等离子体鞘套对C波段通信信号传输影响的试验

飞行器在稠密大气层超音速飞行时，由于其周围形成等离子体鞘套对通信信号的屏蔽或能量大幅度衰减效应，可使飞行器与地面间通信产生中断.以等离子体鞘套对通信信号透射相位改变和能量吸收为基本出发点，以高温激波管试验装置产生的、生存时间为几百微秒量级的等离子体鞘套为研究对象，利用四进制相移键控（QPSK，Quaternary Phase Shift Keying）调制、载波频率为7.5GHz的信号生成与测量系统获取有无等离子体鞘套时信号相位特征、眼图特征、图像传输等的对比试验结果，利用矢量网络分析系统E8362B获取了有无等离子体鞘套时透射能量衰减对比试验结果.试验结果不仅进一步证明了等离子体鞘套对通信信号能量大幅度衰减将不同程度影响飞行器与地面的正常通信；同时表明等离子体鞘套能够使QPSK信号相位特征产生改变，从而在信号解调解码后眼图特征产生严重畸变，通信系统误码率P_e 大大提高，最终导致接收端无法复现发送端发送的原始信息.

Experiment on influence of the communication signals transmission in plasma sheath

A vehicle flying in the atmosphere at transsonic velocity creates plasma sheath, and the communication signal is defiladed or its energy is attenuated by the plasma sheath, thus the communication system is discontinued between the vehicle and the signal station. The phase changed and the energy absorbed of the communication signal in plasma sheath which is made by the shock tube was studied, and the experiment of different plasma parameter was finished. Two measuring systems were built, one is the signals generator and data sampler, and its modulation is quaternary phase shift keying (QPSK), and its carrier frequency is 7.5GHz; the other is the E8362B test system. The contrastive results of the signal phase changed and the signal energy attenuated at the plasma and no plasma were obtained. The experimental results show that not only is affected the communication by the plasma sheath absorbing, but also the phase changed of QPSK signals is achieved, the signals demodulated/decoded are badly aberrant, and the P_e of communication system is increased, and the receiver is unable to offer the original information sent by transmitter.