求设计一个带通滤波器到matlab程序

%

用切比雪夫最佳一致逼近设计线性相位FIR带通滤波器；

%信号为0.5hz,

0.9hz,

1.1hz和1.5hz的正统信号叠加组成

%通带为[0.9,1.1]

%频谱分辨率与信号实际长度N成正比

clear

all

f1=0.5f2=0.9f3=1.1f4=1.5t=0:1203N=length(t)fs=10M=512

x1=sin(2*pi*(f1/fs)*t)+sin(2*pi*(f2/fs)*t)+sin(2*pi*(f3/fs)*t)+sin(2*pi*(f4/fs)*t)

figure(1)

subplot(211)plot(t,x1)title('原信号')

y=fft(x1)

f=(0:1/N:1/2-1/N)*fs

subplot(212)plot(f,abs(y(1:N/2)))gridxlabel('hz')%处理前频谱

wc1=2*f2/fswc2=2*f3/fswc3=2*f4/fs%归一化角频率，用于下面的f1

f1=[0

wc1-0.05

wc1

wc2

wc2+0.05

1]

A=[0

0

1

1

0

0]%设置带通或带阻，1为带通，0为带阻

weigh=[1

1

1

]%设置通带和阻带的权重

b=remez(60,f1,A,weigh)%传函分子

h1=freqz(b,1,M)%幅频特性

figure(2)

f=(0:1/M:1-1/M)*fs/2

subplot(211)plot(f,abs(h1))gridtitle('带通')

x2=filter(b,1,x1)

S1=fft(x2)

f=(0:1/N:1/2-1/N)*fs

subplot(212)plot(f,abs(S1(1:N/2)))gridxlabel('hz')%处理后频谱

short h[], short y[])

{

int i, j, sum for (j = 0j <100j++) {

sum = 0

for (i = 0i <32i++)

sum += x[i+j] * h[i]

y[j] = sum >>15

}

}

2

void fir(short x[], short h[], short y[])

{

int i, j, sum0, sum1

short x0,x1,h0,h1 for (j = 0j <100j+=2) {

sum0 = 0

sum1 = 0

x0 = x[j]

for (i = 0i <32i+=2){

x1 = x[j+i+1]

h0 = h[i]

sum0 += x0 * h0

sum1 += x1 * h0

x0 = x[j+i+2]

h1 = h[i+1]

sum0 += x1 * h1

sum1 += x0 * h1

}

y[j] = sum0 >>15

y[j+1] = sum1 >>15

}

}

3

void fir(short x[], short h[], short y[])

{

int i, j, sum0, sum1

short x0,x1,x2,x3,x4,x5,x6,x7,h0,h1,h2,h3,h4,h5,h6,h7 for (j = 0j <100j+=2) {

sum0 = 0

sum1 = 0

x0 = x[j]

for (i = 0i <32i+=8){

x1 = x[j+i+1]

h0 = h[i]

sum0 += x0 * h0

sum1 += x1 * h0

x2 = x[j+i+2]

h1 = h[i+1]

sum0 += x1 * h1

sum1 += x2 * h1

x3 = x[j+i+3]

h2 = h[i+2]

sum0 += x2 * h2

sum1 += x3 * h2

x4 = x[j+i+4]

h3 = h[i+3]

sum0 += x3 * h3

sum1 += x4 * h3

x5 = x[j+i+5]

h4 = h[i+4]

sum0 += x4 * h4

sum1 += x5 * h4

x6 = x[j+i+6]

h5 = h[i+5]

sum0 += x5 * h5

sum1 += x6 * h5

x7 = x[j+i+7]

h6 = h[i+6]

sum0 += x6 * h6

sum1 += x7 * h6

x0 = x[j+i+8]

h7 = h[i+7]

sum0 += x7 * h7

sum1 += x0 * h7

}

y[j] = sum0 >>15

y[j+1] = sum1 >>15

}

}

窗函数设计低通滤波器：

fp=1000

fc=1200

as=100

ap=1

fs=22000

wp=2*fp/fs

wc=2*fc/fs

N=ceil((as-7.95)/(14.36*(wc-wp)/2))+1

beta=0.1102*(as-8.7)

window=Kaiser(N+1,beta)

b=fir1(N,wc,window)

freqz(b,1,512,fs)

高通滤波器：

fs=22000

Wp=2*5000/fs

Ws=2*4800/fs

Ap=1

As=100

N=ceil(8*pi/(Wp-Ws))+1

N=N+mod(N+1,2)+1

Wc=(Wp+Ws)/2/pi

h=fir1(N,Wc,'high')

omega=linspace(0,pi,512)

freqz(h,1,omega)

带通滤波器：

fs=22000

Wp1=2*1200/fs

Wp2=2*3000/fs

Wc1=2*1000/fs

Wc2=2*3200/fs

Ap=1

As=100

W1=(Wp1+Wc1)/2

W2=(Wp2+Wc2)/2

wdth=min((Wp1-Wc1),(Wc2-Wp2))

N=ceil(11*pi/wdth)+1

b = fir1(N,[W1 W2])

freqz(b,1,512,fs)

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