The Research Of The Ionospheric Integrated Sounding System Design And The Key Technology

As a signal reflection and refraction medium, Ionosphere is a stochastic parameter-varying channel, its characteristics change with time and space. With the rapid development of micro-electronics technology, high-speed signal processing technology, radar technology and modern network communications technology, the inevitable trend of the ionospheric sounding technological development has become miniaturization, digitization, automation and versatility. From the early analog mode to digital mode and from single point detection to a wide range of real-time multi-network observation, depending on the significant improvement of detecting automation degree, the characteristic parameters of the ionosphere is more abundant and accurate. Large-scale real-time monitoring and analysis of the ionospheric space environment can be achieved by network communication technology for the use of ionospheric data transmission and sharing.It is of great significance to the study of space weather and national defense for implementing a comprehensive diagnosis and management for the environment of ionosphere and radio wave by using the vertical detecting technology, the backscattering detecting technology, the oblique detecting technology, enviromental noise monitoring technology and so on. As the most of the traditional ionospheric sounding devices could only realize a single detection mode, building up an ionospheric integrated sounding system would be able to overcome the disadvantages of the original ionospheric sounding equipments which have the feature with less function, limited coverage, less obtaining parameters, it also can achieve the function of acquiring the omnibearing geophysical characteristics, the ionosphere channel propagation characteristics and the radio environment characteristics. From the point view of building a multi-functional ionospheric sounding syatem, this article started with the analysis of the principle and key technologies, and designed an integrated ionospheric sounding system which was based on testing instrument bus. The system is capable of ionospheric vertical detecting, oblique detecting, oblique backscattering detecting and spectrum monitoring. For enriching country space enviroment exploration, developing the ionospheric sounding techniques, studying ionosphere channel characteristics and monitoring the complex electromagnetic environment, the successful development of the system is of great practical significance and important application value.The details of the research in this thesis are as follows:1. The concept of the Integrated Ionospheric Sounding System was proposed at the first time. The system can be integrated with multiple functions, through time-sharing operating, the ionospheric vertical detecting, oblique detecting, oblique backscattering detecting and spectrum monitoring can be realized. It has the advantages of multi-detection function, small weight and size, low power, long range, high Doppler resolution, etc.2. The superiority of the PXI bus was analysed from the point view of system design. The Integrated Ionospheric Sounding System was built on PXI Bus by using the advanced virtual instrument bus technology, which leaded to high system integration level. Considering the detecting demands, we analysed some key issues which was needed to take into account, and designed the index parameters of the whole system.3. According to the demands of system design, the design principles of receiving channel was detailedly analysed. Using the mature technology and experience of HF receiver design, all parts of the Receiver RF Front-End were accomplished. Finaliy, we analysed the testing index which totally be accord with the design requirements.4. Using the advanced digital circuit design techniques to achieve the design of the IF collecting, processing and controlling module, as the core module, it contained the radar IF signal acquiring unit, radar data processing and timing controlling unit. Especially in the controlling and processing unit, the great capability of sequential controlling and data processing can be achieved in DSP & FPGA embedded hardware architecture, so the system has higher stability and scalability.5. On the basis of using the PXI bus-based GPS receiver module, we quickly realized the ionospheric oblique sounding subsystem. Subsequently, built the hardware platform of spectrum monitoring by the use of the existing high-speed RF acquisition module, and designed the virtual instrument program architecture for spectrum monitoring.6. Carried out a series of functional experiments on the Integrated Ionospheric Sounding System. Under the conditions of different time and places, depending on use different antennas, the ionospheric sounding functions of the system were verified. The experiment results showed that the developed Integrated Ionospheric Sounding System is fully capable of achieving the function of ionospheric vertical detecting, backscattering detecting and oblique detecting.