“黑障”测控传输体制研究

【作者】 刘昌臻；

【导师】 顾继慧；

【作者基本信息】 南京理工大学 ， 通信与信息系统， 2012， 硕士

【摘要】 “黑障”是人类继克服了“音障”、“热障”之后在高速飞行研究中所面临的又一关键难题,同时也是人类在发展航天事业过程中遇到的障碍之一。航天器再入大气层过程中与其周围空气激烈摩擦而产生的等离子体对射频电磁波的幅相效应将造成通信中断“黑障”。自上世纪60年代初以来,为了减轻甚至消除再入等离子体鞘套所产生的“黑障”对通信的影响,人类一直在苦苦探寻着,希望通过理论研究以全面了解“黑障”区的电磁特性,以确保地面站与航天器之间的通信无阻。为此,国内外业内专家在理论研究、数值仿真、室内实验及飞行试验等方面开展了大量工作,并取得了一些进展。本论文通过对再入过程中航天飞行器在不同射频工作频段、处于不同再入高度时的“黑障”特性分析及“黑障”区不同调制解调系统信息传输误码率的计算和比较,从中对比出各调制体制的优劣,并分析了目前消除“黑障”效应措施的工程可行性,为载人航天飞行器的测控系统应用奠定理论和工程基础。本文首先对“黑障”区电磁特性及电磁波在“黑障”区的传播特性进行理论分析、公式推导和仿真计算,然后根据数字通信原理建立“黑障”区等离子体环境下信道仿真模型,据此模型获取2ASK、2FSK和2PSK三种调制体制分别在相干、非相干解调方式下误码率的计算流程图,继而推导出各自误码率的计算公式,并计算各波段射频电磁波在不同高度时各种调制解调系统的误码率,由此对比各种调制体制的优劣。最后分析总结现行各种减轻“黑障”的方法和措施以比较各自的工程可行性和有效性。更多还原

【Abstract】 "Blackout", one of the barriers faced by human being in the development space industry, is another key problem after overcoming "sound barrier ", "thermal barrier" in high-speed flight research. The plasma is generated when the spacecraft rubs against the surrounding air intensely in reentry atmosphere process, and the amplitude and phase effects of the plasma on radio frequency electromagnetic wave will result in the interrupt of communication -" blackout ".Researchers from the late 1950’s begin seeking for the effective approaches to reduce the problem of interruption during the reentry communication. It is hoped through the theoretical study to fully understand the electromagnetic properties of the "Blackout" area to ensure the smooth communication between the ground station and the spacecraft. Therefore, experts home and abroad have conducted a great deal of studies and made great progress in the theoretical research, numerical simulation, indoor experiment and the flight test.This paper analyzes the characteristics of the "Blackout" emerged when the spacecraft of the different speeds, of the different frequency bands and of different reentry height, and computes and makes a comparison to the information transmission bit error rate between the different modulation and demodulation systems,then compares the advantages and disadvantages of the three modulation systems. Finally it proposes the feasible engineering measures to eliminate the "Blackout", and that helps to build a solid theoretical and practical foundation to the application of the manned space flight communication-system.First of all, this paper refers to the electromagnetic characteristics of the "Blackout", and studies on the theoretical analysis, formula deduction and simulation calculation of the spreading characteristics of electromagnetic wave in "Blackout" Area. And then, based on the principles of digital communication, a channel simulation model is established in a "Blackout" plasma environment. The bit error rate calculation flow charts of the three modulation systems namely 2ASK,2FSK and 2PSK are made in coherent and incoherent demodulation mode, then deduces the respective bit error rate calculation formula, and calculated the band RF electromagnetic wave at different height of various modulation and demodulation system bit error rate, whereby the analysis summed up the advantages and disadvantages of the three modulation systems. Finally, this paper analyzes the feasibility and effectiveness of the various approaches and measures to reduce the "Blackout".更多还原