用matlab写一段SPA滤波函数
时间: 2024-03-13 15:25:51 浏览: 24
function [y] = SPA_filter(x,fs,f0,df,Q)
%SPA_filter Summary of this function goes here
% This function implements a single-pole all-pass (SPA) filter.
% x: input signal
% fs: sampling rate
% f0: center frequency
% df: frequency deviation
% Q: quality factor
% Calculate the filter coefficients
w0 = 2*pi*f0/fs;
w1 = 2*pi*(f0+df)/fs;
w2 = 2*pi*(f0-df)/fs;
a0 = tan(w1/2)-tan(w2/2);
b0 = -cos(w0);
c0 = 1/tan(w1/2)+1/tan(w2/2);
d0 = 1-c0/2;
% Initialize the output signal
y = zeros(size(x));
% Apply the filter to the input signal
for n = 2:length(x)
y(n) = a0*(x(n)+x(n-1))-b0*y(n-1)+c0*x(n)+d0*y(n-1);
end
% Normalize the output signal
y = y/max(abs(y));
end
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用matlab写一段滤波函数
function y = filter_func(x, fc, fs, order, type)
% x: 输入信号
% fc: 截止频率
% fs: 采样频率
% order: 滤波阶数
% type: 滤波类型,可选值为: 'lowpass', 'highpass', 'bandpass', 'bandstop'
% 计算归一化截止频率
wc = 2 * pi * fc / fs;
% 计算滤波系数
switch type
case 'lowpass'
[b, a] = butter(order, wc, 'low');
case 'highpass'
[b, a] = butter(order, wc, 'high');
case 'bandpass'
[b, a] = butter(order, wc, 'bandpass');
case 'bandstop'
[b, a] = butter(order, wc, 'stop');
otherwise
error('不支持的滤波类型');
end
% 使用滤波器对输入信号进行滤波
y = filter(b, a, x);
end
用matlab写一段SG滤波的程序
SG(Savitzky-Golay)滤波是一种平滑信号的方法,可以用于去噪和信号平滑。下面是一个用MATLAB实现SG滤波的例子:
```matlab
function y_filt = sg_filter(x, window_size, order, deriv)
% x: 输入信号
% window_size: 窗口大小
% order: 多项式阶数
% deriv: 求导数的阶数
% 构造系数矩阵
half_size = (window_size - 1)/2;
x_axis = -half_size:half_size;
A = zeros(window_size, order+1);
for i = 0:order
A(:,i+1) = x_axis.^i;
end
% 计算伪逆矩阵
AtA = A' * A;
Aty = A' * x';
coef = AtA \ Aty;
% 计算导数系数
if deriv > 0
coef = coef(end:-1:1);
for i = 1:deriv
coef = polyder(coef);
end
end
% 应用滤波器
y_filt = filtfilt(coef, 1, x);
end
```
使用方法:将上述代码保存为.m文件,并在MATLAB命令行中输入以下命令:
```matlab
y_filt = sg_filter(x, window_size, order, deriv)
```
其中,x为输入信号,window_size为滤波窗口大小,order为多项式阶数,deriv为求导数的阶数。返回值y_filt为滤波后的信号。