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59 lines
1.4 KiB
59 lines
1.4 KiB
clear; clc; close all;
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% 1. 参数
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fs = 10000; % 采样频率 10 kHz
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t_total = 1; % 时间长度 1 s
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f0 = 1000; % 基频 1 kHz
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t = 0:1/fs:t_total-1/fs; % 时间轴
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N = length(t)
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% 2. 基频信号
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x = sin(2*pi*f0*t);
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% 3. 线性系统、非线性系统
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y1 = 2 * x; % 线性
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y2 = x + 0.5*x.^2 + 0.1*x.^3; % 非线性
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% 4. 时域图
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figure('Color','w');
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idx = t <= 0.01; % 按要求取前10ms
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subplot(2,1,1);
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plot(t(idx)*1000, x(idx), 'k'); hold on;
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plot(t(idx)*1000, y1(idx), 'b');
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plot(t(idx)*1000, y2(idx), 'r');
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xlabel('时间/ms');
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ylabel('幅度');
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title('时域');
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legend('x(t)','y1(t)','y2(t)');
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grid on;
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% 5. FFT
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f = (0:N-1)*fs/N;
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X = abs(fft(x, N)) / length(x);
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Y1 = abs(fft(y1, N)) / length(y1);
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Y2 = abs(fft(y2, N)) / length(y2);
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% 只画正频率
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X = X(1:N/2+1);
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Y1 = Y1(1:N/2+1);
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Y2 = Y2(1:N/2+1);
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f = f(1:N/2+1);
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subplot(2,1,2);
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plot(f, Y1, 'b', 'LineWidth',1.5); hold on;
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plot(f, Y2, 'r', 'LineWidth',1.5);
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xlim([0, 4500]);
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xlabel('频率/Hz');
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ylabel('幅度');
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title('频域单边幅度谱');
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legend('线性','非线性');
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% 6. 谐波幅值输出
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f1_idx = find(f>=1000,1);
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f2_idx = find(f>=2000,1);
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f3_idx = find(f>=3000,1);
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fprintf('基频 1kHz 幅值：%.4f\n', Y2(f1_idx));
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fprintf('二次谐波 2kHz 幅值：%.4f\n', Y2(f2_idx));
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fprintf('三次谐波 3kHz 幅值：%.4f\n', Y2(f3_idx)); |