The Impact Of Different Modulation System To The Blackout Effect

When a vehicle enters the radio blackout phase, the radio waves used for communication between ground stations and satellites are attenuated or reflected by the plasma layer that is created during hypersonic/re-entry flight and communication is interruptted. We call the phenomenon "blackout effect". This phenomenon was well known at the beginning of space exploration when space capsule would experience several minutes of radio blackout during re-entry. Nearly 50 years later, hypersonic capsules still experience radio blackout during re-entry.In this paper, we study the transmission characteristics of electromagnetic wave in the plasma more systematically.(1)Based on previous studies, the paper analysis deeply the basic characteristics of the plasma interaction with electromagnetic wave and reasonably deduced electromagnetic wave attenuation constant. And discussing the factors affecting the attenuation constant paves the way for establishing a plasma channel model.(2)The paper in-depth analysis the impact of electromagnetic wave propagation properties in the plasma. Electromagnetic waves amplitude changes over time when there is a plasma environment. The articles uses Matlab/Simulink to build a reasonable model of dynamics plasma channel. Then we can get the different transmission performance of waves in the plasma channel of different modulation system. The paper analyzes current and effective measures to alleviate the "black barrier effect", and laid the foundation of spacecraft monitoring system in theory and practice.(3)The paper discusses the approach to improve the "blackout effect" by the use external magnetic field. First, the article describes the mechanism of interaction between the electromagnetic wave and the plasma when add to the applied magnetic field, and proposes a "magnetic window" model. Then, both from the theoretical and experimental aspects, we analyze spectrum, constellation diagram, eye diagram and other performance parameters as an example of choosing BPSK modulation system. The results show that the applied magnetic field can improve the "blackout effect" effectively.The biggest innovation of this article is that most of the data analysis is based on experiments, and More credible than the simulation data. The data provide a good reference for the aerospace industry.