Research On Techniques Of Signal Acquisition And Storage For Incoherent Scatter Rader

Incoherent Scatter Radar (ISR)，as a method of detecting features of upperatmosphere through the scattering signals of thermal fluctuations of electrons andplasma, has been proved to be the most powerful ground-based instrument for theexploration of the ionosphere. The weak echoes of ISR have low Signal to Noise Ratio(SNR).At the same time, ISR has huge data volumes. In the view of above reasons,high demands on signal acquisition and storge techniques are required.According to the actual requirements of ISR signal processing, this paper focusedon the high-precision, high-speed AD design and data-storage technology. Firstly,studied on the principles of the ADC front-ended conditioning circuit, two designs offront-ended condition circuit are proposed which have low noise and variable gain. Andalso, the PCB design is described in details in this paper. Secondly, by analyzing thesampling-clock generation methods, two sampling-clock generation circuits based onlow jitter clock synthesized chips are proposed. Taking the impacts of sampling-clockjitter on the dynamic range of ADC into account, the performance of the sampling-clockis tested. Both of the designs achieved good results. Thirdly, two different digitalquadrature sampling methods, which are based on Bessel interpolation and Low-passfilter respectively, are focused on in this paper. The simulation of the two methods andcorresponding FPGA modules are given.Fourthly, in consideration of the actual needs ofthe original data processing, data return and storage design based on USB is proposed.And the corresponding software is developed. Finally, linking and debugging jobs withother units in the outfield are described in detail.The theories and designs presented in this paper have been applied to theincoherent scatter radar signal processing system, achieving good results, and greatvalue for the similar systems.