Research On Key Technology Of Plasma Permeable Simulation Test System

With further exploration of the universe and the rapid development of science and technology,"communications blackout" in near space has become a problem to be solved immediately.Ever since the United States and the Soviet Union made the first step,human beings have made unremitting efforts and researches on it.From theory to practice,most of the studies are devoted to the characteristics of plasma itself,or its test via adoption of existing test equipment.However,few scholars have been involved in plasma penetration test system comprehensively.Therefore,it is urgent to design a set of test equipment for the study on penetration characteristic of plasma.Firstly,the problem of "communications blackout" caused by plasma is introduced in this paper.Then in terms of penetration,scattering and modulation characteristics of plasma,related test equipment and methods employed by scholars in and abroad are highly emphasized and analyzed.Based on this,a set of broad band,software-definable wave penetration test system is proposed.Secondly,on the basis of theoretical analysis,this paper presents a softwaredefinable T/R module design,which facilitates tests on penetration characteristic of plasma in HF,L and S frequency band.For the transmitter,in modulation mode,the highest transmission power can be up to 23dBm;While in point frequency mode and low sweep frequency mode,the highest transmission power can be up to 30 dBm.For the receiver,it's featured by wide band and low noise coefficient.At the same time,a matching antenna scheme is designed for the T/R module,and some antenna indexes in practice are processed.Furthermore,this paper puts forward a design of full coherent frequency synthesizer,finally realizing the global digital clock and local oscillator signal needed by the system,as well as the ADC sampling clock.The excellent phase noise and frequency stability ensure the system good performances.And a DDS+FPGA plan is advanced in this paper for frequency hopping and modulation source,and relevant processing tests are therefore developed.As a result,this equips the frequency modulation,amplitude and phase control with desirable high precision,making multiple digital modulation modes available.In response to the large dynamic range of attenuation of electromagnetic waves by plasma,this paper proposes a high speed and high dynamic range ADC+FPGA+FLASH data acquisition and storage plan.Meanwhile,together with LabVIEW software and FPGA board of NI,a series functions,including overall system control,monitoring,channel selection,gain control and the design of upper computer control program to trigger instructions are realized.Besides,the interface is simple and highly definable.Finally,tests on penetration characteristic of plasma are launched through simulating plasma layers by means of side-by-side fluorescent lamps.