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Radicella, Sandro Maria
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Radicella, Sandro Maria
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Radicella, Sandro M
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19 results
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- PublicationOpen AccessIonospheric biases correction for coordinates derived from GPS single point positioning(2005)
; ; ; ; ; ;Gende, M.; Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Argentina ;Mohíno Harris, E.; Departamento de Geofísica y Meteorología, Universidad Complutense de Madrid, Spain ;Brunini, C.; Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Argentina ;Radicella, S. M.; Aeronomy and Radiopropagation Laboratory, The Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy ;Herraiz, M.; Departamento de Geofísica y Meteorología, Universidad Complutense de Madrid, Spain; ; ; ; Most GPS users employ low cost receivers. These receivers do not allow users to record the pseudorange that they observe, but the computed coordinates. This work presents an original and simple method to correct ionospheric biases introduced in GPS signals. The originality of this method is based on the fact that no pseudorange is needed to correct the biases, only the calculated coordinates are used. This distinguishes this method from other classic alternatives. This paper evaluates the efficiency of the method with the use of real data.182 493 - PublicationOpen AccessThe improved DGR analytical model of electron density height profile and total electron content in the ionosphere(1995-03)
; ; ;Radicella, S. M.; Atmospheric Physics and Radiopropagation Laboratory, International Centre tor Theoretical Physics, Trieste, Italy ;Zhang, M. L.; Atmospheric Physics and Radiopropagation Laboratory, International Centre tor Theoretical Physics, Trieste, Italy; Tests of the analytical model of the electron density profile originally proposed by G, Di Giovanni and S.M. Radicella (DGR model) have shown the need to introduce improvements in order to obtain a model able to reproduce the ionosphere in a larger spectrum of geophysical and time conditions. The present paper reviews the steps toward such progress and presents the final formulation of the model. It gives also a brief re- view of tests of the improved model done by different authors.657 840 - PublicationOpen AccessScintillations effects on satellite to Earth links for telecommunication and navigation purposes(2004)
; ; ; ; ; ; ;Béniguel, Y.; IEEA, Courbevoie, France ;Forte, B.; The Abdus Salam International Centre for Theoretical Physics (ICTP), Aeronomy and Radiopropagation Laboratory, Trieste, Italy ;Radicella, S. M.; The Abdus Salam International Centre for Theoretical Physics (ICTP), Aeronomy and Radiopropagation Laboratory, Trieste, Italy ;Strangeways, H. J.; University of Leeds, U.K. ;Gherm, V. E.; University of St. Petersburg, Russia ;Zernov, N. N.; University of St. Petersburg, Russia; ; ; ; ; Radio wave scintillations are rapid fluctuations in both amplitude and phase of signals propagating through the atmosphere. GPS signals can be affected by these disturbances which can lead to a complete loss of lock when the electron density strongly fluctuates around the background ionization level at small spatial scales. This paper will present recent improvements to the theoretical Global Ionospheric Scintillation Model (GISM), particularly tailored for satellite based navigation systems such GPS coupled with Satellite Based Augmentation System (SBAS). This model has been improved in order to take into account GPS constellation, signals, and receiver response to ionospheric scintillation environments. A new modelling technique, able to describe the scintillation derived modifications of transionospheric propagating fields is shown. Results from GPS derived experimental measurements performed at high and low magnetic latitudes will show preliminary assessments of the scintillation impact on real receivers and system operations. Nevertheless, comparisons between theoretical scintillation models, such as WBMOD and GISM, with GPS derived experimental data will be shown.333 1128 - PublicationOpen AccessComparison of analytical functions used to describe topside electron density profiles with satellite data(2005)
; ; ; ; ;Fonda, C.; The Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy ;Coïsson, P.; The Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy ;Nava, B.; The Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy ;Radicella, S. M.; The Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy; ; ; Electron density models of the ionosphere use different analytical formulations for the electron density vertical profile in the topside. The present paper compares some single-layer topside analytical descriptions (Chapman, Epstein, modified Epstein used in the NeQuick model) with experimental topside profiles obtained from measurements of IK19 and ISIS2 satellites. The limits of height range and shape for each formulation are described and analyzed and suggestions for the use of multiple layers solution to reproduce experimental results are given.241 740 - PublicationOpen AccessTotal electron content - A key parameterin propagation: measurement and usein ionospheric imaging(2004)
; ; ; ; ; ; ; ; ; ; ;Kersley, L.; University of Wales, Aberystwyth, U.K. ;Malan, D.; University of Wales, Aberystwyth, U.K. ;Pryse, S. E.; University of Wales, Aberystwyth, U.K. ;Cander, L. R.; Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, U.K. ;Bamford, R. A.; Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, U.K. ;Belehaki, A.; National Observatory, Institute for Space Applications and Remote Sensing, P. Penteli, Athens, Greece ;Leitinger, R.; Institute of Physics, Institute for Geophysics, Astrophysics and Meteorology (IGAM), University of Graz, Austria ;Radicella, S. M.; The Abdus Salam International Centre for Theoretical Physics (ICTP), Aeronomy and Radiopropagation Laboratory, Trieste, Italy ;Mitchell, C. N.; University of Bath, U.K. ;Spencer, P. S. J.; University of Bath, U.K.; ; ; ; ; ; ; ; ; The paper reports on a series of studies carried out within the COST 271 Action relating to the measurement and use of Total Electron Content (TEC) of the ionosphere over North West Europe. Total electron content is a very important parameter for the correction of propagation effects on applied radio systems so that it is vital to have confidence in the experimental measurements and the resultant products derived as aids for the practical user. Comparative investigations have been carried out using TEC values from several different sources. It was found that in general there was broad statistical agreement between the data sets within the known limitations of the techniques, though discrepancies were identified linked to steep ionospheric gradients at the onset of geomagnetic storm disturbance and in the vicinity of the main trough. The paper also reviews recent progress in the development of tomographic inversion techniques that use total electron content measurements to image the ionosphere as an aid to various radio systems applications.298 2207 - PublicationOpen AccessComparison of ionospheric scintillation models with experimental data for satellite navigation applications(2005)
; ; ;Forte, B.; The Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy ;Radicella, S. M.; The Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy; A comparison between two of the most used scintillation models and experimental data is presented. The experimental data have been derived from a GPS scintillation monitor developed at Cornell University and placed in Tucuman (Argentina), under the peak of the anomaly. The models used (GISM and WBMOD) have been run for the geophysical conditions corresponding to the measurements. The comparison is done by subdividing the information on the basis of an ionospheric grid of 5°×5° surface square boxes. The comparison has been performed for several local times, from 18 LT until 04 LT. Here, only a few cases of particular interest are shown. The goal is to understand if the models are able to forecast actual scintillation morphology (from the satellite navigation systems point of view) and if they could be used to yield an estimate of scintillation effects on satellite navigation systems.401 604 - PublicationOpen AccessWorst cases for an one-hop high frequency link(2002)
; ; ; ; ;Mirò, G.; Atmospheric Sounding Station «El Arenosillo», National Institute of Aerospace Technology, Magazón, Huelva, Spain ;de la Morena, B. A.; Atmospheric Sounding Station «El Arenosillo», National Institute of Aerospace Technology, Magazón, Huelva, Spain ;Radicella, S. M.; Aeronomy and Radiopropagation Laboratory, Abdus Salam ICTP, Trieste, Italy ;Herraiz, M.; Department of Geophysics and Meteorology, Faculty of Physics, Complutense University, Madrid, Spain; ; ; The characterisation of a HF channel by means of monthly electron density profiles can be complemented with a detailed study of radio propagation «worst cases» on situations with extremes conditions of radiopropagation for a given period. These «worst cases» correspond to conditions that can be identified by means of cumulative distributions of the key parameter f0F2. In this paper, the main parameters of the HF channel: time delay, apogee, elevation angle and transmission frequency with mean and extreme conditions are analysed. The method used to characterise the ionospheric channel is based on ray-tracing techniques.131 168 - PublicationOpen AccessIonospheric topside models compared with experimental electron density profiles(2005)
; ; ;Coïsson, P.; The Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy ;Radicella, S. M.; The Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy; Recently an increasing number of topside electron density profiles has been made available to the scientific community on the Internet. These data are important for ionospheric modeling purposes, since the experimental information on the electron density above the ionosphere maximum of ionization is very scarce. The present work compares NeQuick and IRI models with the topside electron density profiles available in the databases of the ISIS2, IK19 and Cosmos 1809 satellites. Experimental electron content from the F2 peak up to satellite height and electron densities at fixed heights above the peak have been compared under a wide range of different conditions. The analysis performed points out the behavior of the models and the improvements needed to be assessed to have a better reproduction of the experimental results. NeQuick topside is a modified Epstein layer, with thickness parameter determined by an empirical relation. It appears that its performance is strongly affected by this parameter, indicating the need for improvements of its formulation. IRI topside is based on Booker's approach to consider two parts with constant height gradients. It appears that this formulation leads to an overestimation of the electron density in the upper part of the profiles, and overestimation of TEC.210 461 - PublicationOpen AccessEffects of gradients of the electron density on Earth-space communications(2004)
; ; ; ; ; ;Radicella, S. M.; The Abdus Salam International Centre for Theoretical Physics (ICTP7, Aeronomy and Radiopropagation Laboratory, Trieste, Italy ;Nava, B.; The Abdus Salam International Centre for Theoretical Physics (ICTP7, Aeronomy and Radiopropagation Laboratory, Trieste, Italy ;Coïsson, P.; The Abdus Salam International Centre for Theoretical Physics (ICTP7, Aeronomy and Radiopropagation Laboratory, Trieste, Italy ;Kersley, L.; University of Wales, Aberystwyth, U.K. ;Bailey, G. J.; University of Sheffield, U.K.; ; ; ; This paper is a review of the main results achieved in the framework of COST 271 Action Working Group 4, under the activities of the Work Package 4.4. The first topic treated deals with the influence of ionospheric space and time gradients in the slant to vertical and vertical to slant ionospheric delay conversion when the thin shell approximation of the ionosphere is assumed and with the effects of geomagnetic activity on the errors that this conversion introduces. The second topic is related to the comparison of ionospheric topside models with experimental electron density profiles to check the ability of the models to reproduce the observed topside shape and characteristics that determine the electron density gradients. The analysis that has been done allows pointing out the changes needed to improve the models. Finally a third topic covers a model simulation study of the total electron content that can be encountered in GPS-to-geostationary satellite ray paths. It takes into account that the propagation paths for such satellite-to-satellite links are very long and they have the potential to intersect regions of the ionised atmosphere where the electron density is high when the geometry is close to eclipse.251 722 - PublicationOpen AccessComparisons of experimental topside electron concentration profiles with IRI and NeQuick models(2002)
; ; ; ;Coisson, P.; Abdus Salam ICTP, Trieste, Italy ;Radicella, S. M.; Abdus Salam ICTP, Trieste, Italy ;Nava, B.; Abdus Salam ICTP, Trieste, Italy; ; A critical part of the vertical ionospheric electron concentration profile is the region above its maximum (topside ionosphere) and many attempts have been made to model this region because of the limited experimental data available. Recently, many topside electron concentration profiles obtained with the Intercosmos-19 satellite became accessible through the Internet. The period analyzed corresponds to March 1979 - December 1980, a time interval of high solar activity. The present work describes the comparison of these profiles with the IRI and NeQuick model profiles obtained by driving the models with the values of the maximum electron concentration and its height given by the satellite.178 340