With increased human activity in space, the risk of re-entry and collision between space objects is constantly increasing. Hence, the need for space situational awareness (SSA) programs has been acknowledged by many experienced space agencies. Optical and radar sensors, which enable the surveillance...
With increased human activity in space, the risk of re-entry and collision between space objects is constantly increasing. Hence, the need for space situational awareness (SSA) programs has been acknowledged by many experienced space agencies. Optical and radar sensors, which enable the surveillance and tracking of space objects, are the most important technical components of SSA systems. In particular, combinations of radar systems and optical sensor networks play an outstanding role in SSA programs. At present, Korea operates the optical wide field patrol network (OWL-Net), the only optical system for tracking space objects. However, due to their dependence on weather conditions and observation time, it is not reasonable to use optical systems alone for SSA initiatives, as they have limited operational availability. Therefore, the strategies for developing radar systems should be considered for an efficient SSA system using currently available technology. The purpose of this paper is to analyze the performance of a radar system in detecting and tracking space objects. With the radar system investigated, the minimum sensitivity is defined as detection of a $1-m^2$ radar cross section (RCS) at an altitude of 2,000 km, with operating frequencies in the L, S, C, X or Ku-band. The results of power budget analysis showed that the maximum detection range of 2,000 km, which includes the low earth orbit (LEO) environment, can be achieved with a transmission power of 900 kW, transmit and receive antenna gains of 40 dB and 43 dB, respectively, a pulse width of 2 ms, and a signal processing gain of 13.3 dB, at a frequency of 1.3 GHz. We defined the key parameters of the radar following a performance analysis of the system. This research can thus provide guidelines for the conceptual design of radar systems for national SSA initiatives.
With increased human activity in space, the risk of re-entry and collision between space objects is constantly increasing. Hence, the need for space situational awareness (SSA) programs has been acknowledged by many experienced space agencies. Optical and radar sensors, which enable the surveillance and tracking of space objects, are the most important technical components of SSA systems. In particular, combinations of radar systems and optical sensor networks play an outstanding role in SSA programs. At present, Korea operates the optical wide field patrol network (OWL-Net), the only optical system for tracking space objects. However, due to their dependence on weather conditions and observation time, it is not reasonable to use optical systems alone for SSA initiatives, as they have limited operational availability. Therefore, the strategies for developing radar systems should be considered for an efficient SSA system using currently available technology. The purpose of this paper is to analyze the performance of a radar system in detecting and tracking space objects. With the radar system investigated, the minimum sensitivity is defined as detection of a $1-m^2$ radar cross section (RCS) at an altitude of 2,000 km, with operating frequencies in the L, S, C, X or Ku-band. The results of power budget analysis showed that the maximum detection range of 2,000 km, which includes the low earth orbit (LEO) environment, can be achieved with a transmission power of 900 kW, transmit and receive antenna gains of 40 dB and 43 dB, respectively, a pulse width of 2 ms, and a signal processing gain of 13.3 dB, at a frequency of 1.3 GHz. We defined the key parameters of the radar following a performance analysis of the system. This research can thus provide guidelines for the conceptual design of radar systems for national SSA initiatives.
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문제 정의
A preliminary study considering the development of efficient SSA radar systems is being conducted by the NSSAO. The work summarized in this paper was conducted as part of this study, to analyze the performance of radar systems in detecting and tracking space objects in LEO. This paper presents a comparative study of several reference radar parameters for various frequencies, as well as design of the power budget, by means of simulation.
제안 방법
In this paper, to analyze the performance of the radar system, we defined detection of a target with a diameter of 1 m at a distance of 2,000 km, as the benchmark sensitivity. Key radar reference parameters for all frequency bands considered are shown in Table 2.
The behavior of a radar system for detecting and tracking space objects was simulated, to analyze its detection capability in terms of frequency, transmit power, and target size (measured in diameter). Two principal types of system are available with current radar technology: systems with mechanically steered reflector antennas, and phased-array antennas.
In order to further improve the SNR, coherent signal processing techniques, such as pulse compression, constant false alarm rate (CFAR) detectors, and other advanced algorithms, will be necessary in the base band, which usually require complex systems, and incur higher costs. The key parameters of the radar system were designed through a performance analysis and tradeoff study. We also showed that phased-array radar systems are the most suitable technology for detecting and tracking space objects in combination with OWL-Net.
The work summarized in this paper was conducted as part of this study, to analyze the performance of radar systems in detecting and tracking space objects in LEO. This paper presents a comparative study of several reference radar parameters for various frequencies, as well as design of the power budget, by means of simulation. These results provide the basis for development of future SSA radar systems.
이론/모형
The performance of a radar system can be estimated using the simplified radar range equation for a monostatic pulsed radar (Skolnik 1980). For such configurations, the received power, Pr, is expressed as,
성능/효과
We applied non-coherent pulse integration as a simple radar signal processing technique, during simulation. The results of power budget analysis showed that the maximum detection range of 2,000 km could be achieved with a transmit power of 900 kW, transmit and receive antenna gains of 40 dB and 43 dB, respectively, a 2-millisecond pulse width, and a signal processing gain of 13.3 dB, at a frequency of 1.3 GHz. The SNR required for an 80 % probability of detection with a false alarm rate 10−6, was assumed to be 12.
후속연구
An upgraded Space Fence system is also being developed by the US Air Force (Haines & Phu 2011; Haimerl & Fonder 2015). The improved Space Fence system, with extremely powerful S-band radar, is expected to be able to detect the returns of smaller objects, and to increase the number of observations, enabling the compilation of a more accurate and complete catalog of these events. The European Space Agency (ESA) initiated an SSA program in 2009, which includes the use of existing European and ESA assets, and development of future radar systems, for detecting and surveying all objects on the order of one decimeter in LEO (Ender et al.
We also showed that phased-array radar systems are the most suitable technology for detecting and tracking space objects in combination with OWL-Net. These results will be expected to be used for the conceptual design of SSA radar system. In particular, the analysis of the detection capabilities of the radar can provide guidelines for the development of radar systems for SSA programs.
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