Study On The Acquisition, Documentation And Analysis Of Radar Signal

With the development of modern computer technology, virtual instrument has become the main development direction of modern instrument. Virtual instrument is playing a more and more important role in the field of measuring, testing and experimental teaching.The concept and the designing processes of virtual instrument are summarized in this thesis. Also, a small instrument is designed, which can acquire, display, analyze the signal and store the data into the hard disk. It can be used as a multi-functional instrument in the process of experimental teaching. Compared with ordinary oscilloscope, it has advantages as below:firstly, the data can be stored without loss in the case of a long time, continuous acquisition in the storing functionality; secondly, the data display and spectrum analysis functionalities are combined together; thirdly, for non-stable signals, the functionality of three dimensional display of its time and frequency spectrum is provided.A data acquisition board and a common personal computer are combined to construct a system which can acquire, display, analysis the signal and store the data into the hard disk. In these functions, the data is acquired by the acquisition board; the storing part store the data into the hard disk, the instantaneous storing functionality store the data at a time, and the continuous storing functionality store the data from a time to the end; in analysis part, the analysis of fast Fourier transform for the stable signal or short time Fourier transform for the non-stable signal is supplied; the last, display both data wave and spectrum on the screen, the display of STFT is three dimensional in the time, frequency and power axis. The methods used in this thesis are shown below:The Multi-thread technology is used for the Multi-thread system architecture. For the different functionalities, multi-thread architecture is used, which could not only improve the utilization rate of CPU, but also enhance the operation speed of the system.The memory file mapping technology is used for long time continuous storing. The difficulty of the implementation of long time continuous storing functionality is that the data in the memory should be swapped to hard disk as soon as possible, for the time would influence the refreshing rate of the data wave. Here, the memory file mapping technology is used to solve this problem. The OpenGL technology is used for the three dimensional display of the time and frequency spectrum of signal. This could deepen the understanding of users to the time and frequency spectrum of signal.The result shows that, using virtual instrumental technology, not only the required functionalities could be implemented; it also has other advantages derived from the intrinsic feature of virtual instrument, that is, lower cost, easy to design, convenient to expand.