GPS导航系统再入黑障现象地面再现实验

Experiment on reproducing the continuous blackout of the GPS system

针对飞行器以超高声速再入大气层时,表面产生等离子体,等离子体会降低电磁波信号的传播,严重时会造成导航中断的问题,理论计算了等离子体对全球定位系统导航信号的衰减,并分析了全球定位系统接收信号的功率阈量;利用低气压辉光放电原理在地面产生大面积、长时间稳定的可控等离子体,在实验室环境下持续再现了等离子体下全球定位系统导航信号正常接收、黑障产生、持续、消失的过程,实验测量了等离子体的衰减和接收机的功率阈量.实验结果表明,等离子体下全球定位系统接收信号的衰减临界值与接收机本身的功率阈量相差不到0.5dB,数值几乎一致;实验模拟了飞行器再入过程中等离子体下全球定位导航系统通信黑障前后的工作过程,再现了等离子体下全球定位系统导航正常、失败、重新定位的过程.这为导航系统的通信黑障研究和再入通信的接收机设计提供了参考.

The plasma induced in the reentry can degrade the electromagnetic system,even producing the blackout when it is serious.Then the attenuation of the GPS signal by the plasma is calculated and the power threshold of the received signal is analyzed.An experiment on the continuous‘acquisition-blackoutreacquisition＇process of GPS system is successfully reproduced by plasma in an ordinary lab.The plasma is excited by a low-pressure glow discharge and it is a long-lasting,large-scale,non-magnetic plasma.The plasma density can be easily controlled by RF power,achieving an arbitrary variation of plasma density.Comparing the critical attention with the standard power threshold of the receiver,results indicate that both the values are almost the same and that their differences are less than 0.5dB.The blackout occurs as the attenuation is greater than the threshold.The experiment is valuable for the research on other navigation systems＇ blackout and the design of reentry receivers.