Matlab中如何使用fdattool

fdatool设置，在matlab输入fdatool

可以保存为函数

文件名称为fir1，生成的m文件内容为

function Hd = fir1

%FIR1 Returns a discrete-time filter object.

 

% MATLAB Code

% Generated by MATLAB(R) 9.0 and the Signal Processing Toolbox 7.2.

% Generated on: 16-Nov-2018 15:57:29

 

% Equiripple Lowpass filter designed using the FIRPM function.

 

% All frequency values are in MHz.

Fs = 90;  % Sampling Frequency

 

Fpass = 1;                 % Passband Frequency

Fstop = 12;                % Stopband Frequency

Dpass = 0.0057563991496;   % Passband Ripple

Dstop = 3.1622776602e-06;  % Stopband Attenuation

dens  = 20;                % Density Factor

 

% Calculate the order from the parameters using FIRPMORD.

[N, Fo, Ao, W] = firpmord([Fpass, Fstop]/(Fs/2), [1 0], [Dpass, Dstop]);

 

% Calculate the coefficients using the FIRPM function.

b  = firpm(N, Fo, Ao, W, {dens});

Hd = dfilt.dffir(b);

 

% [EOF]

 

2、matlab验证

 

fs=90e6 ;

N=4096;

n= 0:N-1;

t=n/fs;

f1=41.4e6;

f2=41.45e6;

A=2e15;

X=A*cos(2*pi*f1*t);

Y=A*cos(2*pi*f2*t);

figure(1);

plot(X);

figure(2);

plot(Y);

M=X.*Y;

figure(3);

plot(M)

Hd=fir2;

output = filter(Hd,M);

figure(4);

plot(output)

1. 仿真结果

如果只是将采样率设置为为100M，仿真结果,可以看出结果很平滑。

如果将混频的频率换为10.5M和10M,仿真结果为，结果也很光滑。