTELCOM 2018): . Paper presented at Conference: 2nd International Conference on Recent Advances in Signal Processing, Telecommunications and Computing (SigTelCom), Ho Chi Minh, JAN 29-31 (pp. 73-78). IEEE
Open this publication in new window or tab >>A hybrid GMTI method for reliable detec ion results in SAR images
2018 (English)In: PROCEEDINGS OF 2018 2ND INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN SIGNAL PROCESSING, TELECOMMUNICATIONS & COMPUTING (SIGTELCOM 2018) / [ed] Bao, VNQ Duy, TT, IEEE , 2018, p. 73-78Conference paper, Published paper (Refereed)
Abstract [en]

Stand-alone synthetic aperture radar (SAR) ground moving target indication (GNITI) 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 TanDEMX and TerraSAR-X operating in monostatic pursuit mode. The ground scene where the measurements were conducted is around Mantorp, west of Linkoping, Sweden.

Place, publisher, year, edition, pages
IEEE, 2018
National Category
Telecommunications Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:bth-17697 (URN)000458556800014 ()978-1-5386-2976-5 (ISBN)
Conference
Conference: 2nd International Conference on Recent Advances in Signal Processing, Telecommunications and Computing (SigTelCom), Ho Chi Minh, JAN 29-31
Available from: 2019-03-07 Created: 2019-03-07 Last updated: 2019-03-08Bibliographically approved
Vu, V. T., Pettersson, M., Sjögren, T. & Gustavsson, A. (2018). A hybrid GMTI method for reliable detection results in SAR images. In: Proceedings - 2018 2nd International Conference on Recent Advances in Signal Processing, Telecommunications and Computing, SIGTELCOM 2018: . Paper presented at 2nd International Conference on Recent Advances in Signal Processing, Telecommunications and Computing, SIGTELCOM, Ho Chi Minh City (pp. 73-78). Institute of Electrical and Electronics Engineers Inc.
Open this publication in new window or tab >>A hybrid GMTI method for reliable detection results in SAR images
2018 (English)In: Proceedings - 2018 2nd International Conference on Recent Advances in Signal Processing, Telecommunications and Computing, SIGTELCOM 2018, Institute of Electrical and Electronics Engineers Inc. , 2018, p. 73-78Conference paper, Published paper (Refereed)
Abstract [en]

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.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2018
Keywords
Radar signal processing, Space time adaptive processing, Synthetic aperture radar, Ground moving target indication, Ground moving targets, Hybrid method, Monostatic, Moving target detection, Reliable detection, Stand -alone, TerraSAR-X, Radar imaging
National Category
Signal Processing Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:bth-16538 (URN)10.1109/SIGTELCOM.2018.8325809 (DOI)2-s2.0-85047862168 (Scopus ID)9781538629765 (ISBN)
Conference
2nd International Conference on Recent Advances in Signal Processing, Telecommunications and Computing, SIGTELCOM, Ho Chi Minh City
Available from: 2018-06-18 Created: 2018-06-18 Last updated: 2018-06-18Bibliographically approved
Palm, B., Alves, D., Vu, V. T., Pettersson, M., Bayer, F., Cintra, R., . . . Hellsten, H. (2018). Autoregressive model for multi-pass SAR change detection based on image stacks. In: Bovolo F.,Bruzzone L. (Ed.), Proceedings of SPIE - The International Society for Optical Engineering: . Paper presented at Image and Signal Processing for Remote Sensing XXIV 2018, Berlin, 10 September 2018 through 12 September 2018. SPIE, 10789, Article ID 1078916.
Open this publication in new window or tab >>Autoregressive model for multi-pass SAR change detection based on image stacks
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2018 (English)In: Proceedings of SPIE - The International Society for Optical Engineering / [ed] Bovolo F.,Bruzzone L., SPIE , 2018, Vol. 10789, article id 1078916Conference paper, Published paper (Refereed)
Abstract [en]

Change detection is an important synthetic aperture radar (SAR) application, usually used to detect changes on the ground scene measurements in different moments in time. Traditionally, change detection algorithm (CDA) is mainly designed for two synthetic aperture radar (SAR) images retrieved at different instants. However, more images can be used to improve the algorithms performance, witch emerges as a research topic on SAR change detection. Image stack information can be treated as a data series over time and can be modeled by autoregressive (AR) models. Thus, we present some initial findings on SAR change detection based on image stack considering AR models. Applying AR model for each pixel position in the image stack, we obtained an estimated image of the ground scene which can be used as a reference image for CDA. The experimental results reveal that ground scene estimates by the AR models is accurate and can be used for change detection applications. © 2018 SPIE.

Place, publisher, year, edition, pages
SPIE, 2018
Series
Proceedings of SPIE, ISSN 0277-786X
Keywords
AR models, Change detection, SAR, Time series, Image enhancement, Radar measurement, Remote sensing, Synthetic aperture radar, Auto regressive models, Change detection algorithms, Pixel position, Reference image, Research topics, Synthetic aperture radar (SAR) images, Radar imaging
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:bth-17475 (URN)10.1117/12.2325661 (DOI)000455305000036 ()2-s2.0-85059005687 (Scopus ID)9781510621619 (ISBN)
Conference
Image and Signal Processing for Remote Sensing XXIV 2018, Berlin, 10 September 2018 through 12 September 2018
Available from: 2019-01-09 Created: 2019-01-09 Last updated: 2019-01-28Bibliographically approved
Sievert, T., Rasch, J., Carlström, A., Pettersson, M. & Vu, V. T. (2018). Comparing reflection signatures in radio occultation measurements using the full spectrum inversion and phase matching methods. In: Comeron A.,Kassianov E.,Picard R.H.,Schafer K.,Weber K. (Ed.), PROCEEDINGS VOLUME 10786; Remote Sensing of Clouds and the Atmosphere XXIII: . Paper presented at Remote Sensing of Clouds and the Atmosphere XXIII 2018; Berlin; Germany; 12 September 2018 through 13 September 2018. SPIE - International Society for Optical Engineering, Article ID 107860A.
Open this publication in new window or tab >>Comparing reflection signatures in radio occultation measurements using the full spectrum inversion and phase matching methods
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2018 (English)In: PROCEEDINGS VOLUME 10786; Remote Sensing of Clouds and the Atmosphere XXIII / [ed] Comeron A.,Kassianov E.,Picard R.H.,Schafer K.,Weber K., SPIE - International Society for Optical Engineering, 2018, article id 107860AConference paper, Published paper (Refereed)
Abstract [en]

Global Navigation Satellite System Radio Occultation (GNSS-RO) is an important technique used to sound the Earth's atmosphere and provide data products to numerical weather prediction (NWP) systems as well as toclimate research. It provides a high vertical resolution and SI-traceability that are both valuable complements toother Earth observation systems. In addition to direct components refracted in the atmosphere, many received RO signals contain reflected components thanks to the specular and relatively smooth characteristics of the ocean. These reflected components can interfere the retrieval of the direct part of the signal, and can also contain meteorological information of their own, e.g., information about the refractivity at the Earth's surface. While the conventional method to detect such reflections is by using radio-holographic methods, it has been shown that it is possible to see reflections using wave optics inversion, specically while inspecting the amplitude of the output of phase matching (PM). The primary objective of this paper is to analyze the appearance of these reflections in the amplitude output from another wave optics algorithm, namely the much faster full spectrum inversion (FSI). PM and FSI are closely related algorithms - they both use the method of stationary phase to derive the bending angle from a measured signal. We apply our own implementation of FSI to the same GNSS-RO measurements that PM was previously applied to and show that the amplitudes of the outputs again indicate reflection in the surface of the ocean. Our results show that the amplitudes output from the FSI and PM algorithms are practically identical and that the reflection signatures thus appear equally well.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2018
Keywords
radio occultation, wave optics, re ections, full spectrum inversion
National Category
Meteorology and Atmospheric Sciences Signal Processing
Identifiers
urn:nbn:se:bth-17132 (URN)10.1117/12.2325386 (DOI)000453909700007 ()9781510621558 (ISBN)
Conference
Remote Sensing of Clouds and the Atmosphere XXIII 2018; Berlin; Germany; 12 September 2018 through 13 September 2018
Available from: 2018-10-16 Created: 2018-10-16 Last updated: 2019-01-10Bibliographically approved
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