Research And Implementation Of Digital Distortion Instrument Based On DSP

The distortion degree of electronic measurement is a very important parameter, and it is very important for the development of electronic and information engineering to measure it accurately.There are two main existing methods to measure the distortion degree:spectrum analysis and fundamental wave rejection. The fundamental wave rejection is mainly used in the analog instruments. Analog measurement instruments of the distortion degree costs high, and their lives are not long, and it is difficult to improve the precision of the distortion degree measurement.Spectrum analysis method is adopted to measure the distortion degree by most digital instrument, and the basic theory of spectral analysis is fast Fourier transform. But fast Fourier transform has a problem of spectral leakage. If no measurement is provided to improve the algorithm, using FFT (Fast Fourier Transform) directly to measure the distortion degree, the error will be very large. In order to reduce spectral leakage, a kind of window is added. Adding window can significantly to reduce spectral leakage, but it can not eliminate spectral leakage, and it will reduce the resolution of the spectrum.According to the basic principle of software radio, this paper puts forward a new method to reduce the bad influence of spectral leakage in measuring the distortion degree. The new method is based on interpolation filter, at same time we adjust the signal frequency to a particular frequency point, and use relative algorithm to ensure the synchronous sampling, thus the influence of spectral leakage in measuring the distortion degree can be reduced. The algorithm has been simulated using MATLAB. At the same time, the hardware circuit of the digital instrument to measure the distortion degree has been developed, in which TMS320C5402+STC89LE58RD is used as the core.The actual test proves that the distortion degree algorithm is feasible and the design of hardware is reliable, but some deficiencies still exist. In this paper these deficiencies of the digital instrument of the distortion degree are analyzed further, and the next research direction is pointed out.