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Toward operational compensation of ionospheric effects in SAR interferograms: the split-spectrum method / Giorgio Gomba in IEEE Transactions on geoscience and remote sensing, vol 54 n° 3 (March 2016)
[article]
Titre : Toward operational compensation of ionospheric effects in SAR interferograms: the split-spectrum method Type de document : Article/Communication Auteurs : Giorgio Gomba, Auteur ; Alessandro Parizzi, Auteur ; Francesco De Zan, Auteur Année de publication : 2016 Article en page(s) : pp 1446 - 1461 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications
[Termes IGN] bande L
[Termes IGN] compensation
[Termes IGN] correction ionosphérique
[Termes IGN] image ALOS-PALSAR
[Termes IGN] image radar moirée
[Termes IGN] interféromètrie par radar à antenne synthétique
[Termes IGN] phase
[Termes IGN] relief
[Termes IGN] retard troposphériqueRésumé : (Auteur) The differential ionospheric path delay is a major error source in L-band interferograms. It is superimposed to topography and ground deformation signals, hindering the measurement of geophysical processes. In this paper, we proceed toward the realization of an operational processor to compensate the ionospheric effects in interferograms. The processor should be robust and accurate to meet the scientific requirements for the measurement of geophysical processes, and it should be applicable on a global scale. An implementation of the split-spectrum method, which will be one element of the processor, is presented in detail, and its performance is analyzed. The method is based on the dispersive nature of the ionosphere and separates the ionospheric component of the interferometric phase from the nondispersive component related to topography, ground motion, and tropospheric path delay. We tested the method using various Advanced Land Observing Satellite Phased-Array type L-band synthetic aperture radar interferometric pairs with different characteristics: high to low coherence, moving and nonmoving terrains, with and without topography, and different ionosphere states. Ionospheric errors of almost 1 m have been corrected to a centimeter or a millimeter level. The results show how the method is able to systematically compensate the ionospheric phase in interferograms, with the expected accuracy, and can therefore be a valid element of the operational processor. Numéro de notice : A2016-130 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2015.2481079 En ligne : https://doi.org/10.1109/TGRS.2015.2481079 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80017
in IEEE Transactions on geoscience and remote sensing > vol 54 n° 3 (March 2016) . - pp 1446 - 1461[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 065-2016031 SL Revue Centre de documentation Revues en salle Disponible Effectiveness of observation-domain sidereal filtering for GPS precise point positioning / Christopher Atkins in GPS solutions, vol 20 n° 1 (January 2016)
[article]
Titre : Effectiveness of observation-domain sidereal filtering for GPS precise point positioning Type de document : Article/Communication Auteurs : Christopher Atkins, Auteur ; Marek Ziebart, Auteur Année de publication : 2016 Article en page(s) : pp 111 - 122 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] correction du trajet multiple
[Termes IGN] phase
[Termes IGN] positionnement ponctuel précis
[Termes IGN] propagation ionosphérique
[Termes IGN] séisme
[Termes IGN] variance d'Allan
[Vedettes matières IGN] Traitement de données GNSSRésumé : (Auteur) Sidereal filtering is a technique used to reduce errors caused by multipath in the positioning of static receivers via the Global Positioning System (GPS). It relies upon the receiver and its surrounding environment remaining static from one day to the next and takes advantage of the approximately sidereal repeat time of the GPS constellation geometry. The repeating multipath error can thus be identified, usually in the position domain, and largely removed from the following day. We describe an observation-domain sidereal filter algorithm that operates on undifferenced ionospheric-free GPS carrier phase measurements to reduce errors caused by multipath. It is applied in the context of high-rate (1 Hz) precise point positioning of a static receiver. An observation-domain sidereal filter (ODSF) is able to account for the slightly different repeat times of each GPS satellite, unlike a position-domain sidereal filter (PDSF), and can hence be more effective at reducing high-frequency multipath error. Using 8-h long datasets of GPS measurements from two different receivers with different antenna types and contrasting environments, the ODSF algorithm is shown overall to yield a position time series 5–10 % more stable, in terms of Allan deviation, than a PDSF over nearly all time intervals below about 200 s in length. This may be particularly useful for earthquake and tsunami early warning systems where the accurate measurement of small displacements of the ground over the period of just a few minutes is crucial. However, the sidereal filters are also applied to a third dataset during which two short episodes of particularly high-frequency multipath error were identified. These two periods are analyzed in detail and illustrate the limitations of using sidereal filters with important implications for other methods of correcting for multipath at the observation level. Numéro de notice : A2016-605 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-015-0473-1 En ligne : http://dx.doi.org/10.1007/s10291-015-0473-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81806
in GPS solutions > vol 20 n° 1 (January 2016) . - pp 111 - 122[article]Entwicklung einer direkten Georeferenzierungseinheit zur Positions- und Orientierungbestimmung leichter UAVs in Eichzeit / Christian Eling (2016)
Titre : Entwicklung einer direkten Georeferenzierungseinheit zur Positions- und Orientierungbestimmung leichter UAVs in Eichzeit Type de document : Thèse/HDR Auteurs : Christian Eling, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 2016 Collection : DGK - C, ISSN 0065-5325 num. 788 Importance : 107 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-5200-0 Note générale : bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique
[Termes IGN] drone
[Termes IGN] géoréférencement direct
[Termes IGN] GPS-INS
[Termes IGN] magnétomètre
[Termes IGN] onde porteuse
[Termes IGN] photogrammétrie aérienne
[Termes IGN] semis de points
[Termes IGN] système de numérisation mobileRésumé : (auteur) In recent years, Unmanned Aerial Vehicles (UAVs) have been used increasingly as mobile mapping platforms for kinematic applications in the field of geodesy. For this purpose a UAV is usually equipped with a mapping sensor, such as a camera or a laserscanner. A major step to make the collected data useful for surveying applications is the georeferencing, which associates the images or range measurements and the derived products (point clouds, orthofotos, 3D models) with a spatial reference. In this dissertation the development of a direct georeferencing system for real-time position and attitude determination of lightweight UAVs is presented. The term „direct" means that the georeferencing is based on an onboard multi-sensor system. Sensors, which are typically used in this context, are GPS (Global Positioning System) receivers, inertial sensors and magnetometers. For geodetic UAV-applications Micro-UAVs are usually applied, which have a weight limit of 5 kg. Therefore, weight, size and power supply constraints play an important role here. As a result of these limitations inertial sensors based on MEMS (Micro Electro Mechanical System) technology are mostly used. This technology enables the compliance with size and weight limits, but it also leads to significant drift effects in the position and attitude determination after a short period of time. To bound these drift effects and to be able to provide high accuracies (e.g. position: 5 cm, attitude: 0.5 deg) in the direct georeferencing of a Micro-UAV, a high availability of precise GPS carrier phase measurements is crucially important. As a consequence the following aspects will be addressed in this dissertation:
• GPS carrier phase measurements are ambiguous by an unknown number of integer cycles. These so called ambiguities have to be resolved after every loss of lock of the satellite signals to fully exploit the high accuracies of the carrier phase observables. Since the satellite signals are interrupted frequently during kinematic applications, procedures are developed, implemented and evaluated, which enable a fast ambiguity resolution and allow for a high availability of CPS carrier phase measurements under challenging GPS measurement conditions.
• With the aim to realize high accuracies and a high robustness, redundant information from several sensors is integrated in a sensible manner in sensorfusion algorithms In order to be able to deal with challenging GPS measurement conditions, the sensorfusion is realized at the level of GPS raw measurements in a tightly-coupled GPS/MEMS-IMU integration algorithm. In this way GPS carrier phase measurements can even be used, if less than four satellites are visible, which also increases the availability of a precise position estimation. The accuracy improvements of a tightly-coupled over a loosely-coupled integration during challenging GPS measurement conditions are investigated.
• The algorithms are implemented on a multi-sensor system, which has been developed for the direct georeferencing of lightweight UAVs in this dissertation. Results of flight tests and measurements with a portable test system demonstrate that the developed direct georeferencing system leads to position accuracies of less than 5 cm and attitude (roll, pitch, yaw) accuracies of less than 0.2 deg, if GPS carrier-phase measurements are available. Overall, this dissertation gives detailed insights into the development of algorithms and a multi-sensor system for the direct georeferencing of lightweight UAVs in real-time. The findings gained in this thesis are not only valid for the position and attitude determination of lightweight UAVs but also for other mobile platforms, such as cars, ships, airplanes or rail-borne vehicles. Therefore, this work makes an important contribution to a current trend in the field of engineering geodesy, where mapping, monitoring and also setting-out is more and more realized using mobile mapping systems.Numéro de notice : 17380 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Thèse étrangère Note de thèse : Dissertation : : Rheinische Friedrich-Wilhelms-Universität Bonn : 2016 DOI : sans En ligne : https://dgk.badw.de/fileadmin/user_upload/Files/DGK/docs/c-788.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84793
Titre : Theoretical and practical aspects of high-rate GNSS geodetic observations Type de document : Thèse/HDR Auteurs : Simon Häberling, Auteur Editeur : Zurich : Schweizerischen Geodatischen Kommission / Commission Géodésique Suisse Année de publication : 2016 Autre Editeur : Zurich : Eidgenossische Technische Hochschule ETH - Ecole Polytechnique Fédérale de Zurich EPFZ Collection : Geodätisch-Geophysikalische Arbeiten in der Schweiz, ISSN 0257-1722 num. 95 Importance : 212 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-908440-41-3 Note générale : bibliographie
thesis submitted to attain the degree of doctor of sciences of ETH ZurichLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] bruit thermique
[Termes IGN] erreur de positionnement
[Termes IGN] filtrage du signal
[Termes IGN] fréquence
[Termes IGN] onde sismique
[Termes IGN] phase
[Termes IGN] source d'erreurIndex. décimale : 30.61 Systèmes de Positionnement par Satellites du GNSS Résumé : (auteur) The main goal of the thesis is the thorough investigation and quantification of GNSS observation errors in the frequency range above 1 Hz while going to the limit of the actual receiver technology with sampling rates up to 100 sps. The potential GNSS errors in this high-frequency band are mainly caused by receiver internal error sources. Due to theoretical considerations and empirical results derived from GNSS observations of almost all available carrier signals, the carrier jitter induced by thermal noise and the receiver frequency response produced by highly dynamic motions could be detected as the two most dominant disturbances affecting high-rate GNSS observations above 1 Hz.
The zero-baseline configuration (splitting the signal from one antenna to two receivers) allowed a detailed study of the carrier phase jitter and correlations between subsequent epochs dependent on different GNSS signal characteristics and baseband parameters. The size of the carrier phase jitter is directly determined by the carrier-to-noise density ratio at baseband and the corresponding loop bandwidth. Especially encrypted code sequences have a strong influence on the quality of the corresponding carrier phase component due to signal strength consuming decryption algorithms. The final consequences are a higher carrier jitter and a stronger frequency response due to the necessary PLL guiding by the strong loop signals such as GPS L1 derived from the C/A component. The impact of this higher carrier phase jitter plays a dominant role for the overall noise in the highfrequency spectrum while building the ionosphere-free linear combination. This has been demonstrated using a zero-baseline, but also a 10 m and 110 km baseline. The carrier phase jitter induced by thermal noise defines the noise level above 1 Hz. This high-frequency noise is therefore baseline independent. No significant differences between a baseline of 10 m and 110 km could be detected considering the signal spectrum between 0.01 Hz and 50 Hz.
For the determination and analysis of the GNSS errors caused by high-frequency motions an experimental setup has been established consisting of a single-axis shake table as motion generator and of a well-known ground-truth defined by inductive displacement transducers. The ground-truth was validated by a strong motion seismometer with a flat frequency response carried on the shake table. With an additional precise time synchronization between all the sensors, the experiment with a mounted GNSS antenna on the shake table enabled the determination of the GNSS receiver frequency response between 1 and 20 Hz. Using different receiver types and PLL bandwidths, the amplitudes even at 3 Hz can be overestimated by about 50%, above 10 Hz also an overestimation can be observed or a reduction by well over half of the amplitude. Not only the amplitude is affected, but also the signal phase with errors between 30 and 90 degrees. This demonstrates the importance of a detailed knowledge of the loop parameters for an assessment of the expected errors, but also for applying an inverse filter in order to correct the GNSS receiver frequency response based on a simple digital PLL model. These results are relevant for all applications with strong dynamics using high-rate GNSS, such as structural health monitoring, machine guidance, navigation, and ionosphere scintillation studies.
Further, seismological implications and the potential contribution of high-rate GNSS to seismology has been evaluated. Based on a moderate synthetic earthquake expected for Switzerland generated on the shake table, the sensitivity of high-rate GPS to highfrequency seismic signals using a realistic baseline length could be tested. Additionally, the receiver response has been simulated for real earthquakes in order to demonstrate the displacement errors caused by the response.Note de contenu : 1- Introduction
2- GNSS Signal Structure
3- GNSS Receiver Architecture
4- Carrier Tracking Modeling
5- Analysis of the GNSS Signal Noise
6- Shake Table Experiments
7- GNSS Receiver Response
8- Implications on Seismology and other Applications
9- Conclusions and OutlookNuméro de notice : 17461 Affiliation des auteurs : non IGN Autre URL associée : https://doi.org/10.3929/ethz-a-010592866 Thématique : POSITIONNEMENT Nature : Thèse étrangère Note de thèse : thèse : Sciences : ETHZ : 2015 DOI : 10.3929/ethz-a-010592866 En ligne : https://www.sgc.ethz.ch/sgc-volumes/sgk-95.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89687 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 17461-01 30.61 Livre Centre de documentation Géodésie Disponible Snow depth estimation based on multipath phase combination of GPS triple-frequency signals / Kegen Yu in IEEE Transactions on geoscience and remote sensing, vol 53 n° 9 (September 2015)
[article]
Titre : Snow depth estimation based on multipath phase combination of GPS triple-frequency signals Type de document : Article/Communication Auteurs : Kegen Yu, Auteur ; Wei Ban, Auteur ; Xiaohong Zhang, Auteur ; Xingwang Yu, Auteur Année de publication : 2015 Article en page(s) : pp 5100 - 5109 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] données GPS
[Termes IGN] épaisseur
[Termes IGN] manteau neigeux
[Termes IGN] mesurage de phase
[Termes IGN] mesure géométrique
[Termes IGN] onde porteuse
[Termes IGN] positionnement par GNSS
[Termes IGN] récepteur trifréquence
[Termes IGN] réflectométrie par GNSSRésumé : (Auteur) Snow is important to the ecological and climate systems; however, current snowfall and snow depth in situ observations are only available sparsely on the globe. By making use of the networks of Global Positioning System (GPS) stations established for geodetic applications, it is possible to monitor snow distribution on a global scale in an inexpensive way. In this paper, we propose a new snow depth estimation approach using a geodetic GPS station, multipath reflectometry and a linear combination of phase measurements of GPS triple-frequency (L1, L2, and L5) signals. This phase combination is geometry free and is not affected by ionospheric delays. Analytical linear models are first established to describe the relationship between antenna height and spectral peak frequency of combined phase time series, which are calculated based on theoretical formulas. When estimating snow depth in real time, the spectral peak frequency of the phase measurements is obtained, and then the model is used to determine snow depth. Two experimental data sets recorded in two different environments were used to test the proposed method. The results demonstrate that the proposed method shows an improvement with respect to existing methods on average. Numéro de notice : A2015-553 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2015.2417214 En ligne : https://doi.org/10.1109/TGRS.2015.2417214 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77588
in IEEE Transactions on geoscience and remote sensing > vol 53 n° 9 (September 2015) . - pp 5100 - 5109[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 065-2015091 SL Revue Centre de documentation Revues en salle Disponible Assessment of high-rate GPS using a single-axis shake table / Simon Häberling in Journal of geodesy, vol 89 n° 7 (July 2015)PermalinkPermalinkInterferometric phase image estimation via sparse coding in the complex domain / Hao Hongxing in IEEE Transactions on geoscience and remote sensing, vol 53 n° 5 (mai 2015)PermalinkCarrier-phase ambiguity resolution: Handling the biases for improved triple-frequency PPP convergence / Denis Laurichesse in GPS world, vol 26 n° 4 (April 2015)PermalinkRelating statistical characteristics of cross-polarized phase difference to speckle noise / Huimin Li in Journal of applied remote sensing, vol 9 (2015)Permalink3-Pol polarimetric weather measurements with agile-beam phased-array radars / Verónica Santalla del Rio in IEEE Transactions on geoscience and remote sensing, vol 52 n° 9 Tome 2 (September 2014)PermalinkUAV shipboard landing with RTK: a carrier phase compensates for wind and wave motion / Chiu-Jung Huang in GPS world, vol 25 n° 5 (May 2014)PermalinkPermalinkIntegrated denoising and unwrapping of INSAR phase based on Markov random fields / Runpu Chen in IEEE Transactions on geoscience and remote sensing, vol 51 n° 8 (August 2013)PermalinkDirectionally adaptive filter for synthetic aperture radar interferometric phase images / S. Fu in IEEE Transactions on geoscience and remote sensing, vol 51 n° 1 Tome 2 (January 2013)Permalink