FFT-spectrum-analyzer数字信号处理第二次大作业.docxVIP

FFT spectrum analyzer based on Matlab NAME ： XXXXX Student ID ： 00000000000 Professor ： 何 岭 松 Date ： 2013-10-08 Abstract Fourier transform is powerful method in signal process. It can transform the signal from time domain to frequency domain. In frequency domain some characteristic is more obvious than it in time domain. For the discrete signal, there is Discrete Fourier Transform (DFT). But the amount of calculation in DFT is large, to speed up in calculation, there is Fast Fourier Transform (FFT). For DFT and FFT, as the spectrum is discrete, and only the frequency sampling point is calculated, it caused the fence effect. And the energy leakage for cycle extension. To reduce the fence effect, window function is needed. In this project, FFT is used to analyze the spectrum of the signal. The signal can be generated in three ways, signal generator, read from wav files and input from the sound card. To reduce the fence effect, window function is supported. Keywords: FFT wav file sound card input window function Content TOC \o 1-3 \h \z \u 1. Introduction 1 2. Method 2 2.1 Signal spectrum analysis 2 2.1.1 Continuous Fourier Transform 2 2.1.2 Discrete Fourier Transform (DFT) 2 2.1.3 Fast Fourier Transform (FFT) 3 2.2 Window Function 3 2.3 Signal Source 4 2.4 Zoom spectrum 5 3. Results 5 3.1 Interface of the program 5 3.2 FFT the signal from signal generator 7 3.3 Read the wav file and spectrum analysis 9 3.4 Sound card input and spectrum analysis 10 3.5 Zoom FFT 10 3.6 Window function 10 4. Conclusions 13 5. References 13 Signal Generator based on Matlab PAGE 1 1. Introduction One of the most commonly used method in signal processing is the spectrum analysis. It transform the signal from time domain to frequency domain. For some signal, the time domain analysis is very difficult, and some characteristics is hard to obtain from time domain analysis, such as if the signal has a cycle,