Design Of Spectrum Analyzer By Visual Instrument

A design of spectrum analyzer based on Visual Instrument (VI) technology is introduced in this paper. The spectrum analyzer has the same functions as a traditional spectrum analyzer, and also has a customized, friendly user interface. Its main functions include: 1) signal real-time display in time scale; 2) signal real-time power spectrum display in frequency domain; 3) filter, with an option of IIR and FIR filters, IIR filters include LPF, HPF, BPF and BSF in Chebyshev, etc; FIR also includes Kaiser filter and windows filter. 4) noise addition, add Gaussian Noise to generated signals to simulate actual signals. 5) parameter setting, set waveform display mode and meter scale, etc. 6) print and save, to save or print the output of display. Both actual input from DAQ card and simulation can be selected as the input. In hardware design we use PC and DAQ card (PCI-6221) to replace the traditional spectrum analyzer, which is complicated in both electrical circuit design and operation. Labwindows/CVI is the software development tool which can also support to achieve algorithm design of IIR and FIR filters.The first chapter introduces development history and current progress of VI technology. The second chapter introduces the basic theory of VI and spectrum analyzer. In the third chapter, the program realization of a VI spectrum analyzer is given. In the fourth chapter, the realization of both IIR and FIR filters are illustrated, such as Elliptic filter in IIR and Hanning windows filter in FIR. The last chapter makes summary in general.The experiment data is also given in the paper. It proves that the spectrum analyzer based on VI is practical and achievable.