课题目标

使用C语言和卷积运算实现N点移动平均滤波器程序。
输入信号如下所示：
$(1)\;\;x[n]=sin(\pi n/64)$
$(2)\;\;x[n]=sin(\pi n/64)+0.2sin(10\pi n/64)+0.1sin(20\pi n/64)$
$(3)\;\;在x[n]=sin(\pi n/64)中添加功率为0.2的噪声$
N点分别设定为3，6，12，画出波形图。

一、首先实现功率为1的白噪声

白噪声通过一个头文件和源文件实现，代码如下：
rnd.h

#ifndef ___RND_H
#define ___RND_H

class UnitRand{
protected:
	unsigned int	RandKernel;		
	double			RandMax;		
public:
	void		ChangeKernel(unsigned int);		
	double		Urand(void);					
	UnitRand();							
};
class NormRand : public UnitRand{
private:
	int			Norm_f;
	double		Norm_k,
				Norm_q;
public:
	double		Nrand(void);			
	NormRand();							
};
#endif

rnd.cpp

#include "rnd.h"
#include <stdio.h>
#include <math.h>
#include <limits.h>
#include <time.h>

#define DOUBLE_PI (atan(1.0) * 4.0)

UnitRand::UnitRand(){
	RandKernel = (unsigned int)time(NULL);
	RandMax = (double)UINT_MAX+1.0;				
}

void UnitRand::ChangeKernel(unsigned int NewKernel){
	RandKernel = NewKernel;
}

double UnitRand::Urand(void){
	RandKernel *= 0x5D21DB81U;	
	RandKernel++;				
	return((double)RandKernel/RandMax);
}

NormRand::NormRand() : UnitRand(){
	Norm_f = 0;
}

double NormRand::Nrand(void){
	if( Norm_f ){
		Norm_f = 0;
		return( Norm_k*sin(Norm_q) );
	}
	Norm_f = 1;
	Norm_k = sqrt(-2.0*log(1.0-Urand()));
	Norm_q = 2*DOUBLE_PI*Urand();
	return( Norm_k*cos(Norm_q) );
}

main.cpp

#include<stdio.h>
#include<math.h>
#include<D:\DOCUMENT\T1\Project2\rnd.h>
#include<stdlib.h>

int main()
{
	NormRand sig;
	sig.ChangeKernel(2);
	int x = 0, i = 0;
	for (x = 0; x < 256; ++x)
	{
		double a = sig.Nrand();
		printf("%f\n", a);
	}
}

结果使用matlab画图：
在这里插入图片描述

t1x=xlsread('noise.xlsx');
t1 = linspace(0,256,256);
y1=t1x(:,1);
 plot(t1,y1);
xlabel('Time');
ylabel('Power');
legend('noise');
set(0,'defaultfigurecolor','w')