Título:	Análise e verificação empírica de modelos de predição de frequências para comunicação em HF em regiões de baixa latitude
Autor(es):	Marques, Antonio Anderson Silva
E-mail do autor:	silvamarques.anderson@eb.mil.br
Orientador(es):	Carvalho, Paulo Henrique Portela de
Assunto:	Espalhamento equatorial Alta frequência
Data de publicação:	6-mar-2021
Data de defesa:	19-out-2020
Referência:	MARQUES, Antonio Anderson Silva. Análise e verificação empírica de modelos de predição de frequências para comunicação em HF em regiões de baixa latitude. 2020. xv, 89 f., il. Dissertação (Mestrado Profissional em Engenharia Elétrica)—Universidade de Brasília, Brasília, 2020.
Abstract:	The selection of propagation frequencies for High Frequency (HF) links is based on several factors, largely due to the dynamic conditions of the ionosphere. This characteristic led to the creation of several prediction models, which are well adapted to certain geographic regions and conditions of the ionosphere, but have been showing certain inaccuracies when applied in low latitude regions, such as the Brazilian Amazon. In addition, in recent years, several tools have been developed to mitigate typical HF problems, especially the Automatic Link Establishment (ALE) technique, but there is still no standardized method for defining transmission frequencies to be employed by this technique. In addition, there is a need to ascertain the impact on the HF links of disturbances that occur in the ionosphere in Brazilian territory, such as the Equatorial Spread-F (ESF). In this work, a comparative analysis was carried out based on empirical data of the prediction models of the Frequency of Optimum Transmission (FOT) of links in HF via ionosphere, in order to identify the model that best fits in the low latitude Brazilian territory and to indicate necessary adjustments. The time of occurrence of the ESF and its impact on the degradation of the Signal-to-Noise Ratio (SNR) of the links in HF were also evaluated. Based on the empirical data, an attempt was made to establish a procedure that allows the operator of systems in HF via the ionosphere to determine frequency values that increase the chances of successful communication, when using the ALE technique. When this procedure was applied, a significant increase was obtained in terms of link availability and SNR.
Unidade Acadêmica:	Faculdade de Tecnologia (FT) Departamento de Engenharia Elétrica (FT ENE)
Informações adicionais:	Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, Mestrado Profissional em Engenharia Elétrica, 2020.
Programa de pós-graduação:	Programa de Pós-Graduação em Engenharia Elétrica, Mestrado Profissional
DOI:	http://dx.doi.org/10.26512/2020.10.D.40178
Aparece nas coleções:	Teses, dissertações e produtos pós-doutorado

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