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Authors
Abstract(s)
Desde o inicio da utilização de radares pelos militares que é conhecido o facto
da vulnerabilidade da localização do transmissor quando se encontra a transmitir.
Não só por este caso, mas também pelo pelo custo elevado de um transmissor, o
radar passivo apresenta-se como uma solução ideal a todos estes problemas. No
entanto, como tudo, tem as suas desvantagens, realçando não se controlar o sinal
que é transmitido pelo iluminador de oportunidade e este não estar otimizado para
sistemas de radar, o que no final, implica um processamento mais complexo.
Este conceito de radares passivos não é uma ideia recente. A primeira
experiência realizada remonta ao ano de 1935, quando Robert Watson-Watt usara
um iluminador de oportunidade de onda curta radiada do BBC Empire transmitter
em Daventry para detetar um bombardeiro Heyford a uma distância de 8 km. Porém,
o primeiro radar passivo foi desenvolvido uns anos depois pelos alemães, denominado
Klein Heidelberg.
A presente dissertação objetiva analisar e ampliar o conhecimento existente
na literatura através do estudo de sistemas de radar passivo para a deteção de alvos,
usando como iluminador de oportunidade, a televisão digital terrestre, Digital Video
Broadcasting - Terrestrial (DVB-T) e, simultaneamente, elaborar um trabalho de
desenvolvimento sobre radares passivos, processamento de sinal nos mesmos, teoria
de antenas e formação de imagem utilizando radares passivos. Esta dissertação
tem ainda como objetivo o desenvolvimento de um sistema de radar passivo que
permita a deteção de alvos utilizando DVB-T. Em jeito de conclusão e em função
dos resultados obtidos pretende-se discutir possíveis cenários de implementação na
Marinha Portuguesa.
Since the beginning of the use of radars by the military it is known the fact of vulnerability in the location of the transmitter when it is operating. It is not only by this specific reason, but also because of the pollution of the electromagnetic spectrum or the high cost of a transmitter, the passive radar is an ideal solution to all these problems. However, like everything, it has its disadvantages, such as the signal that is transmitted by the illuminator of opportunity is not controlled and it is not optimized for radar systems, which in the end, implies a more complex processing. The concept of passive radars is not a recent idea. In fact, the first experiment carried out dates back to the year of 1935 when Robert Watson-Watt used a BBC Empire transmitter shortwave illuminator of opportunity in Daventry to detect a Heyford bomber at a range of 8 km. However, the first passive radar was developed a few years later by the Germans, called Klein Heidelberg. This dissertation has as main objective the research of a passive radar system, using DVB-T as an illuminator of opportunity and, simultaneously, to develop a development work on passive radars, its signal processing, basic theory of antennas and passive radars for image formation. This work has also an objective of developing a passive radar system using DVB-T. As a conclusion and based on the results obtained, it is intended to discuss possible implementation scenarios in the Portuguese Navy.
Since the beginning of the use of radars by the military it is known the fact of vulnerability in the location of the transmitter when it is operating. It is not only by this specific reason, but also because of the pollution of the electromagnetic spectrum or the high cost of a transmitter, the passive radar is an ideal solution to all these problems. However, like everything, it has its disadvantages, such as the signal that is transmitted by the illuminator of opportunity is not controlled and it is not optimized for radar systems, which in the end, implies a more complex processing. The concept of passive radars is not a recent idea. In fact, the first experiment carried out dates back to the year of 1935 when Robert Watson-Watt used a BBC Empire transmitter shortwave illuminator of opportunity in Daventry to detect a Heyford bomber at a range of 8 km. However, the first passive radar was developed a few years later by the Germans, called Klein Heidelberg. This dissertation has as main objective the research of a passive radar system, using DVB-T as an illuminator of opportunity and, simultaneously, to develop a development work on passive radars, its signal processing, basic theory of antennas and passive radars for image formation. This work has also an objective of developing a passive radar system using DVB-T. As a conclusion and based on the results obtained, it is intended to discuss possible implementation scenarios in the Portuguese Navy.
Description
Keywords
Radar Passivo Deteção Processamento de Sinal DVB-T (Digital Video Broadcasting - Terrestrial)