Ionospheric Scintillation Effects on VHF-UHF Communication Systems PDF Download
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Author: H. E. Whitney
Publisher:
ISBN:
Category : Artificial satellites
Languages : en
Pages : 28
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Book Description
Author: H. E. Whitney
Publisher:
ISBN:
Category : Artificial satellites
Languages : en
Pages : 28
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Book Description
Author: Jules Aarons
Publisher:
ISBN:
Category : F region
Languages : en
Pages : 30
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Book Description
Updating a review of the global morphology of ionospheric scintillations published in 1971, this study adds additional experimental studies on familiar topics to newer types of measurements of ionospheric irregularities, including in situ experiments and artificial heating of the F-layer.
Author: Sunanda Basu
Publisher:
ISBN:
Category : Auroras
Languages : en
Pages : 136
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Book Description
Aerosol models have been developed for the lower atmosphere. These models are representative of conditions found in rural, urban, and maritime air masses. The changes in the aerosol properties with variations in the relative humidity are discussed. To describe the aerosol optical properties in the extreme of 100 percent relative humidity, several fog models are presented. For each model the coefficients for extinction, scattering, and absorption, the angular scattering distribution, and other optical parameters have been computed for wavelengths between 0.2 and 40 microns. These aerosol models are presented together with a review of their experimental basis. The optical properties of these models are discussed and some comparisons of the model with experimental measurements are presented.
Author: Chao Huang
Publisher: John Wiley & Sons
ISBN: 1119507553
Category : Science
Languages : en
Pages : 47
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Book Description
A comprehensive review of global ionospheric research from the polar caps to equatorial regions It's more than a century since scientists first identified the ionosphere, the layer of the Earth’s upper atmosphere that is ionized by solar and cosmic radiation. Our understanding of this dynamic part of the near-Earth space environment has greatly advanced in recent years thanks to new observational technologies, improved numerical models, and powerful computing capabilities. Ionosphere Dynamics and Applications provides a comprehensive overview of historic developments, recent advances, and future directions in ionospheric research. Volume highlights include: Behavior of the ionosphere in different regions from the poles to the equator Distinct characteristics of the high-, mid-, and low-latitude ionosphere Observational results from ground- and space-based instruments Ionospheric impacts on radio signals and satellite operations How earthquakes and tsunamis on Earth cause disturbances in the ionosphere The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals. Find out more about the Space Physics and Aeronomy collection in this Q&A with the Editors in Chief
Author: Joseph Horace Pope
Publisher:
ISBN:
Category : Magnetic storms
Languages : en
Pages : 44
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Book Description
A global model for obtaining scintillations was developed at Stanford Research Institute by Fremouw. This model uses a number of input parameters including sunspot number, day of the year, time of day, location of the receiver and transmitter, the frequency to provide an average value of scintillation activity under the specified conditions. The model was later modified by Pope at NOAA/ERL to better represent certain measurements of scintillation activity in the high latitude regions and to include a variation in the magnetic activity index. The model uses the Briggs and Parkin theory appropriate for weak scatter. Certain convenient mathematical forms are assumed for the different regions of the earth. These include the equatorial, mid-latitude, auroral zone, and high latitude boundary regions. The coefficients in these mathematical functions were determined empirically by means of appropriate scintillation activity data that were taken in many different regions of the globe and over different portions of the sunspot cycle. The model is valid only for that frequency domain (VHF, UHF) upon which the observational data were based. The model is described in this report with its uses and limitations. Details of a computer program based on the model that gives scintillation activity as a function of the various input parameters are also provided.
Author: Jules Aarons
Publisher:
ISBN:
Category : Geostationary satellites
Languages : en
Pages : 48
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Book Description
Amplitude fluctuations produced by small irregularities in electron density in the F-layer of the ionosphere (at 300 to 400 km height) can be a problem to communication and navigation systems in the VHF-UHF range. Recent measurements, primarily by AFCRL, are shown with emphasis on results at high and equatorial latitudes. At high latitudes an irregularity region exists whose lower boundary reaches 57 degrees invariant latitude near midnight. During magnetic storms the boundary descends to lower latitudes and the fading becomes deeper. Over the polar cap scintillations are somewhat diminished. When observing synchronous satellites through the irregularity region, deep and fast fading is frequently seen, with fade rates to one per second. Irregularities produce deep scintillations in the VHF range plus or minus 15 degrees from the geomagnetic equator. In equatorial regions maximum occurrence of high level scintillations takes place between 2100 and 2400 local time during the equinoxes; a minimum occurrence is observed during the solstices. When the sunspot number decreases, the equatorial irregularity region spreads and becomes larger. The data for various latitudes has been placed in statistical form, that is, distribution of amplitudes for 15-min samples as well as for periods of 1 yr and longer. (Author).
Author: Vladislav Demyanov
Publisher:
ISBN: 9781789853018
Category :
Languages : en
Pages :
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Book Description
"Being a vital modern technology, satellite systems for navigation, telecommunication, and geosciences have developed rapidly in the last 25 years. Modern satellite technologies have become a base of our civilization and support our day-to-day activity in both practice and geosciences. This book is devoted to GNSS-remote sensing for ionosphere research, modeling and mitigation techniques to diminish the ionosphere and multipath impacts on GNSS, and survey of the modern satellite missions and technologies. We hope that the experts' opinions presented in the book will be interesting for the research community and students in the area of satellites and space missions as well as in engineering and geoscience research" -- IntechOpen.
Author: Massimo Materassi
Publisher: Elsevier
ISBN: 0128147830
Category : Science
Languages : en
Pages : 340
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Book Description
The Dynamical Ionosphere: A Systems Approach to Ionospheric Irregularity examines the Earth's ionosphere as a dynamical system with signatures of complexity. The system is robust in its overall configuration, with smooth space-time patterns of daily, seasonal and Solar Cycle variability, but shows a hierarchy of interactions among its sub-systems, yielding apparent unpredictability, space-time irregularity, and turbulence. This interplay leads to the need for constructing realistic models of the average ionosphere, incorporating the increasing knowledge and predictability of high variability components, and for addressing the difficulty of dealing with the worst cases of ionospheric disturbances, all of which are addressed in this interdisciplinary book. Borrowing tools and techniques from classical and stochastic dynamics, information theory, signal processing, fluid dynamics and turbulence science, The Dynamical Ionosphere presents the state-of-the-art in dealing with irregularity, forecasting ionospheric threats, and theoretical interpretation of various ionospheric configurations. - Presents studies addressing Earth's ionosphere as a complex dynamical system, including irregularities and radio scintillation, ionospheric turbulence, nonlinear time series analysis, space-ionosphere connection, and space-time structures - Utilizes interdisciplinary tools and techniques, such as those associated with stochastic dynamics, information theory, signal processing, fluid dynamics and turbulence science - Offers new data-driven models for different ionospheric variability phenomena - Provides a synoptic view of the state-of-the-art and most updated theoretical interpretation, results and data analysis tools of the "worst case" behavior in ionospheric configurations
Author: H. E. Whitney
Publisher:
ISBN:
Category : Artificial satellites
Languages : en
Pages : 46
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Book Description
The fading characteristics of ionospheric scintillations can be precisely described by a cumulative amplitude probability distribution function (cdf). The cdf expresses the probability or percentage of time that the signal amplitude will equal or exceed a given amplitude. Utilizing ionospheric scintillations observed on beacon signals from synchronous satellites transmitting at 136 MHz, distributions of amplitude variations have been made. The resulting distributions have been divided into five groups corresponding to ranges of scintillation index, the predominant measure in scintillation studies. The five distribution models are then combined with the occurrence of scintillations in various index ranges to produce cumulative amplitude probability distributions. These have been done for long term observations made at Hamilton, Mass., Narssarssuaq, Greenland, and Huancayo, Peru. The resulting data allows engineers to determine margins necessary for communication and navigation systems. (Author).
Author: Y. Jade Morton
Publisher: John Wiley & Sons
ISBN: 1119458412
Category : Science
Languages : en
Pages : 1170
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Book Description
Covers the latest developments in PNT technologies, including integrated satellite navigation, sensor systems, and civil applications Featuring sixty-four chapters that are divided into six parts, this two-volume work provides comprehensive coverage of the state-of-the-art in satellite-based position, navigation, and timing (PNT) technologies and civilian applications. It also examines alternative navigation technologies based on other signals-of-opportunity and sensors and offers a comprehensive treatment on integrated PNT systems for consumer and commercial applications. Volume 1 of Position, Navigation, and Timing Technologies in the 21st Century: Integrated Satellite Navigation, Sensor Systems, and Civil Applications contains three parts and focuses on the satellite navigation systems, technologies, and engineering and scientific applications. It starts with a historical perspective of GPS development and other related PNT development. Current global and regional navigation satellite systems (GNSS and RNSS), their inter-operability, signal quality monitoring, satellite orbit and time synchronization, and ground- and satellite-based augmentation systems are examined. Recent progresses in satellite navigation receiver technologies and challenges for operations in multipath-rich urban environment, in handling spoofing and interference, and in ensuring PNT integrity are addressed. A section on satellite navigation for engineering and scientific applications finishes off the volume. Volume 2 of Position, Navigation, and Timing Technologies in the 21st Century: Integrated Satellite Navigation, Sensor Systems, and Civil Applications consists of three parts and addresses PNT using alternative signals and sensors and integrated PNT technologies for consumer and commercial applications. It looks at PNT using various radio signals-of-opportunity, atomic clock, optical, laser, magnetic field, celestial, MEMS and inertial sensors, as well as the concept of navigation from Low-Earth Orbiting (LEO) satellites. GNSS-INS integration, neuroscience of navigation, and animal navigation are also covered. The volume finishes off with a collection of work on contemporary PNT applications such as survey and mobile mapping, precision agriculture, wearable systems, automated driving, train control, commercial unmanned aircraft systems, aviation, and navigation in the unique Arctic environment. In addition, this text: Serves as a complete reference and handbook for professionals and students interested in the broad range of PNT subjects Includes chapters that focus on the latest developments in GNSS and other navigation sensors, techniques, and applications Illustrates interconnecting relationships between various types of technologies in order to assure more protected, tough, and accurate PNT Position, Navigation, and Timing Technologies in the 21st Century: Integrated Satellite Navigation, Sensor Systems, and Civil Applications will appeal to all industry professionals, researchers, and academics involved with the science, engineering, and applications of position, navigation, and timing technologies. pnt21book.com
