Academic literature on the topic 'Ionospheric techniques'
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Journal articles on the topic "Ionospheric techniques"
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Walker, I. K., J. A. T. Heaton, L. Kersley, C. N. Mitchell, S. E. Pryse, and M. J. Williams. "EISCAT verification in the development of ionospheric tomography." Annales Geophysicae 14, no. 12 (1996): 1413–21. http://dx.doi.org/10.1007/s00585-996-1413-8.
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Abstract. This paper highlights the important role played by the EISCAT radar for verification in the development of tomographic techniques to produce images of ionospheric electron density. A brief review is given of some of the stages in the application of tomographic reconstruction techniques to the ionosphere. Results are presented to illustrate the effectiveness of the method in imaging ionospheric structures at high latitudes. In addition, the results include the first tomographic image of the ionosphere for a region extending from mid-latitudes over mainland Scandinavia to high latitudes above Svalbard.
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Prajapati, Parinda, and Nimisha Patel. "Ionospheric Model Development for Indian Region: A Survey Paper." ECS Transactions 107, no. 1 (2022): 11075–82. http://dx.doi.org/10.1149/10701.11075ecst.
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Ionosphere’s role is most important in vigorous satellite communication for the navigation positional correctness purpose. Ionosphere contains diverse layers reliant on its electron density with altitude in the layer. There are various ionospheric models to forecast electron density with temporal resolutions cited by literatures. GPS data is frequently used by these models. So, the necessity is a prerequisite of evolving ionospheric models with different time duration for low latitudes of India. Also, an ionosphere tomography is considered as an ill-posed problem. Ionospheric TEC found simultaneously at numerous locations can be preserved with several algorithms to conquer electron density. This research is proposed for evolving a model to forecast 3D tomography of total electron density for the whole Indian region. Mainly used satellite data can be collected by various means. The management of vast statistics are planned by using data mining techniques and artificial neural network techniques for estimation. This paper is an outcome of detailed research on ionospheric model development.
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Jin, Shuanggen, J. U. Park, J. L. Wang, B. K. Choi, and P. H. Park. "Electron Density Profiles Derived From Ground-Based GPS Observations." Journal of Navigation 59, no. 3 (2006): 395–401. http://dx.doi.org/10.1017/s0373463306003821.
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Nowadays GPS is widely used to monitor the ionosphere. However, the current results from ground-based GPS observations only provide some information on the horizontal structure of the ionosphere, and are extremely restricted in mapping its vertical structure. In this paper, tomography reconstruction technique was used to image 3D ionospheric structure with ground-based GPS. The first result of the 3D images of the ionospheric electron density distribution in South Korea has been generated from the permanent Korean GPS Network (KGN) data. Compared with the profiles obtained by independent ionosondes at or near the GPS receiver stations, the electron density profiles obtained by the GPS tomographic construction method are in better agreement, showing the validity of the GPS ionospheric tomographic reconstruction. It has also indicated that GPS-based 3D ionospheric mapping has the potential to complement other expensive observing techniques in ionospheric mapping, such as ionosondes and radar.
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Bae, Tae-Suk, and Minho Kim. "Performance Analysis of Network-RTK Techniques for Drone Navigation considering Ionospheric Conditions." Journal of Sensors 2018 (2018): 1–8. http://dx.doi.org/10.1155/2018/5154697.
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Recently, an accurate positioning has become the kernel of autonomous navigation with the rapid growth of drones including mapping purpose. The Network-based Real-time Kinematic (NRTK) system was predominantly used for precision positioning in many fields such as surveying and agriculture, mostly in static mode or low-speed operation. The NRTK positioning, in general, shows much better performance with the fixed integer ambiguities. However, the success rate of the ambiguity resolution is highly dependent on the ionospheric condition and the surrounding environment of Global Navigation Satellite System (GNSS) positioning, which particularly corresponds to the low-cost GNSS receivers. We analyzed the effects of the ionospheric conditions on the GNSS NRTK, as well as the possibility of applying the mobile NRTK to drone navigation for mapping. Two NRTK systems in operation were analyzed during a period of high ionospheric conditions, and the accuracy and the performance were compared for several operational cases. The test results show that a submeter accuracy is available even with float ambiguity under a favorable condition (i.e., visibility of the satellites as well as stable ionosphere). We still need to consider how to deal with ionospheric disturbances which may prevent NRTK positioning.
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Amm, O., A. Aruliah, S. C. Buchert, et al. "Towards understanding the electrodynamics of the 3-dimensional high-latitude ionosphere: present and future." Annales Geophysicae 26, no. 12 (2008): 3913–32. http://dx.doi.org/10.5194/angeo-26-3913-2008.
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Abstract. Traditionally, due to observational constraints, ionospheric modelling and data analysis techniques have been devised either in one dimension (e.g. along a single radar beam), or in two dimensions (e.g. over a network of magnetometers). With new upcoming missions like the Swarm ionospheric multi-satellite project, or the EISCAT 3-D project, the time has come to take into account variations in all three dimensions simultaneously, as they occur in the real ionosphere. The link between ionospheric electrodynamics and the neutral atmosphere circulation which has gained increasing interest in the recent years also intrinsically requires a truly 3-dimensional (3-D) description. In this paper, we identify five major science questions that need to be addressed by 3-D ionospheric modelling and data analysis. We briefly review what proceedings in the young field of 3-D ionospheric electrodynamics have been made in the past to address these selected question, and we outline how these issues can be addressed in the future with additional observations and/or improved data analysis and simulation techniques. Throughout the paper, we limit the discussion to high-latitude and mesoscale ionospheric electrodynamics, and to directly data-driven (not statistical) data analysis.
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Hughes, J. M., W. A. Bristow, R. A. Greenwald, and R. J. Barnes. "Determining characteristics of HF communications links using SuperDARN." Annales Geophysicae 20, no. 7 (2002): 1023–30. http://dx.doi.org/10.5194/angeo-20-1023-2002.
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Abstract. Space weather effects can strongly influence high-frequency (HF) communications by changing the ionospheric environment through which the radio waves propagate. Since many systems utilize HF communications, the ability to make real-time assessments of propagation conditions is an important part of space weather monitoring systems. In this paper, we present new techniques for measuring high-latitude HF communications link parameters using data from SuperDARN radars. These techniques use ground-scatter returns to define the variation in skip distance with frequency. From these data, the maximum usable frequency (MUF) as a function of range is determined and ionospheric critical frequencies are estimated. These calculations are made in near-real-time and the results are made available on the World Wide Web. F-region critical frequencies calculated using this method show good agreement with ionosonde data.Key words. Ionosphere (active experiments; instruments and techniques) – Radio science (ionospheric propagation)
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Chan, A. H. Y., and P. S. Cannon. "Nonlinear forecasts of ƒ<i>o</i>F2: variation of model predictive accuracy over time." Annales Geophysicae 20, no. 7 (2002): 1031–38. http://dx.doi.org/10.5194/angeo-20-1031-2002.
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Abstract. Space weather effects can strongly influence high-frequency (HF) communications by changing the ionospheric environment through which the radio waves propagate. Since many systems utilize HF communications, the ability to make real-time assessments of propagation conditions is an important part of space weather monitoring systems. In this paper, we present new techniques for measuring high-latitude HF communications link parameters using data from SuperDARN radars. These techniques use ground-scatter returns to define the variation in skip distance with frequency. From these data, the maximum usable frequency (MUF) as a function of range is determined and ionospheric critical frequencies are estimated. These calculations are made in near-real-time and the results are made available on the World Wide Web. F-region critical frequencies calculated using this method show good agreement with ionosonde data.Key words. Ionosphere (active experiments; instruments and techniques) – Radio science (ionospheric propagation)
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Pimenta, A. A., P. R. Fagundes, Y. Sahai, J. A. Bittencourt, and J. R. Abalde. "Equatorial F-region plasma depletion drifts: latitudinal and seasonal variations." Annales Geophysicae 21, no. 12 (2003): 2315–22. http://dx.doi.org/10.5194/angeo-21-2315-2003.
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Abstract. The equatorial ionospheric irregularities have been observed in the past few years by different techniques (e.g. ground-based radar, digisonde, GPS, optical instruments, in situ satellite and rocket instrumentation), and its time evolution and propagation characteristics can be used to study important aspects of ionospheric dynamics and thermosphere-ionosphere coupling. At present, one of the most powerful optical techniques to study the large-scale ionospheric irregularities is the all-sky imaging photometer system, which normally measures the strong F-region nightglow 630 nm emission from atomic oxygen. The monochromatic OI 630 nm emission images usually show quasi-north-south magnetic field-aligned intensity depletion bands, which are the bottomside optical signatures of large-scale F-region plasma irregularities (also called plasma bubbles). The zonal drift velocities of the plasma bubbles can be inferred from the space-time displacement of the dark structures (low intensity regions) seen on the images. In this study, images obtained with an all-sky imaging photometer, using the OI 630 nm nightglow emission, from Cachoeira Paulista (22.7° S, 45° W, 15.8° S dip latitude), Brazil, have been used to determine the nocturnal monthly and latitudinal variation characteristics of the zonal plasma bubble drift velocities in the low latitude (16.7° S to 28.7° S) region. The east and west walls of the plasma bubble show a different evolution with time. The method used here is based on the western wall of the bubble, which presents a more stable behavior. Also, the observed zonal plasma bubble drift velocities are compared with the thermospheric zonal neutral wind velocities obtained from the HWM-90 model (Hedin et al., 1991) to investigate the thermosphere-ionosphere coupling. Salient features from this study are presented and discussed.Key words. Ionosphere (ionosphere-atmosphere interactions; ionospheric irregularities; instruments and techniques)
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Provan, G., T. K. Yeoman, S. E. Milan, J. M. Ruohoniemi, and R. Barnes. "An assessment of the "map-potential" and "beam-swinging" techniques for measuring the ionospheric convection pattern using data from the SuperDARN radars." Annales Geophysicae 20, no. 2 (2002): 191–202. http://dx.doi.org/10.5194/angeo-20-191-2002.
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Abstract. The SuperDARN HF coherent scatter radars (Greenwald et al., 1995) provide line-of-sight (l-o-s) velocity measurements of ionospheric convection flow over the polar regions of the northern and southern hemispheres. A number of techniques have been developed in order to obtain 2-D plasma flow vectors from these l-o-s observations. This study entails a comparison of the ionospheric flow vectors derived using the "map-potential", and "beam-swinging" techniques with the vectors derived using the "merging" technique. The merging technique is assumed to be the most accurate method of deriving local flow vectors from l-o-s velocities. We can conclude that the map-potential model is significantly more successful than the beam-swinging technique at estimating both the magnitude and the direction of the large-scale ionospheric convection flow vectors. The quality of the fit is dependent on time of day, with vectors observed at low latitudes in the dawn sector agreeing most closely with the merged vector flow pattern.Key words. Ionosphere (plasma convection; instruments and techniques) – Radio science (instruments and techniques)
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Le Roux, Y. M., J. Ménard, J. P. Jolivet, and P. J. Davy. "<i>Letter to the Editor:</i> SCIPION, a new flexible ionospheric sounder in Senegal." Annales Geophysicae 16, no. 6 (1998): 738–42. http://dx.doi.org/10.1007/s00585-998-0738-x.
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Abstract. SCIPION is a new state of the art digital sounder that has been devoloped by France Telecom-CNET for ionospheric monitoring and research. Extensive data processing using DSP technology has resulted in a low power, low cost and full featured system for both vertical and oblique soundings. A SCIPION system is in the process of being installed in Dakar, Senegal, to study HF propagation in the sub-equatorial ionosphere. However, preliminary results have still been obtained during experiments wit a prototype system. In this paper, the system is described and some illustrative examples of its capabilities are shown.Keywords. Ionosphere (Equatorial ionosphere, Instruments and Techniques) &amp;#x22C5 Radio science (ionospheric propagation).
Dissertations / Theses on the topic "Ionospheric techniques"
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Brosie, Kayla Nicole. "Ionospheric Scintillation Prediction, Modeling, and Observation Techniques for the August 2017 Solar Eclipse." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78710.
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A full solar eclipse is going to be visible from a range of states in the contiguous United States on August 21, 2017. Since the atmosphere of the Earth is charged by the sun, the blocking of the sunlight by the moon may cause short term changes to the atmosphere, such as density and temperature alterations. There are many ways to measure these changes, one of these being ionospheric scintillation. Ionospheric scintillation is rapid amplitude and phase fluctuations of signals passing through the ionosphere caused by electron density irregularities in the ionosphere. At mid-latitudes, scintillation is not as common of an occurrence as it is in equatorial or high-altitude regions. One of the theories that this paper looks into is the possibility of the solar eclipse producing an instability in the ionosphere that will cause the mid-latitude region to experience scintillations that would not normally be present. Instabilities that could produce scintillation are reviewed and altered further to model similar conditions to those that might occur during the solar eclipse. From this, the satellites that are being used are discuses, as is hardware and software tools were developed to record the scintillation measurements. Although this work was accomplished before the eclipse occurred, measurement tools were developed and verified along with generating a model that predicted if the solar eclipse will produce an instability large enough to cause scintillation for high frequency satellite downlinks.<br>Master of Science
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Locubiche-Serra, Sergi. "Robust Carrier Tracking Techniques for GNSS Receivers affected by Ionospheric Scintillation." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/668304.
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Las tecnologías de posicionamiento por satélite (GNSS, del inglés global navigation satellite systems) se han convertido en una herramienta indispensable en diferentes ámbitos de nuestra sociedad moderna. Algunos ejemplos de aplicaciones son el posicionamiento y la navegación en entornos terrestre, marítimo y aéreo, así como usos destinados a la agricultura, topografía o aplicaciones de sincronización precisa en sistemas de telecomunicaciones o finanzas. El módulo de tracking es una de las etapas centrales para mantener los receptores alineados con los satélites, y hasta ahora se han empleado técnicas de tracking convencionales de fácil implementación que son suficientes para operar en escenarios con unas condiciones de trabajo favorables. Sin embargo, en los últimos años, el éxito de GNSS en entornos a cielo abierto ha propiciado su expansión hacia aplicaciones en escenarios más exigentes, tales como cañones urbanos o interiores. La tendencia es dotar a los terminales móviles (smartphones) de capacidades de posicionamiento en entornos en donde se enfrentan a nuevos retos tecnológicos dados por los problemas de propagación que abundan. En este sentido, el centelleo ionosférico (ionospheric scintillation en inglés) es uno de los problemas que degradan las prestaciones de los receptores, particularmente en zonas ecuatoriales y a altas latitudes. Es un efecto que introduce rápidas variaciones aleatorias en la fase y la potencia de la señal útil, y tiene un efecto perjudicial precisamente en la etapa de tracking del receptor.
El objetivo de esta tesis es diseñar y desarrollar nuevas técnicas para el tracking robusto de señales GNSS afectadas por el efecto de centelleo ionosférico. La propuesta que se presenta está basada en el uso de técnicas de filtrado de Kalman, y las contribuciones principales de esta tesis son tres. En primer lugar se estudia el efecto de centelleo ionosférico y el tracking de la dinámica del receptor a pesar de su presencia. Diseñamos un filtro de Kalman con una formulación híbrida que permite monitorizar ambas contribuciones por separado de manera robusta. Esto surge de realizar un análisis detallado del centelleo ionosférico en el que se concluye que las variaciones de fase se pueden caracterizar a través de procesos autoregresivos, los cuales se pueden tratar mediante el filtro de Kalman de manera natural. En segundo lugar se diseñan técnicas de filtrado de Kalman adaptativas que permiten ajustar su ancho de banda en función de las condiciones de centelleo, las cuales suelen ser variantes en el tiempo en la práctica. Esta parte incluye un detector de presencia de centelleo, un estimador en tiempo real de los parámetros del modelo autoregresivo, y una implementación para lidiar con las atenuaciones no lineales introducidas por el mismo centelleo. El funcionamiento de las técnicas propuestas se valida posteriormente mediante una campaña extensiva de simulaciones utilizando tanto datos sintéticos como datos reales de centelleo ionosférico, y se cuantifica la región de ganancia respecto a las técnicas convencionales. Por último se propone un innovador método para derivar expresiones para la denominada cota Bayesiana de Cramér-Rao (BCRB, del inglés Bayesian Cramér-Rao bound) que permiten caracterizar el comportamiento de los filtros de Kalman de manera cerrada. Esto supone una contribución a la literatura de gran interés práctico para diseñar filtros de Kalman para cualquier tipo de aplicación.<br>Global Navigation Satellite Systems (GNSS) have become an indispensable tool in different areas in our modern society for positioning purposes using radio-frequency ranging signals. Some application examples are the positioning and navigation in ground, maritime and aviation environments, as well as their use in agriculture, surveying and precise timing and synchronization in communication systems and finances. The tracking stage is one of the core tasks within a GNSS receiver to keep aligned with the satellites and, to date, most receivers equip conventional tracking techniques with ease of implementation that suffice to operate in environments with favorable working conditions. However, in the recent years, the success of GNSS in open-sky environments has led to the emergence of applications that expand toward scenarios with harsher conditions, such as urban canyons and soft-indoor environments. The trend is to provide user mobile terminals such as smartphones with positioning capabilities in scenarios where receivers face new technological challenges owing to the abounding propagation impairments. In this sense, the so-called ionospheric scintillation is one of the issues degrading the performance of GNSS receivers, particularly in equatorial regions and at high latitudes. It introduces rapid carrier phase and signal power variations, and has a detrimental effect particularly onto the tracking stage.
The objective of this thesis is to design and develop new techniques for the robust tracking of GNSS signals affected by ionospheric scintillation disturbances. The presented approach is based on the use of Kalman filtering techniques, and the main contributions of the thesis are three. First, the analysis of ionospheric scintillation and the tracking of carrier dynamics despite the presence of the former. We design a Kalman filter with a hybrid formulation that allows the robust monitoring of both contributions separately. This arises from carrying out a detailed analysis of ionospheric scintillation which concludes that scintillation phase variations can be characterized through autoregressive processes, and thus be dealt with within the Kalman filter in a natural manner. Second, the design of adaptive Kalman filter-based techniques that allow self-adjusting their loop bandwidth to the actual scintillation conditions, which are rather time-varying in practice. This part includes a scintillation detector, a real-time estimator of the autoregressive model parameters, and an implementation to address the problem of non-linear signal amplitude attenuation introduced by scintillation itself. The goodness of the proposed techniques is later validated by carrying out an extensive simulation campaign using both synthetic data and real scintillation time series, and the outperformance region with respect to conventional tracking techniques is quantified. Third, a novel method for the derivation of expressions for the termed Bayesian Cramér-Rao bound (BCRB), which allow characterizing the behavior of Kalman filters in a closed-form manner, thus becoming a contribution to the literature of practical usefulness to design Kalman filters for any kind of application.
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ROMERO, GAVIRIA RODRIGO MANUEL. "Estimation Techniques and Mitigation Tools for Ionospheric effects on GNSS Receivers." Doctoral thesis, Politecnico di Torino, 2015. http://hdl.handle.net/11583/2616928.
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Navigation is defined as the science of getting a craft or person from one place to another. The development of radio in the past century brought fort new navigation aids that enabled users, or rather their receivers, to compute their position with the help of signals from one or more radio-navigation system . The U.S. Global Positioning System (GPS) was envisioned as a satellite system for three-dimensional position and velocity determination fulfilling the following key attributes: global coverage, continuous/all weather operation, ability to serve high-dynamic platforms, and high accuracy. It represents the fruition of several technologies, which matured and came together in the second half of the 20th century. In particular, stable space-born platforms, ultra-stable atomic frequency standards, spread spectrum signaling, and microelectronics are the key developments in the realization and success of GPS.
While GPS was under development, the Soviet Union undertook to develop a similar system called GLObalnaya NAvigatsionnaya Sputnikovaya Sistema (GLONASS). Both GLONASS and GPS were designed primarily for the military, but have transitioned in the past decades towards providing civilian and Safety-of-Life services as well. Other Global Navigation Satellite Systems (GNSS) are now being developed and deployed by governments, international consortia, and commercial interests. Among these are the European system Galileo and the Chinese system Beidou. Other regional systems are the Japanese Quasi-Zenith Satellite System and the Indian Gagan.
GNSS have become a crucial component in countless modern systems, e.g. in telecommunication, navigation, remote sensing, precise agriculture, aviation and timing. One of the main threats to the reliable and safe operation of GNSS are the variable propagation conditions encountered by GNSS signals as they pass through the upper atmosphere of the Earth. In particular, irregular concentration of electrons in the ionosphere induce fast fluctuations in the amplitude and phase of GNSS signals called scintillations. The latter can greatly degrade the performance of GNSS receivers, with consequent economical impacts on service providers and users of high performance applications. New GNSS navigation signals and codes are expected to help mitigate such effects, although to what degree is still unknown. Furthermore, these new technologies will only come on line incrementally over the next decade as new GNSS satellites become operational. In the meantime, GPS users who need high performance navigation solution, e.g., offshore drilling companies, might be forced to postpone operations for which precision position knowledge is required until the ionospheric disturbances are over. For this reason continuous monitoring of scintillations has become a priority in order to try to predict its occurrence. Indeed, it is a growing scientific and industrial activity.
However, Radio Frequency (RF) Interference from other telecommunication systems might threaten the monitoring of scintillation activity. Currently, the majority of the GNSS based application are highly exposed to unintentional or intentional interference issues. The extremely weak power of the GNSS signals, which is actually completely buried in the noise floor at the user receiver antenna level, puts interference among the external error contributions that most degrade GNSS performance. It is then of interest to study the effects these external systems may have on the estimation of ionosphere activity with GNSS. In this dissertation, we investigate the effect of propagation issues in GNSS, focusing on scintillations, interference and the joint effect of the two phenomena.
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Bergadà, Caramés Pau. "Oblique Sounding and HF Communication Techniques for Very Long Haul Ionospheric Links." Doctoral thesis, Universitat Ramon Llull, 2015. http://hdl.handle.net/10803/285837.
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El sistema de comunicació ràdio d’alta freqüència (HF, en anglès) és usat arreu del món per agències governamentals i no governamentals sempre que calgui una alternativa a les comunicacions via satèl•lit: vaixells a alta mar, avions fora de cobertura de xarxes ràdio amb visió directa, operacions militars, zones on la infraestructura ha estat destruïda per algun tipus de desastre o bé zones llunyanes sense cap altre tipus de comunicació. La ràdio HF representa una alternativa, o un sistema de backup al satèl•lit per a comunicacions de llarg abast i en redueix els costos, evita la vulnerabilitat i els problemes de sobirania.
En aquesta tesi s’ha estudiat l’enllaç HF entre la base antàrtica espanyola Juan Carlos I, situada a l’illa Livingston a l’arxipèlag de les Shetland del Sud, i Espanya. L’objectiu d’aquest treball és estudiar els problemes que afecten la propagació; és a dir, la relació senyal a soroll i interferència, la dispersió multicamí i la dispersió per efecte Doppler, i dissenyar la capa física d’un enllaç HF de baixa velocitat, poca potència i llarg abast. Pel que fa aquest últim punt es fan un parell de propostes: espectre eixamplat per seqüència directa (DSSS, en anglès) i multiplexació per divisió en freqüència ortogonal (OFDM, en anglès). El repte que es planteja és el de la definició de les característiques dels símbols que millor encaixen en aquest canal per tal d’obtenir un benefici de la diversitat temporal i freqüencial que ofereix el canal.
Des de l’any 2003 diverses campanyes han permès estudiar aquest canal HF, però no va ser fins la campanya 2009/2010 que s’obtingué un foto de les característiques, diürnes i nocturnes, de la ionosfera. En els articles que es presenten en aquesta tesi hem estès el rang freqüencial d’estudi respecte a investigacions prèvies i hem mostrat diferències de comportament entre el dia i la nit. Hem usat els resultats de la caracterització del canal per a dissenyar i comparar la bondat dels símbols DSSS i OFDM. Ambdues possibilitats han resultat ser candidates a implementar l’enllaç HF entre l’Antàrtida i Espanya. Tot i així, ambdues tècniques representen visions diferents de la implementació del mòdem: mentre que DSSS obté bons resultats a baixa velocitat en entorns amb baixa relació senyal a soroll, OFDM aconsegueix tasses de velocitat més elevades en canals més benignes.<br>Los sistemas de radio de alta frecuencia (HF, en inglés) son usados por agencias gubernamentales y no gubernamentales en todo el mundo siempre que se necesite una alternativa a las comunicaciones por satélite: barcos en alta mar, aviones fuera del rango de cobertura de las redes radio de visión directa, operaciones militares, zonas donde la infraestructura ha sido destruida por algún desastre. Ésta ofrece una alternativa, o representa un sistema de backup, a las comunicaciones vía satélite, evitando los costes, la vulnerabilidad y los problemas de soberanía de las comunicaciones por satélite.
En esta tesis se ha estudiado el enlace HF entre la base antártica española Juan Carlos I en la isla Livingston, en las Shetland del sur y España. El objetivo de este trabajo es el estudio de las limitaciones de la propagación ionosférica (como la relación señal a ruido e interferencia, la dispersión multicamino y la dispersión por efecto Doppler) y el diseño de la capa física de un enlace HF de baja velocidad, baja potencia y largo alcance. Se han estudiado un par de propuestas para este enlace, como son el espectro ensanchado por secuencia directa (DSSS, en inglés) y la multiplexación por división en frecuencia ortogonal (OFDM, en inglés). El reto ha sido definir las características que mejor se adecuan a este enlace para poder aprovechar la diversidad temporal y frecuencial que ofrece el canal HF.
Desde el año 2003 diversas campañas de sondeo han permitido estudiar el canal HF pero no es hasta la campaña 2009/2010 que se consigue una fotografía de la actividad ionosférica tanto nocturna como diurna. En los artículos que se presentan en esta tesis hemos extendido los estudios previos a todo el rango de frecuencias HF y hemos mostrado las diferencias entre el día y la noche. Hemos usado estos resultados de caracterización del canal para diseñar y comparar símbolos DSSS y símbolos OFDM. Ambas posibilidades han resultado ser posibles candidatas para implementar un enlace HF de baja velocidad entre la Antártida y España. Sin embargo ambas técnicas representan dos aproximaciones distintas a la implementación del módem. Mientras que DSSS consigue un buen funcionamiento a baja velocidad en escenarios con baja relación señal a ruido, OFDM consigue tasas de transmisión más altas en escenarios más benignos.<br>High Frequency (HF) radio is used by governmental and non nongovernmental agencies worldwide whenever an alternative to satellites for sky wave communication is needed: ships at sea, aircraft out of range of line-of-sight radio networks, military operations, disaster areas with communication infrastructure destroyed or distant regions lacking other communications. It offers an alternative to satellites, or a backup, for long-haul communications, thus avoiding the costs, vulnerabilities and sovereignty concerns of satellite communications.
In this thesis the HF link between the Antarctic Spanish Station Juan Carlos I in Livingston Island, South Shetlands and Spain is studied. The aim of this study is to address the impairments that affect HF propagation (i.e., signal-to-noise plus interference ratio, multipath and Doppler shift and spread) and to design the physical layer of a low rate, low power and long-haul HF link. Some proposals regarding this last issue are addressed, i.e., direct sequence spread spectrum (DSSS) and orthogonal frequency division multiplexing (OFDM). The challenge is to define the symbol characteristics that best fit the link to benefit from time and frequency diversity that offers the HF channel.
Since 2003 several transmission campaigns have allowed to study the HF channel but it is not until the 2009/2010 campaign that we have achieved a whole picture of both diurnal and nocturnal ionospheric activity. In the papers presented in this thesis we have extended the previous research to the whole range of HF frequencies and we have shown the differences on performance between day and night. We have used the results from channel characterization to design and compare the performance of DSSS and OFDM symbols. Both techniques have turned out to be possible candidates to implement a low rate HF link between Antarctica and Spain. However, both techniques stand for different approaches of the modem: DSSS achieves good performance at low data rate in low SNR scenarios, whereas OFDM achieves higher data rate in benign channels
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Elvidge, Sean. "On the use of multi-model ensemble techniques for ionospheric and thermospheric characterisation." Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/5526/.
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Space weather can have a negative impact on a number of radio frequency (RF) systems, with mitigation by ionospheric and thermospheric modelling one approach to improving system performance. However, before a model can be adopted operationally its performance must be quantified. Taylor diagrams, which show a model’s standard deviation and correlation, have been extended to further illustrate the model’s bias, standard deviation of error and mean square error in comparison to observational data. By normalising the statistics, multiple parameters can be shown simultaneously for a number of models. Using these modified Taylor diagrams, the first known long term (one month) comparison of three model types – empirical, physics and data assimilation - has been performed. The data assimilation models performed best, offering a statistically significant improvement in performance. One physics model performed sufficiently well that it is a viable background model option in future data assimilation schemes. Finally, multi-model thermospheric ensembles (MMEs) have been constructed from which the thermospheric forecasts exhibited a reduced root mean square error compared to non-ensemble approaches. Using an equally weighted MME the reduction was 55% and using a mean square error weighted approach the reduction was 48%.
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Kindervatter, Tim. "Survey of Ionospheric Propagation Effects and Modeling Techniques for Mitigation of GPS Error." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1515106508878179.
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Mahmoudian, Alireza. "New-Measurement Techniques to Diagnose Charged Dust and Plasma Layers in the Near-Earth Space Environment Using Ground-Based Ionospheric Heating Facilities." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/19239.
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Recently, experimental observations have shown that radar echoes from the irregularity<br />source region associated with mesospheric dusty space plasmas may be modulated by radio wave heating with ground-based ionospheric heating facilities. These experiments show great promise as a diagnostic for the associated dusty plasma in the Near-Earth Space Environment which is believed to have links to global change. This provides an alternative to more complicated and costly space-based observational approaches to investigating these layers. This dissertation seeks to develop new analytical and computational models to investigate fundamental physics of the associated dusty plasmas as well as utilize experimental observations during High Frequency HF ground-based heating experiments to develop practical techniques for diagnosing these dusty plasma layers.<br />The dependency of the backscattered signal strength (i.e. Polar Mesospheric Summer Echoes PMSEs) after the turn-on and turn-off of the radio wave heating on the radar frequency is an unique phenomenon that can shed light on the unresolved issues associated with the basic physics of the natural charged mesospheric dust layer. The physical process after turn-on and turn-off of radio wave heating is explained by competing ambipolar diffusion and dust charging processes. The threshold radar frequency and dust parameters for the enhancement or suppression of radar echoes after radio wave heating turn-on are investigated for measured mesospheric plasma parameters. The effect of parameters such as the electron temperature enhancement during radiowave heating, dust density, dust charge polarity, ion-neutral collision frequency, electron density and dust radius<br />on the temporal evolution of electron irregularities associated with PMSE is investigated.<br />The possibility of observing the turn-on overshoot (enhancement of radar echoes after the<br />radiowave turn-on) in the high frequency HF radar band is discussed based on typical mesospheric<br />parameters. It has been shown that predicted enhancement of electron irregularity<br />amplitude after heater turn-on at HF band is the direct manifestation of the dust charging<br />process in the space. Therefore further active experiments of PMSEs should be pursued<br />at HF band to illuminate the fundamental charging physics in the space environment to<br />provide more insight on this unique medium. Preliminary observation results of HF PMSE<br />heating experiment with the new 7.9 MHz radar at the European Incoherent Scatter EISCAT<br />facility appear promising for the existence of PMSE turn-on overshoot. Therefore, future<br />experimental campaigns are planned to validate these predictions.<br />Computational results are used to make predictions for PMSE active modification experiments at 7.9, 56, 139, 224 and 930MHz corresponding to existing ionospheric heating facilities. Data from a 2009 very high frequency VHF (224 MHz) experiment at EISCAT<br />is compared with the computational model to obtain dust parameters in the PMSE. The<br />estimated dust parameters as a result of these comparison show very reasonable agreement to dust radius and density at PMSE altitudes measured during a recent rocket experiment providing validation to the computational model.<br /><br />The first comprehensive analytical model for the temporal evolution of PMSE after heater<br />turn-on is developed and compared to a more accurate computational model as a reference.<br />It is shown that active PMSE heating experiments involving multiple observing frequencies<br />at 7.9 (HF), 56, and 224 MHz (VHF) may contribute further diagnostic capabilities since<br />the temporal evolution of radar echoes is substantially different for these frequency ranges.<br />It is shown that conducting PMSE active experiments at HF and VHF band simultaneously<br />may allow estimation of the dust density altitude profile, dust charge state variation during<br />the heating cycle, and ratio of electron temperature enhancement in the irregularity source<br />region. These theoretical and computational models are extended to study basic physics of the evolution of relevant dusty plasma instabilities thought to play an important role in irregularity production in mesospheric dust layers. A key focus is the boundary layer of these charged dust clouds. Several aspects of the cloud\'s structure (thickness of boundary layer, average particle size and density, collisional processes, and cloud expansion speed) and the ambient plasma are varied to determine the effect of these quantities on the resulting irregularities.<br />It was shown that for high collision frequencies, the waves may be very weakly excited (or<br />even quenched) and confined to the boundary layer. The excited dust acoustic waves inside<br />the dust cloud with frequency range of 7-15Hz and in the presence of electron bite-outs is<br />consistent with measured low frequency waves near 10 Hz by sounding rocket experiments<br />over the past decade. The observed radar echoes associated with the artificially created dust<br />clouds at higher altitudes in the ionosphere including space shuttle exhaust and upcoming<br />active space experiments in which localized dust layers will be created by sounding rockets<br />could be related to the excited acoustic waves predicted.<br />Finally, variation of spatial structures of plasma and dust (ice) irregularities in the PMSE<br />source region in the presence of positively charged dust particles is investigated. The correlation and anti-correlation of fluctuations in the electron and ion densities in the background plasma are studied considering the presence of positive dust particle formation. Recent rocket payloads have studied the properties of aerosol particles within the ambient plasma environment in the polar mesopause region and measured the signature of the positively charged particles with number densities of (2000 cm"3) for particles of 0.5-1 nm in radius.<br />The measurement of significant numbers of positively charged aerosol particles is unexpected from the standard theory of aerosol charging in plasma. Nucleation on the cluster ions is one of the most probable hypotheses for the positive charge on the smallest particles. The utility being that it may provide a test for determining the presence of positive dust particles.<br />The results of the model described show good agreement with observed rocket data. As an<br />application, the model is also applied to investigate the electron irregularity behavior during<br />radiowave heating assuming the presence of positive dust particles. It is shown that the<br />positive dust produces important changes in the behavior during Polar Mesospheric Summer Echo PMSE heating experiments that can be described by the fluctuation correlation and anti-correlation properties.<br />The second part of this dissertation is dedicated to Stimulated Electromagnetic Emissions SEEs produced by interaction of high power electromagnetic waves in the ionosphere. Nearearth ionospheric plasma presets a neutral laboratory for investigation of nonlinear wave phenomena in plasma which can not be studied in the laboratory environment due to the effect of physical boundary conditions. This process has been of great interest due to the<br />important diagnostic possibilities involving ability to determine mass of constitutive ions in<br />the interaction region through measurements of various gyro-frequencies. Objectives include<br />the consideration of the variation of the spectral behavior under pump power, proximity to<br />the gyro-harmonic frequency, and beam angle. Also, the relationship between such spectral<br />features and electron acceleration and creation of plasma irregularities was an important<br />focus.<br />Secondary electromagnetic waves excited by high power electromagnetic waves transmitted<br />into the ionosphere, commonly know as Stimulated Electromagnetic Emissions SEEs,<br />produced through Magnetized Stimulated Brillouin Scatter MSBS are investigated. Data<br />from two recent research campaigns at the High Frequency Active Auroral Research Program<br />facility HAARP is presented in this work. These experiments have provided additional<br />quantitative interpretation of the SEE spectrum produced by MSBS to yield diagnostic measurements of the electron temperature in the heated ionosphere. SEE spectral emission lines corresponding to ion acoustic IA and electrostatic ion cyclotron EIC modes were observed with a shift in frequency up to a few tens of Hz from radio waves transmitted near the third harmonic of the electron gyro-frequency 3fce. The threshold of each emission line has been measured by changing the pump wave amplitude. The experimental results aimed to show the threshold for transmitter power to excite IA waves propagating along the magnetic field lines as well as for EIC waves excited at oblique angles relative to the background magnetic field. A full wave solution has been used to estimate the amplitude of the electric field at the interaction altitude. The estimated growth rate using the theoretical model is compared with the threshold of MSBS lines in the experiment and possible diagnostic information for the background ionospheric plasmas is discussed. Simultaneous formation of artificial field aligned irregularities FAIs and suppression of the MSBS process is investigated. Recently, there has been significant interest in ion gyro-harmonic structuring the Stimulated Electromagnetic Emission SEE spectrum due to the potential for new diagnostic information available about the heated volume and ancillary processes such as creation of artificial ionization layers. These relatively recently discovered emission lines have almost exclusively been studied for second electron gyro-harmonic heating. The first extensive systematic investigations of the possibility of these spectral features for third electron gyro-harmonic heating are provided here. Discrete spectral features shifted from the transmit frequency ordered by harmonics of the ion gyro-frequency were observed for third electron gyro-harmonic heating for the first time at a recent campaign at a High Frequency Active Auroral Research Program Facility HAARP. These features were also closely correlated with a broader band feature at a larger frequency shift from the transmit frequency known as the Downshifted Peak DP. The power threshold of these spectral features was measured, as well as their behavior with heater<br />beam angle, and proximity of the transmit frequency to the third electron gyro-harmonic frequency. Comparisons were also made with similar spectral features observed during 2nd<br />electron gyro-harmonic heating during the same campaign. A theoretical model is provided<br />that interprets these spectral features as resulting from parametric decay instabilities in<br />which the pump field ultimately decays into high frequency upper hybrid/electron Bernstein<br />and low frequency neutralized ion Bernstein IB and/or obliquely propagating ion acoustic<br />waves at the upper hybrid interaction altitude. Coordinated optical and SEE observations<br />were carried out in order to provide a better understanding of electron acceleration and precipitation<br />processes. Optical emissions were observed associated with SEE gyro-harmonic<br />features for pump heating near the second electron gyro-harmonic during the campaign. The<br />observations affirm strong correlation between the gyro-structures and the airglow.<br>Ph. D.
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Oronsaye, Samuel Iyen Jeffrey. "Updating the ionospheric propagation factor, M(3000)F2, global model using the neural network technique and relevant geophysical input parameters." Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1001609.
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This thesis presents an update to the ionospheric propagation factor, M(3000)F2, global empirical model developed by Oyeyemi et al. (2007) (NNO). An additional aim of this research was to produce the updated model in a form that could be used within the International Reference Ionosphere (IRI) global model without adding to the complexity of the IRI. M(3000)F2 is the highest frequency at which a radio signal can be received over a distance of 3000 km after reflection in the ionosphere. The study employed the artificial neural network (ANN) technique using relevant geophysical input parameters which are known to influence the M(3000)F2 parameter. Ionosonde data from 135 ionospheric stations globally, including a number of equatorial stations, were available for this work. M(3000)F2 hourly values from 1976 to 2008, spanning all periods of low and high solar activity were used for model development and verification. A preliminary investigation was first carried out using a relatively small dataset to determine the appropriate input parameters for global M(3000)F2 parameter modelling. Inputs representing diurnal variation, seasonal variation, solar variation, modified dip latitude, longitude and latitude were found to be the optimum parameters for modelling the diurnal and seasonal variations of the M(3000)F2 parameter both on a temporal and spatial basis. The outcome of the preliminary study was applied to the overall dataset to develop a comprehensive ANN M(3000)F2 model which displays a remarkable improvement over the NNO model as well as the IRI version. The model shows 7.11% and 3.85% improvement over the NNO model as well as 13.04% and 10.05% over the IRI M(3000)F2 model, around high and low solar activity periods respectively. A comparison of the diurnal structure of the ANN and the IRI predicted values reveal that the ANN model is more effective in representing the diurnal structure of the M(3000)F2 values than the IRI M(3000)F2 model. The capability of the ANN model in reproducing the seasonal variation pattern of the M(3000)F2 values at 00h00UT, 06h00UT, 12h00UT, and l8h00UT more appropriately than the IRI version is illustrated in this work. A significant result obtained in this study is the ability of the ANN model in improving the post-sunset predicted values of the M(3000)F2 parameter which is known to be problematic to the IRI M(3000)F2 model in the low-latitude and the equatorial regions. The final M(3000)F2 model provides for an improved equatorial prediction and a simplified input space that allows for easy incorporation into the IRI model.
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Damtie, B. (Baylie). "New incoherent scatter radar measurement techniques and data analysis methods." Doctoral thesis, Oulun yliopisto, 2004. http://urn.fi/urn:isbn:9514273125.
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Abstract This dissertation presents new incoherent scatter radar measurement techniques and data analysis methods. The measurements used in the study were collected by connecting a computer-based receiver to the EISCAT (European Incoherent SCATter) radar on Svalbard. This hardware consists of a spectrum analyzer, a PCI-bus-based programmable digital I/O card and a desktop computer with a large-capacity hard disk. It takes in the 70-MHz signal from the ESR (Eiscat Svalbard Radar) signal path and carries out down-conversion, AD conversion, quadrature detection, and finally stores the output samples effective sampling rate is 1 MHz, large enough to span all the frequency channels used in the experiment. Hence the total multichannel signal was stored instead of separate lagged products for each frequency channel, which is the procedure in the standard hardware. This solution has some benefits including elimination of ground clutter with only a small loss in statistical accuracy. The capability of our hardware in storing the incoherent scatter radar signals directly allows us to use very flexible and versatile signal processing methods, which include clutter suppression, filtering, decoding, lag prole calculation, inversion and optimal height integration. The performance of these incoherent scatter radar measurement techniques and data analysis methods are demonstrated by employing an incoherent scatter experiment that applies a new binary phase code. Each bit of this code has been further coded by a 5-bit Barker code. In the analysis, stochastic inversion has been used for the first time in decoding Barker-coded incoherent scatter measurements, and this method takes care of the ambiguity problems associated with the measurements. Finally, we present new binary phase codes with corresponding sidelobe-free decoding filters that maximize the signal-to-noise ratio (SNR) and at the same time eliminate unwanted sidelobes completely<br>Original papers The original papers are not included in the electronic version of the dissertation. Lehtinen, M., Markkanen, J., Väänänen, A., Huuskonen, A., Damtie, B., Nygrén, T., & Rahkola, J. (2002). A new incoherent scatter technique in the EISCAT Svalbard Radar. Radio Science, 37(4), 3-1-3–14. https://doi.org/10.1029/2001rs002518 Damtie, B., Nygrén, T., Lehtinen, M. S., & Huuskonen, A. (2002). High resolution observations of sporadic-E layers within the polar cap ionosphere using a new incoherent scatter radar experiment. Annales Geophysicae, 20(9), 1429–1438. https://doi.org/10.5194/angeo-20-1429-2002 Damtie, B., Lehtinen, M. S., & Nygrén, T. (2004). Decoding of Barker-coded incoherent scatter measurements by means of mathematical inversion. Annales Geophysicae, 22(1), 3–13. https://doi.org/10.5194/angeo-22-3-2004 Lehtinen, M. S., Damtie, B., & Nygrén, T. (2004). Optimal binary phase codes and sidelobe-free decoding filters with application to incoherent scatter radar. Annales Geophysicae, 22(5), 1623–1632. https://doi.org/10.5194/angeo-22-1623-2004
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Cruz, Edith Liliana Macotela. "Contribuição ao estudo de distúrbios ionosféricos utilizando a técnica de VLF." Universidade Presbiteriana Mackenzie, 2015. http://tede.mackenzie.br/jspui/handle/tede/1301.
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Previous issue date: 2015-03-09<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico<br>The Earth-Low ionosphere system behaves as a waveguide for the propagation of radio waves of very low frequency (VLF). If in this system the electrical conductivity of its boundaries is perturbed, the propagation of the VLF waves will also be perturbed. There is a diversity of transient physical phenomena that are able to alter significantly the electrical conductivity of the lower ionosphere. The disturbance in this region is able to produce phase and amplitude variations with respect to a quiescent level of these waves. The aim of the present work is to study the response of the lower ionosphere to phenomena originated in the Earth, our solar system or even much farther away. For this purpose, VLF data obtained by SAVNET (South American VLF Network) during the solar cycle 24 was used. It was found that the correction by both the length of the path illuminated by the flare and the reference height coefficient allows normalizing the effect of ionospheric disturbances observed in the VLF phase signals that propagated along trajectories with a north-south or west-east direction, separately. The lower limit of detection for disturbances caused by the X-ray radiation excess is 1.8×10−9 Jm-2 and 2.6×10−7 Jm-2 for the nighttime and daytime lower ionosphere, respectively. Changes in the periodicities of the VLF signal, in the infrasonic band, were observed between 6 and 14 days prior to the seismic events, of magnitude 7, occurred in Haiti in 2010 and in Peru in 2011. Increases in the periodicities of the order of few minutes were observed when the shadow of the total solar eclipse of 2010 was moving on the Earth. Due to the solar eclipse the ionospheric reference height increased in ~3 km and the electron density decreased in 60 % of its quiescent level. Finally, it was found that the effective recombination coefficient, for 80 km height, was 1.1×10−5 cm-3s-1 during the time of the eclipse, which is an intermediate value between the diurnal and nocturnal conditions.<br>O sistema Terra-baixa ionosfera se comporta como um guia de onda para a propagação de ondas de rádio de frequências muito baixa (VLF). Se neste sistema a condutividade elétrica das fronteiras é perturbada, a propagação da onda é também perturbada. Existe uma variedade de fenômenos físicos transientes que alteram significativamente a condutividade elétrica da baixa ionosfera. Essas alterações são observadas como variações da fase e/ou amplitude com respeito ao nível quiescente. O presente trabalho tem como finalidade estudar a resposta da baixa ionosfera a fenômenos que produzidos na Terra, no sistema solar e até aqueles produzidos muito além do sistema solar. Com esse fim foram utilizados dados de VLF de fase e de amplitude fornecidos pela rede SAVNET (South America VLF NETwork) para o ciclo solar 24. Foi encontrado que a correção pelo fator de distância iluminada e o coeficiente de altura de referência permitem normalizar o efeito do distúrbio ionosférico a partir do sinal de VLF propagado em trajetos com direção de propagação norte-sul ou oeste-leste. O limiar de detecção das perturbações causadas pelo excesso na incidência dos raios-X é 1,8×10−9 Jm-2 para a ionosfera noturna e 2,6×10−7 Jm-2 para a ionosfera diurna. Perturbações ionosféricas observadas como alterações nos períodos do sinal de VLF, na faixa de infrassom, foram observadas entre 6 e 14 dias antes dos eventos sísmicos de magnitude 7 acontecidos no Haiti no ano 2010 e no Peru no ano 2011. Alterações nas periodicidades, da ordem de dezenas de minutos, foram observadas quando a sombra do eclipse solar total de 2010 se deslocava sobre a Terra. Devido ao eclipse, a altura de referência da ionosfera aumentou em ~3 km e a densidade eletrônica diminuiu em 60% com respeito do nível quiescente. Finalmente, foi encontrado que o coeficiente de recombinação efetiva, para o tempo do eclipse e para uma altura de 80 km, foi de 1,1×10−5 cm-3s-1, que é um valor intermediário entre as condições diurnas e noturnas.
Books on the topic "Ionospheric techniques"
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G, Laneve, Herrero F. A, and European Geophysical Society, eds. Space techniques for acquisition of aeronomic-ionospheric data in the lower thermosphere. Pergamon, 2001.
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United States. National Aeronautics and Space Administration., ed. Investigation of radio wave propagation in the Martian ionosphere utilizing HF sounding techniques: Thesis ... National Aeronautics and Space Administration, 1996.
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Institution, of Engineering and Technology International Conference on Ionospheric Radio Systems and Techniques (10th 2006 London England). The 10th Institution of Engineering and Technology International Conference on Ionospheric Radio Systems and Techniques: (IRST2006) : 18 -21 July 2006. The Royal Society of Medicine, 2006.
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Hunsucker, Robert D. Radio Techniques for Probing the Terrestrial Ionosphere. Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-76257-4.
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Hunsucker, Robert D. Radio Techniques for Probing the Terrestrial Ionosphere. Springer Berlin Heidelberg, 1991.
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1931-, Liu C. H., World Ionosphere/Thermosphere Study (Organization), International Council of Scientific Unions. Scientific Committee on Solar-Terrestrial Physics, and National Science Foundation (U.S.), eds. WITS handbook. National Science Foundation], 1990.
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URSI/IAU Symposium on Radio Astronomical Seeing (1989 Beijing, China). Proceedings of URSI/IAU Symposium on Radio astronomical seeing, 15-19 May 1989, Beijing, China. Edited by Baldwin J. E, Wang Shouguan, and International Union of Radio Science. International Academic Publishers, 1990.
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United States. National Aeronautics and Space Administration., ed. Global auroral imaging for the Dynamics Explorer mission: NAG5-483 : summary of research, November 01, 1984-January 31, 1998. Dept. of Physics and Astronomy, University of Iowa, 1998.
Find full textBook chapters on the topic "Ionospheric techniques"
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Hunsucker, Robert D. "Ionospheric Modification by High Power Radio Waves." In Radio Techniques for Probing the Terrestrial Ionosphere. Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-76257-4_6.
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Rodriguez, P., C. L. Siefring, D. G. Haas, M. M. Baumback, and D. P. McNutt. "In Situ Detection of Ionospheric Cavitons: Experimental Considerations." In Measurement Techniques in Space Plasmas: Particles. American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm102p0073.
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Holzworth, R. H., and E. A. Bering. "Ionospheric electric fields from stratospheric balloon-borne probes." In Measurement Techniques in Space Plasmas: Fields. American Geophysical Union, 1998. http://dx.doi.org/10.1029/gm103p0079.
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Gilchrist, B. E., R. A. Heelis, and W. J. Raitt. "Ionospheric multi-point measurements using tethered satellite sensors." In Measurement Techniques in Space Plasmas: Fields. American Geophysical Union, 1998. http://dx.doi.org/10.1029/gm103p0317.
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Fenrich, F. R., C. L. Waters, M. Connors, and C. Bredeson. "Ionospheric signatures of ULF waves: Passive radar techniques." In Magnetospheric ULF Waves: Synthesis and New Directions. American Geophysical Union, 2006. http://dx.doi.org/10.1029/169gm17.
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Yeoman, T. K., D. M. Wright, and L. J. Baddeley. "Ionospheric signatures of ULF waves: Active radar techniques." In Magnetospheric ULF Waves: Synthesis and New Directions. American Geophysical Union, 2006. http://dx.doi.org/10.1029/169gm18.
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Pollock, C. J., V. N. Coffey, J. D. England, N. G. Martinez, T. E. Moore, and M. L. Adrian. "Thermal Electron Capped Hemisphere Spectrometer (TECHS) for Ionospheric Studies." In Measurement Techniques in Space Plasmas: Particles. American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm102p0201.
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Fiori, Robyn A. D. "Spherical Cap Harmonic Analysis Techniques for Mapping High-Latitude Ionospheric Plasma Flow—Application to the Swarm Satellite Mission." In Ionospheric Multi-Spacecraft Analysis Tools. Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-26732-2_9.
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García-Fernández, Miquel, Manuel Hernandez-Pajares, Jose Miguel Juan-Zornoza, and Jaume Sanz-Subirana. "An Improvement of Retrieval Techniques for Ionospheric Radio Occultations." In First CHAMP Mission Results for Gravity, Magnetic and Atmospheric Studies. Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-540-38366-6_59.
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Finlay, Christopher C. "Models of the Main Geomagnetic Field Based on Multi-satellite Magnetic Data and Gradients—Techniques and Latest Results from the Swarm Mission." In Ionospheric Multi-Spacecraft Analysis Tools. Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-26732-2_12.
Full textConference papers on the topic "Ionospheric techniques"
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Chatellier, C. "Image coding and ionospheric link." In 8th International Conference on High-Frequency Radio Systems and Techniques. IEE, 2000. http://dx.doi.org/10.1049/cp:20000139.
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Underhill, M. J. "A comparison of methods for the measurement of ionospheric tilt from a topside ionospheric sounder." In 8th International Conference on High-Frequency Radio Systems and Techniques. IEE, 2000. http://dx.doi.org/10.1049/cp:20000180.
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Kunitsyn, V. E., E. D. Tereshchenko, E. S. Andreeva, I. A. Nesterov, and M. O. Nazarenko. "Ionospheric mapping and radio tomography." In IET 11th International Conference on Ionospheric Radio Systems and Techniques (IRST 2009). IEE, 2009. http://dx.doi.org/10.1049/cp.2009.0027.
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Zakharenkova, I. E., and I. I. Shagimuratov. "Using of global and regional ionospheric maps to study of the preseismic ionosphere modification." In IET 11th International Conference on Ionospheric Radio Systems and Techniques (IRST 2009). IEE, 2009. http://dx.doi.org/10.1049/cp.2009.0025.
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Vastberg, A. "RaTS, a system for ionospheric ray tracing." In Sixth International Conference on `HF Radio Systems and Techniques'. IEE, 1994. http://dx.doi.org/10.1049/cp:19940525.
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Sanz-Gonzalez, J. L., S. Zazo-Bello, I. A. Perez-Alvarez, and J. Lopez-Perez. "Parameter estimation algorithms for ionospheric channels." In IET 11th International Conference on Ionospheric Radio Systems and Techniques (IRST 2009). IEE, 2009. http://dx.doi.org/10.1049/cp.2009.0023.
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Ndao, P. M., D. Lemur, Y. Erhel, and C. Brousseau. "Capacity estimation of MIMO ionospheric channels." In IET 11th International Conference on Ionospheric Radio Systems and Techniques (IRST 2009). IEE, 2009. http://dx.doi.org/10.1049/cp.2009.0032.
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Jackson-Booth, N. K., P. S. Cannon, M. Bradley, and P. A. Arthur. "New oblique sounders for ionospheric research." In 12th IET International Conference on Ionospheric Radio Systems and Techniques (IRST 2012). IET, 2012. http://dx.doi.org/10.1049/cp.2012.0363.
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Milsom, J. D. "The evolution of an ionospheric forecasting service." In 8th International Conference on High-Frequency Radio Systems and Techniques. IEE, 2000. http://dx.doi.org/10.1049/cp:20000171.
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Bartlett, A. "A flexible, low-cost, ionospheric sounding system." In IEE Colloquium on Frequency Selection and Management Techniques for HF Communications. IEE, 1996. http://dx.doi.org/10.1049/ic:19960119.
Full textReports on the topic "Ionospheric techniques"
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Basu, Sunanda. Multi-Technique Studies of Ionospheric Plasma Structuring. Defense Technical Information Center, 2006. http://dx.doi.org/10.21236/ada612082.
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Basu, Sunanda. Multi-technique Studies of Ionospheric Plasma Structuring. Defense Technical Information Center, 2008. http://dx.doi.org/10.21236/ada533973.
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Basu, Sunanda. Multi-Technique Studies of Ionospheric Plasma Structuring. Defense Technical Information Center, 2007. http://dx.doi.org/10.21236/ada573400.
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Basu, Sunanda. Multi-technique Studies of Ionospheric Plasma Structuring. Defense Technical Information Center, 2009. http://dx.doi.org/10.21236/ada602953.
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Keskinen, Michael J. Development of Multiscale Ionosphere-thermosphere Forecasting Techniques and Models. Defense Technical Information Center, 1997. http://dx.doi.org/10.21236/ada629247.
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Reinisch, Bodo, and Gary Sales. Measuring Electrodynamics of the Ionosphere by Digital Ionosondes and Other Techniques. Defense Technical Information Center, 2000. http://dx.doi.org/10.21236/ada401996.
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Reinisch, Bodo, and Gary Sales. Measuring Electrodynamics of the Ionosphere by Digital Ionosondes and Other Techniques. Defense Technical Information Center, 2001. http://dx.doi.org/10.21236/ada402979.
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