The Research Of The Spaceborne Multi-function Plasma Sounding System And Its Waveform Technology

After our country's tens of years' effort, the space born sounding equipments can cover almost every research field now. However, we still lack of the system that can display the 3D plasma distribution and dynamics characteristics of Magnetosphere in real time. In order to fulfill the requirement, in this thesis, we prepare to design a light, low power, and multi-function space born wireless remote sensing system, which can detect the plasma distribution and dynamics characteristics of Magnetosphere. The system can provide many parameters of the echoes, including:amplitude, phase, frequency, Doppler frequency, distance, angle of arrival, polarization. Under its active mode, the system can perform Magnetosphere sounding, topside Ionosphere sounding, and big scale target sounding on the ground; under its passive sounding mode, the system can detect the space EMI background and low frequency plasma wave radiation; by using multi-numbers of the system and choosing the right satellite orbits, they can work on the network mode, and depict the panorama of the space plasma near the earth in real time.In this thesis, according to the requirements of the different space plasma region, we design different detecting waveforms. Using advanced software, hardware, DSP and related technologies, we build the system blocks, such as system timing, correlation, data communication and data processing. We build the system hardware platform, realizing modularization and hardware control flow, and make it compatible to different kind of system. The implementation of the project is of great scientific meanings and significant engineering values. At the same time, it can provide necessary technique preparation to our country's Mars'Ionosphere sounding plan,. The main research works of the thesis are:1. For the first time, the concept of space born multi-function plasma sounding system is put forward in this thesis. Under its active mode, the system can perform Magnetosphere sounding, topside Ionosphere sounding, and big scale target sounding on the ground; under its passive sounding mode, the system can detect the space EMI background and low frequency plasma wave radiation; by using multi-numbers of the system and choosing the right satellite orbits, they can work on the network mode, and depict the panorama of the space plasma near the earth in real time.2. For the first time, bi-phase inter-pulse coded coherent pulse train with batch-to-batch diverse PRI is put forward in this thesis. The new waveform eliminates the "dead zones" of conventional evenly spaced bi-phase inter-pulse coded coherent pulse train. What's more, the new waveform possess all the merits of conventional evenly spaced bi-phase inter-pulse coded coherent pulse train, such as high range resolution, high Doppler resolution, big unambiguous detection range, high coding gain, low transmission power. The new waveform fits to sounding the middle and far range target in Magnetosphere without "dead zones"3. The system design combines software and hardware method. The building of the system is mainly in software mode, using advanced DSP technologies. So, the system can be easily upgraded by up to date DSP and Radar technologies. Because of its embedded hardware structure, the system can fulfill the low weight, low volume and low power requirements of space born equipments. The open system structure designation make it possible to realize complex function, and make it more compatible and more agile to realize different sounding requirements by different software but under the same hardware platform. On the same hardware platform, utilize time-sharing operation to realize active and passive sounding. The coherence of the system structure makes it easy to fulfill the system modularization. So the system becomes more open, compatible, and expansible.The contents of the thesis are arranged as:1. Expatiate the meanings of develop such space born radio plasma sounder, and introduce the general situation of this research field inside and outside the country.2. Expatiate the principle of such space born radio plasma sounder in detail. Then compare it with Ionosonde, and summarize the differences of the two equipments.3. Finish designing the radar waveforms of such space born radio plasma sounder, including single pulse, evenly spaced pulse train, bi-phase intra-pulse coded pulse trains, bi-phase inter-pulse coded pulse trains. Deeply compare and analyze the timing, spectrum and ambiguity functions of these waveforms. Build the open loop testing platform and make comparison to the open loop testing results of the waveforms.4. Finish designing the radar waveforms of bi-phase inter-pulse coded coherent pulse train with batch-to-batch diverse PRI, and Gaussian pulse. Deeply compare and analyze the timing, spectrum and ambiguity functions of these waveforms. Build the open loop testing platform and make comparison to the open loop testing results of the waveforms.5. Design the structure of the full system, and give the system parameters. Deeply analyze all the key techniques of the system.6. Summarize the whole research work of this thesis, make assumption and prospection of the next step work.