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SAR speckle removal using hybrid frequency modulations / Shuaiqi Liu in IEEE Transactions on geoscience and remote sensing, vol 59 n° 5 (May 2021)
Titre : SAR speckle removal using hybrid frequency modulations Type de document : Article/Communication Auteurs : Shuaiqi Liu, Auteur ; Lele Gao, Auteur ; Yu Lei, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : pp 3956 - 3966 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications
[Termes IGN] artefact
[Termes IGN] classification par réseau neuronal convolutif
[Termes IGN] filtrage du bruit
[Termes IGN] filtre de déchatoiement
[Termes IGN] image radar moirée
[Termes IGN] modulation de fréquenceRésumé : (auteur) Synthetic aperture radar (SAR) images often interfere with speckle artifacts that have a great impact on subsequent processing and analysis operations. To remove speckle artifacts, this article introduces a hybrid denoising approach by using a convolutional neural network (CNN) and consistent cycle spinning (CCS) in the nonsubsample shearlet transform (NSST) domain. First, we apply NSST to a noisy SAR image to gain low- and high-frequency coefficients. Second, we adopt a learned deep CNN model to eliminate the speckle noise in the low-frequency coefficients, which retains more contour information. Third, we employ CCS to enhance the high-frequency coefficients, which preserves more details of the original SAR image. Finally, we obtain the denoised image by using inverse NSST applied to the denoised coefficients. Compared with state-of-the-art algorithms, the results of the experiment indicate that our method not only achieves better speckle removal performance but also maintains more detailed information retention. Numéro de notice : A2021-397 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2020.3014130 Date de publication en ligne : 18/08/2020 En ligne : https://doi.org/10.1109/TGRS.2020.3014130 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97688
in IEEE Transactions on geoscience and remote sensing > vol 59 n° 5 (May 2021) . - pp 3956 - 3966[article]
Titre : Applied signal processing Type de document : Guide/Manuel Auteurs : Sadasivan Puthusserypady, Auteur Editeur : Boston, Delft : Now publishers Année de publication : 2021 Collection : *NowOpen* Importance : 550 p. ISBN/ISSN/EAN : 978-1-68083-979-1 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] convolution (signal)
[Termes IGN] filtrage du signal
[Termes IGN] modulation de fréquence
[Termes IGN] série de Fourier
[Termes IGN] signal aléatoire
[Termes IGN] transformation de Fourier
[Termes IGN] transformation de HilbertRésumé : (éditeur) Being an inter-disciplinary subject, Signal Processing has application in almost all scientific fields. Applied Signal Processing tries to link between the analog and digital signal processing domains. Since the digital signal processing techniques have evolved from its analog counterpart, this book begins by explaining the fundamental concepts in analog signal processing and then progresses towards the digital signal processing. This will help the reader to gain a general overview of the whole subject and establish links between the various fundamental concepts. While the focus of this book is on the fundamentals of signal processing, the understanding of these topics greatly enhances the confident use as well as further development of the design and analysis of digital systems for various engineering and medical applications. Applied Signal Processing also prepares readers to further their knowledge in advanced topics within the field of signal processing. Note de contenu : 1- Introduction
2- Power and Energy
3- Fourier series
4- Fourier transform
5- Complex signals
6- Analog systems
7- Sampling and digital signals
8- Transform of discrete time signals
9- Fourier spectra of discrete-time signals
10- Digital systems
11- Implementation of digital systems
12- Discrete Fourier transform
13- Fast Fourier transform
14- Design of digital filters
15- Random signals
16- Modulation
17- Power Spectrum EstimationNuméro de notice : 28562 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Manuel de cours DOI : 10.1561/9781680839791 En ligne : http://dx.doi.org/10.1561/9781680839791 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97593
Titre : Pulse compression waveform and filter optimization for spaceborne cloud and precipitation radar Type de document : Article/Communication Auteurs : Robert M. Beauchamp, Auteur ; Simone Tanelli, Auteur ; Eva Peral, Auteur Année de publication : 2017 Article en page(s) : pp 915 - 931 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications
[Termes IGN] analyse de sensibilité
[Termes IGN] effet Doppler
[Termes IGN] forme d'onde
[Termes IGN] image radar
[Termes IGN] impulsion laser
[Termes IGN] modulation de fréquence
[Termes IGN] nuage
[Termes IGN] optimisation (mathématiques)
[Termes IGN] précipitationRésumé : (Auteur) The optimal design of pulse compression waveform/filter pairs for use with near-nadir spaceborne radar in low earth orbit for the observation of clouds and precipitation is discussed. An optimization technique is introduced that considers performance metrics specific to the remote sensing of clouds and precipitation from such platforms. Specifically, the sensitivity of the radar to precipitation and clouds is maximized as close to the ground as required. The sensitivity of the radar near the surface is typically limited by the pulse compression range sidelobes from the surface's echo. Optimization of the waveform/filter pair's performance is facilitated by a time-domain radar scattering model to simulate radar reflectivity range profiles. The presented radar-scattering model accounts for the radar's configuration constraints and platform motion, as well as the spatial distribution and relative motion of the scatterers. In this paper, the optimization of both linear frequency modulation (LFM) and nonlinear frequency modulation (NLFM) waveforms is considered. It is demonstrated that the LFM waveforms provide superior performance over NLFM waveforms for application subject to unmitigated Doppler shifts. Numéro de notice : A2017-145 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2016.2616898 En ligne : http://dx.doi.org/10.1109/TGRS.2016.2616898 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84633
in IEEE Transactions on geoscience and remote sensing > vol 55 n° 2 (February 2017) . - pp 915 - 931[article]
Titre : A GIHS-based spectral preservation fusion method for remote sensing images using edge restored spectral modulation Type de document : Article/Communication Auteurs : Xiran Zhou, Auteur ; Jun Liu, Auteur ; Lei Cao, Auteur ; Qiming Zhou, Auteur ; et al., Auteur Année de publication : 2014 Article en page(s) : pp 16 - 27 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] algorithme de fusion
[Termes IGN] appariement d'histogramme
[Termes IGN] filtrage numérique d'image
[Termes IGN] fusion d'images
[Termes IGN] image multibande
[Termes IGN] modulation de fréquence
[Termes IGN] qualité d'image
[Termes IGN] transformation intensité-teinte-saturationRésumé : (Auteur) High spatial resolution and spectral fidelity are basic standards for evaluating an image fusion algorithm. Numerous fusion methods for remote sensing images have been developed. Some of these methods are based on the intensity–hue–saturation (IHS) transform and the generalized IHS (GIHS), which may cause serious spectral distortion. Spectral distortion in the GIHS is proven to result from changes in saturation during fusion. Therefore, reducing such changes can achieve high spectral fidelity. A GIHS-based spectral preservation fusion method that can theoretically reduce spectral distortion is proposed in this study. The proposed algorithm consists of two steps. The first step is spectral modulation (SM), which uses the Gaussian function to extract spatial details and conduct SM of multispectral (MS) images. This method yields a desirable visual effect without requiring histogram matching between the panchromatic image and the intensity of the MS image. The second step uses the Gaussian convolution function to restore lost edge details during SM. The proposed method is proven effective and shown to provide better results compared with other GIHS-based methods. Numéro de notice : A2014-081 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2013.11.011 En ligne : https://doi.org/10.1016/j.isprsjprs.2013.11.011 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32986
in ISPRS Journal of photogrammetry and remote sensing > vol 88 (February 2014) . - pp 16 - 27[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 081-2014021 RAB Revue Centre de documentation En réserve L003 Disponible
Titre : Triple-frequency GPS precise point positioning with rapid ambiguity resolution Type de document : Article/Communication Auteurs : Jianghui Geng, Auteur ; Yehuda Bock, Auteur Année de publication : 2013 Article en page(s) : 460 p. ; pp 449 - 460 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] modulation de fréquence
[Termes IGN] positionnement ponctuel précis
[Termes IGN] récepteur trifréquence
[Termes IGN] résolution d'ambiguïtéRésumé : (Auteur) At present, reliable ambiguity resolution in real-time GPS precise point positioning (PPP) can only be achieved after an initial observation period of a few tens of minutes. In this study, we propose a method where the incoming triple-frequency GPS signals are exploited to enable rapid convergences to ambiguity-fixed solutions in real-time PPP. Specifically, extra-wide-lane ambiguity resolution can be first achieved almost instantaneously with the Melbourne-Wübbena combination observable on L2 and L5. Then the resultant unambiguous extra-wide-lane carrier-phase is combined with the wide-lane carrier-phase on L1 and L2 to form an ionosphere-free observable with a wavelength of about 3.4 m. Although the noise of this observable is around 100 times the raw carrier-phase noise, its wide-lane ambiguity can still be resolved very efficiently, and the resultant ambiguity-fixed observable can assist much better than pseudorange in speeding up succeeding narrow-lane ambiguity resolution. To validate this method, we use an advanced hardware simulator to generate triple-frequency signals and a high-grade receiver to collect 1-Hz data. When the carrier-phase precisions on L1, L2 and L5 are as poor as 1.5, 6.3 and 1.5 mm, respectively, wide-lane ambiguity resolution can still reach a correctness rate of over 99 % within 20 s. As a result, the correctness rate of narrow-lane ambiguity resolution achieves 99 % within 65 s, in contrast to only 64 % within 150 s in dual-frequency PPP. In addition, we also simulate a multipath-contaminated data set and introduce new ambiguities for all satellites every 120 s. We find that when multipath effects are strong, ambiguity-fixed solutions are achieved at 78 % of all epochs in triple-frequency PPP whilst almost no ambiguities are resolved in dual-frequency PPP. Therefore, we demonstrate that triple-frequency PPP has the potential to achieve ambiguity-fixed solutions within a few minutes, or even shorter if raw carrier-phase precisions are around 1 mm. In either case, we conclude that the efficiency of ambiguity resolution in triple-frequency PPP is much higher than that in dual-frequency PPP. Numéro de notice : A2013-255 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-013-0619-2 Date de publication en ligne : 22/02/2013 En ligne : https://doi.org/10.1007/s00190-013-0619-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32393
in Journal of geodesy > vol 87 n° 5 (May 2013) . - 460 p. ; pp 449 - 460[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-2013051 SL Revue Centre de documentation Revues en salle Disponible PermalinkPermalink
