The Research Of The Measure For The Distortion Of Sine Signal Based On DSP

In the design and application of electronic engineering, both in open circuit and in closed circuit, signal is certainly affected by environment, the status of the transport network and the change of parameters of the component applied. Then the characters of useful information will be changed more or less and the change is generally called as distortion, namely so-called signal distortion. Signal distortion includes three kinds of distortion: frequency, phase and waveform. The waveform distortion is caused by the nonlinearity of the amplifier circuit, so it is often called as nonlinearity distortion. The nonlinearity distortion also include harmonic distortion and intermodulation distortion.We can test the character of the transport network by detecting the nonlinear distortion and this is useful to improve the character of the network. In the generation, transport and reception of signal, we must carefully analyze and handle distortion. Kinds of nonlinear distortion meters have been widely used in many fields such as electronics, electricity and communication, and so on. The distortion meters used in common generally be divide in two kinds as the theory of test. They are the method of suppressed first frequency and the method of frequency table analysis. Most of analog distortion meters apply the method of suppressed first frequency. But thedisadvantages are need to supply the first frequency and the lower test precision of the low frequency. The method of analysis frequency table is using the meter of frequency table to test all kinds of frequency and then calculate the distortion of the wave. But the meter of analysis frequency table is more expensive.As the development of micro-computer and singlechip, especially the DSP chip, The paper advance a method of measure the distortion of sine signal, which is using the DSP chip to carry out the FFT to get the magnitude of all kinds of frequency then using the formula to calculate the distortion. The paper first introduce the measure method of generally distortion meter of internal and overseas and the application of the meter and secondly compare several measure methods, then choose the best method and expound how to carry out this measure method in hardware and software. Using matlab emulate the method and show the result. At the last give the error analysis of hardware and software during the measurement and the summarize.