| Satellite covert communication system has better communication performance and strong capability of anti-interception, attracting more and more attention in recent years. According to different business scenarios, the communication system is designed to meet the communication needs and maximize the stealth performance of the system in this paper.Firstly the physical layer framework of satellite covert communication system is elaborated, and the different channel coding, modulation, advantages and disadvantages of spread spectrum strategy is summarized. In accordance with the system requirements for communication performance and stealth performance, the cascaded CRC-Turbo code, seven kinds of modulation, and variable spreading factor code hopping direct sequence spread is selected as the channel coding,the modulation scheme and the spread spectrum technology respectively in the scheme.Then feasibility of each module and system framework is validated by simulation. In the perspective of time domain, frequency domain, and energy domain, the influence of each module sensitive factors on communication performance and stealth performance is studied, such as communication distance, communication rate, error rate, and intercept probability. In which coding scheme refers to the code rate and code length, modulation contains modulation index and modulation order number, and spread spectrum technology refers to spreading factor. Finally, according to different business scenarios, change regularity of the communication performance and stealth performance are analyzed. In addition, the influence of different characteristic parameters on the performance of the system is studied based on model of communication rate and probability of interception respectively. On the premise that the parameters meet the requirements of the communication rate in the simulation, the code rate, the modulation method and the spread spectrum factor are changed to get better anti-interception performance. |
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