Design And Research On RF Virtual Frequency Spectrum Analyzer Based On Digital Intermediate Frequency

With the rapid development of communication, especially the mobile communication technology. RF frequency spectrum analyzer as communication measurement instrument in the research, manufacture and maintenance of the communication equipment is needed urgently, and its application is wider and wider. However, because the structure of frequency spectrum analyzer instrument is very complex, the market is nearly monopolized by a few large overseas companies, it is so expensive that its popularization is greatly blocked.Aiming at this problem, Wuhan University of technology associating with Hubei Zhongyou Technology Co. Ltd developed the RF frequency spectrum analyzer of this subject. Besides, the advantages of low developing and maintenance expense of the virtual instruments, strong reuse property, low price as well agility, it used the idea of the software radio for reference and adopted the digital intermediate frequency, which does not only overcome the shortcoming of the complex structure and the simple function of the traditional analog frequency spectrum analyzer instrument, but also resolve the problem that digital frequency spectrum analyzer instrument used widely in the present can only measure the low frequency signal. At the same time, from the method of specific realization, we used DSP chip as the embedded microcomputer of instrument host computer. It can not only realize the control function of the common microprocessor, but also do some high real time of digital signal processing together with virtual instrument of PC. The points mentioned above are all the innovations of this subject.In order to overcome the disadvantages of the existed frequency spectrum analyzer instrument, the idea of software radio was applied, and a scheme of RF virtual frequency analyzer instrument based on digital intermediate frequency was presented, then its feasibility was analyzed. Sample error probably caused from data collection circuit of RF virtual frequency spectrum analyzer instrument was emphasized, and some kinds of selectable resolution scheme were presented, then these schemes of advantages and disadvantages were compared and summarized by the way of theory analyse, Matlab simulation and practice validate and so on, at last, the optimum scheme of RF virtual frequency analyzerinstrument was decided and adopted. At the same time, this subject set up the software structure system of RF virtual frequency spectrum analyzer instrument, analyzed every level algorithm of software, and discussed the algorithm of digital signal processing, at last, we realized the algorithms with VC++ language.