% 清除工作空间变量，关闭所有图形界面
clear;
close all;% 读取数据
[a, b] = xlsread('s10_walk.xlsx');% 采样频率
fs = 500;% 选择PPG信号和ECG信号
PPG = a(:, 2);
ECG = a(:, end);% 创建时间轴
t = (1:length(PPG)) / fs;% 绘制PPG和ECG的时域图
figure
subplot(2,1,1)
plot(t, PPG)
title('PPG信号的时域图')
xlabel('时间 (秒)')
ylabel('幅值')
axis tightsubplot(2,1,2)
plot(t, ECG)
title('ECG信号的时域图')
xlabel('时间 (秒)')
ylabel('幅值')
axis tight% 计算并绘制PPG和ECG的频域图
% 快速傅里叶变换
N = length(PPG);
f = (0:N-1)*(fs/N); % 频率范围
PPG_FFT = abs(fft(PPG));
ECG_FFT = abs(fft(ECG));% 限制绘图频率范围从0.1Hz到5Hz
f_limit = f(f >= 0.1 & f <= 5);
PPG_FFT = PPG_FFT(f >= 0.1 & f <= 5);
ECG_FFT = ECG_FFT(f >= 0.1 & f <= 5);figure
subplot(2,1,1)
plot(f_limit, PPG_FFT)
title('PPG信号的频域图')
xlabel('频率 (Hz)')
ylabel('幅度')
axis tightsubplot(2,1,2)
plot(f_limit, E