Digital signal processing experiment one T3

Subject requirements

A continuous periodic square wave signal frequency is 200Hz, the signal amplitude between -1 + 1V, which is required to display the graphics window on two periodic waveforms. At 4kHz frequency sampling the continuous signal, generating a programming signal and a discrete signal which is a continuous waveform obtained by sampling.

principle

Digital signal processing ppt chapter 1

The point is that the formula
$w_0=2\pi \frac{T}{T_0}$
I.e., a period of continuous signal and a sampling signal period obtained digital frequency .
In this question, the continuous signal period $T_0=\frac{1}{200}s$ , sampling signal period$T=\frac{1}{4000}s$ .
Thus,$w_0=2\pi \frac{T}{T_0}=\frac{Fr.}{10}rad$
We will sample in one period$N=\frac{2p}{w_0}=20$ points.

Implementation

The usage of the square function
f=square(a*t)
generates a period T= $\frac{2p}{a}$The square wave function of
this problem is to generate $T=\frac{1}{200}$The square wave signal of$s$ ,
so$a=400\pi$

Code

clear all
clc

%生成1~1/100间隔为1/4000的向量
t = 0:1/4000:0.01;
%通过square产生一个方波序列
f1 = square(400*pi*t);
%绘制图形,放在子图1
subplot(2,1,1);
%绘制离散图
stem(t, f1);
%绘制图形,放在子图2
subplot(2,1,2);
%绘制连续图
plot(t,f1);
%定义XY轴长度
axis([0,0.01,-1.5,1.5]);