Description: DFT进行频谱分析时的三种现象
1、混叠：对连续信号采样，要求连续信号是带限的，采样频率要足够高。Fs应满足Nyquist采样定理才不产生混叠。
采样前加低通滤波器防混叠
2、频谱泄漏：DFT对时域信号进行了截断（相当于采样信号乘了一个窗函数），时域的乘积相当于频域卷积，改变了原信号频谱。
改用其他窗函数（非矩形）改善泄漏。
3、栅栏现象：DFT 只给出了频谱在采样点上的取值，采样点间的频谱内容丢失。-DFT spectrum analysis of a three phenomena, aliasing : continuous signal sampling, requiring continuous signal is band-limited, the sampling frequency should be high enough. Fs meet the Nyquist Sampling Theorem would not have aliasing. Sampling former low-pass filter plus anti-aliasing 2, spectrum leakage : DFT right time domain signal a disconnect (equivalent to a sampling signal by a window function). time domain is equivalent to the product of frequency-domain convolution, changes in the spectrum of the original signal. Window functions to switch to other (non-rectangular) to improve leakage. 3, fenced phenomenon : DFT spectrum is given only at the sampling point value, sampling points of the spectrum as lost. Platform: |
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Author:qinyang |
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Description: 数字信号处理实践方法，从一到三囊括了数字信号处理的模数变换、DFT变换、Z变换、滤波器设计等-Digital signal processing practices, from 1-3 to include digital signal processing of analog-to-digital transformation, DFT transform, Z transform, filter design, etc. Platform: |
Size: 9216 |
Author:hbeishang |
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Description: 本程序为一个用matlab实现的语音滤波程序，能计算并显示语音信号的幅频特性，巴特沃斯低通滤波器幅度和相位响应，引入噪声后的幅频特性，以及滤波后的DFT幅频特性。本程序附有语音文件以供试验。-This program is an implementation using matlab voice filtering procedures, can calculate and display the speech signal amplitude-frequency characteristics of Butterworth low-pass filter magnitude and phase response, after the introduction of noise, amplitude-frequency characteristics, as well as the filtered DFT amplitude-frequency characteristics. This procedure for testing with voice file. Platform: |
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Author:周峰 |
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Description: 本文介绍了数字信号处理中各种算法基本原理，包括Z 变换、DFT 变换及其快速
算法FFT 等信号变换算法和包括IIR 与FIR 数字滤波器的设计与实现，详细论述了利用
MATLAB 软件对信号变换和设计数字滤波器的原理﹑ 步骤和实现方法，并给出了基于
MATLAB 的模拟与仿真。文章最后给出了实验结果，并就其结果做了进一步的解释和说明。
关键词：Z 变换，离散傅立叶变换DFT，数字滤波器，系统结构仿真
-This article describes a variety of digital signal processing algorithms in the basic principles, including the Z transform, DFT transform and its fast algorithm FFT and other signal transform algorithm and including IIR and FIR digital filter design and implementation, discussed in detail by using MATLAB software, the signal transformation The principle and design of digital filters ﹑ steps and implementations, and gives MATLAB-based simulation and emulation. Article Finally, the experimental results and the results made on the further explanation and clarification. Key words: Z transform, discrete Fourier transform DFT, digital filter, system architecture simulation Platform: |
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Author:zhd |
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Description: 本文件为一个word文档。本文档基于MATLAB平台设计了带通滤波器，滤除信号中特定频率成分，具体功能word中有详细说明。本文件旨在通过一个简单的实例，说明基于MATLAB的数字滤波器设计原理，并在最后总结了数字滤波器的设计规律，文件内容对初学者有很大的帮助。-This document is a word document. This document is based on MATLAB platform design bandpass filter, filter out specific frequency component signal, word specific functions are described in detail. This document aims through a simple examples to illustrate the digital filter design based on the principle of MATLAB and concluded the design rule of the digital filter, the file content is very helpful for beginners. Platform: |
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Author:wangfeng |
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Description: 经常在实训中用到的相关MATLAB代码，有dft，傅里叶变换，低通滤波器的响应等基础代码-Often used in practice are in the MATLAB code, DFT, the Fourier transform, the response of the low-pass filter based code Platform: |
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Author:LGD |
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Description: 调用自定义函数解决题目：
1.读取自然图像、生成合成图像、高相关图像、高去相关图像，完成压缩
2.得到傅里叶变换后的图像
3.fft中心变换\walsh变换，进行两种变换的对比
4.得到傅里叶变换后的图像和傅里叶变换需要的时间，显示变换后的图像，显示傅里叶变换时间随图像像素的变化
5.显示不同阶数butterworth高通滤波和低通滤波滤波器的传递函数和处理后的图像
6.调用butterworthw.m，显示原图像、原图像频谱、低通滤波、高通滤波的传递函数，以及滤波器处理后的图像
7.拉普拉斯高斯滤波器进行滤波处理图像，同时显示原图像和滤波处理后图像
8.增强的图像，同时显示原图像、增强图像、再次增强图像和它们的直方图
9.kirsch\sobele提取图像边缘并显示，同时显示自然图像、合成图像、它们kirsch提取边缘处理的图像、它们sobel提取边缘处理的图像，便于对比
10.压缩，并显示不同像素值的图像；得到傅里叶变换后的图像、傅里叶变换、傅里叶中心变换需要的时间(Program the Discrete Fourier Transform (DFT) and time this program to see how it
varies as a function of the image size.
Implement the Laplacian of the Gaussian filter on different images and determine the
different results for the different standard deviations.
Implement two of the edge detection operators (Kirsch and Sobel) and compare their
respective results as a function of their edge data extraction for a same gray scale
threshold.) Platform: |
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Author:malvina
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Search - DFT filter matlab