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Abstract(s)
Os radares de abertura sintética passivos têm a utilidade de ser indetetáveis, visto que não requerem a transmissão de sinais. De facto, contrariamente aos
radares ativos, os radares passivos utilizam os sinais difundidos por iluminadores de
oportunidade. Estes sinais refletem nos alvos e, através de processamento de sinal
adequado, é possível estimar a posição dos mesmos. Esta característica é uma vantagem significativa do ponto de vista militar. Esta tecnologia está atualmente no
estado de maturação para radares terrestres no âmbito de controlo de tráfego aéreo
e vigilância. Foi demonstrado que os radares passivos podem ser bem sucedidos
a obter imagens terrestres, detetar vários tipos de alvos como drones, aeronaves,
embarcações e obter imagem dos mesmos.
No entanto, apesar dos desenvolvimentos mais recentes desta tecnologia, a
mesma encontra várias dificuldades, dados os desafios envolvidos. Para além disso,
é uma área que se encontra pouco desenvolvida em Portugal. Estes motivos, aliados
à necessidade de conceção de um rádio definido por software para um radar de
abertura sintética passivo, motivaram esta proposta da dissertação de Mestrado.
O objetivo da seguinte tese é desenvolver um sistema de radar passivo de
baixo custo. Para tal, foi desenvolvido um simulador 2D de radar de abertura
sintética passivo, o qual, utilizado para testar o processamento de sinal. Além disso,
foi igualmente testado, experimentalmente, um radar passivo para detetar aeronaves.
Para a realização do recetor rádio será necessário a utilização de um recetor
GNU radio, que possibilite a deteção dos sinais e do software MATLAB que viabilize
o processamento dos sinais recebidos. No final, com a junção destas duas componentes, espera-se que seja possível a deteção de alvos, de forma passiva. Para tal, serão
correlacionados os sinais de referência, transmitido do iluminador de oportunidade,
e o sinal medido, refletido pelo alvo.
Os resultados demonstram que é possível detetar a presença das aeronaves,
de forma passiva, através da comparação dos valores de correlação, ainda que, com
pouca congruência nos resultados do desvio de doppler.
Passive synthetic-aperture radars have the utility of being undetectable, due to not requiring signal transmission. In fact, unlike active radars, passive radars use the signals broadcasted by illuminators of opportunity. These signals reflect on the targets, and, through proper signal processing, it’s possible to estimate their position. This feature is a significant advantage from a military standpoint. This technology is currently in its maturity stage for ground-based radars with a purpose for air traffic control and surveillance. It was shown that passive radars can be successful on ground imaging, detecting different types of targets such as drones, aeroplanes, boats and provide its imaging. Despite the recent developments of this technology, it still has major difficulties given the challenges involved. Furthermore, it is an area that is really underdeveloped in Portugal. These factors, along with the need to design a softwaredefined radio destined for a passive synthetic-aperture radar, induced this master’s dissertation proposal. This thesis aims to develop a low-cost passive radar system. To do this, a 2D passive synthetic aperture radar simulator was created, which was used to evaluate the signal processing. Additionally, an experimental passive radar for aircraft detection was tested. In order to create the radio receiver, it will be necessary to use a GNU radio receiver, which will enable the signal detection and MATLAB software for the purpose of enabling the processing of received signals. In the end, it is expected that the combination of these two components will detect targets, passively. For that to happen, the signals will be correlated, the reference one transmitted from the illuminator of opportunity, and the measured signal that was reflected by the target. Although there is minimal agreement in the doppler deviation data, the findings demonstrate that it is possible to passively detect the presence of the aircraft by comparing the correlation values.
Passive synthetic-aperture radars have the utility of being undetectable, due to not requiring signal transmission. In fact, unlike active radars, passive radars use the signals broadcasted by illuminators of opportunity. These signals reflect on the targets, and, through proper signal processing, it’s possible to estimate their position. This feature is a significant advantage from a military standpoint. This technology is currently in its maturity stage for ground-based radars with a purpose for air traffic control and surveillance. It was shown that passive radars can be successful on ground imaging, detecting different types of targets such as drones, aeroplanes, boats and provide its imaging. Despite the recent developments of this technology, it still has major difficulties given the challenges involved. Furthermore, it is an area that is really underdeveloped in Portugal. These factors, along with the need to design a softwaredefined radio destined for a passive synthetic-aperture radar, induced this master’s dissertation proposal. This thesis aims to develop a low-cost passive radar system. To do this, a 2D passive synthetic aperture radar simulator was created, which was used to evaluate the signal processing. Additionally, an experimental passive radar for aircraft detection was tested. In order to create the radio receiver, it will be necessary to use a GNU radio receiver, which will enable the signal detection and MATLAB software for the purpose of enabling the processing of received signals. In the end, it is expected that the combination of these two components will detect targets, passively. For that to happen, the signals will be correlated, the reference one transmitted from the illuminator of opportunity, and the measured signal that was reflected by the target. Although there is minimal agreement in the doppler deviation data, the findings demonstrate that it is possible to passively detect the presence of the aircraft by comparing the correlation values.
Description
Keywords
Radar Radar Passivo Radar de Abertura Sintética Processamento de Sinal Recetor de Rádio Definido por Software