Thesis (M.S. in Astronautical Engineering)--Naval Postgraduate School, December 2003. / "December 2003". Thesis advisor(s): Cristi, Roberto ; Agrawal, Brij. Includes bibliographical references (p. 53). Also available online.

Thesis (Ph. D.)--University of Texas at Austin, 2005. / Supervisor: Clark R. Wilson. Vita. Includes bibliographical references.

Thesis (M.S.)--Montana State University--Bozeman, 2004. / Typescript. Chairperson, Graduate Committee: Rick Lawrence. Includes bibliographical references (leaves 72-80).

Thesis (Ph. D.)--University of Texas at Austin, 2005. / Vita. Includes bibliographical references (leaves 126-130).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1984. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 132-153).

Thesis (M.S.)--University of Wisconsin. / eContent provider-neutral record in process. Description based on print version record. Bibliography: leaves 53-59.

Thesis (Ph. D.)--University of Missouri-Columbia, 2005. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (May 25, 2006) Vita. Includes bibliographical references.

Th.--Astrophys.--Toulouse 3, 1982. N°: 1045.

The growth of satellite communication industry and the need to offer new and better services, to compete with optical fiber systems, have driven the satellite industry to search for higher bandwidth and improved cost of services. Higher frequency bands, such as Ka and V-band, came into play. These frequency bands have the advantage of efficient use of spectrum, the ability to transfer data at much higher rates, and the use of smaller antennas resulting in lower cost for the user. A major drawback though, is the severity of propagation impairments. Scintillation becomes important for low-fade margin systems operating at high frequencies and with low elevation angles and therefore must be taken into account in the design of satellite communication systems. The first part of the thesis deals with the analysis of beacon data and presentation of various statistics, namely short and long-term distributions of scintillation amplitudes and intensity. Their correlations with meteorological parameters are also presented. A dynamic model of tropospheric scintillation is developed, which permits the generation of scintillation time series based on known scintillation characteristics, such as spectral shape and probability density function. The model employs readily obtainable input parameters (antenna diameter, path elevation angle, frequency, ground temperature and humidity) and yields statistics that compare extremely well with existing prediction models as well as measured scintillation data (up to the fourth moment). Important applications of the new model are for simulating the performance of scintillation-degraded communication links and predicting required scintillation fade margins. The second part of the thesis investigates the effects of scintillation on digital satellite communication systems using simulations implemented in COSSAP. Simulation results show that the higher the order of the modulation that is being used, the larger is the effect of scintillation on the bit error rate performance of the link. In the third part of the thesis, fade mitigation techniques to overcome the effects of scintillation fading are discussed. Analysis of an adaptive modulation system using three modulation techniques is presented and its advantages demonstrated. The adaptive system can be used to mitigate scintillation fading and at the same time increase the capacity of the system, decreasing system outage time through an efficient utilisation of available resources. In the last part, data transfer scenarios in VSAT systems incorporating adaptive modulation, ARQ and adaptive up-link power control are presented. The implementation of the adaptive system in a COSSAP simulation platform is discussed and individual adaptive components are simulated and presented in detail.

Made available in DSpace on 2014-06-11T19:25:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-10-01Bitstream added on 2014-06-13T19:12:16Z : No. of bitstreams: 1 capelo_m_me_guara.pdf: 9441304 bytes, checksum: 976fcacdfa9765f692caf8a068ecc84b (MD5) / Universidade Estadual Paulista (UNESP) / Devido ao grande avanço da tecnologia espacial o número de satélites irregulares conhecidos vem aumentando rapidamente nos últimos anos. O estudo das perturbações que agem sobre estes satélites contribui para explicar a origem e estabilidade da órbita destes corpos celestes. Uma dessas perturbações é a ressonância de evecção que se caracteriza por ser um fenômeno no qual o pericentro da órbita do satélite fica preso na direção do corpo perturbador. Outra perturbação no movimento desses satélites de altas inclinações se dá quando o argumento do pericentro circula ou libra em torno de 90º ou 270º, ou seja, a ressonância Kozai (Kozai 1962). Neste trabalho, é feito um estudo semi-analítico dos efeitos da ressonância de evecção no movimento orbital dos satélites irregulares do planeta Júpiter, utilizando a função perturbadora desenvolvida por Cuk et al. (2004) e que contém termos das ressonâncias de evecção e Kozai. O princípio da média é aplicado somente no movimento orbital do satélite. É feita uma extensa análise do comportamento dos elementos orbitais de uma partícula nas regiões habitadas pelos satélites irregulares. / In the recent years, due to the great advance of the space technology, the number of known irregular satellites is increasing quickly. Studying the disturbances which act on these satellites may contribute to explain the origin and stability of the orbit of these satellites. One of the main disturbances is the evection resonance which is characterized by fixing the pericenter of the orbit of the satellite in the direction of the disturbing body. Another disturbance, know as Kozai resonance (Kozai 1962), acts in the movement of those satellites with high inclinations and makes the argument of pericentro circulates or librates around 90º or 270º. In this work is made a semianalytical study of the evection resonance effect in the orbital movement of the irregular satellites of the Jupiter planet. It is used the disturbing function developed by Cuk et al. (2004) which contain terms of evection and Kozai resonances. The principle of the average is only applied in the orbital movement of the satellite. It is made an extensive analysis of the behavior of the orbital elements of a particle in the regions inhabited for the irregular satellites.