114 lines
3.1 KiB
Matlab
114 lines
3.1 KiB
Matlab
clear all
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close all
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clc
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% Modify the desired frequency foir the whole code here
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desired_freq = 4000;
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% Read and Set up coeficient
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[y, fs] = audioread("sound/modulator22.wav");
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decrease_coef = round(fs/desired_freq);
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% Modify Signal with downsample
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% Only keeps one sample out of decrease_coef
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down_y = downsample(y,decrease_coef);
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down_fs = fs/decrease_coef;
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audiowrite("sound/down_output.wav", down_y, down_fs);
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% Plot Down Modified
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plot(0:1/down_fs:(length(down_y)-1)/down_fs,down_y);
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xlabel("Time (s)");
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ylabel("Amplitude");
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title("Downsample Sound Amplitude Over Time");
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% Modify Signal with decimate
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% Only keeps one sample out of decrease_coef
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deci_y = decimate(y,decrease_coef);
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deci_fs = fs/decrease_coef;
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audiowrite("sound/deci_output.wav", deci_y, deci_fs);
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% Plot Down Modified
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figure;
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plot(0:1/deci_fs:(length(deci_y)-1)/deci_fs,deci_y);
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xlabel("Time (s)");
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ylabel("Amplitude");
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title("Decimate Sound Amplitude Over Time");
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% Filter Signal with FIR filter
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order = 30;
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cutoff_freq = 1000; % in Hz
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fir_b = fir1(order, cutoff_freq/(fs/2));
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% Show Filter
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figure
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freqz(fir_b)
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% Apply filter
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fir_y = filter(fir_b, 1, y);
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audiowrite("sound/fir_output.wav", fir_y, fs);
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% Plot Down Modified
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figure;
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plot(0:1/fs:(length(fir_y)-1)/fs,fir_y);
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xlabel("Time (s)");
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ylabel("Amplitude");
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title("FIR Filter Sound Amplitude Over Time");
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% Filter Signal with Butter filter
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order = 8;
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cutoff_freq = 1000; % in Hz
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[b, a] = butter(order, cutoff_freq/(fs/2), 'low');
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% Show Filter
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figure
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freqz(b)
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% Apply filter
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butt_y = filter(b, a, y);
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audiowrite("sound/butt_output.wav", butt_y, fs);
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% Plot Down Modified
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figure;
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plot(0:1/fs:(length(butt_y)-1)/fs,butt_y);
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xlabel("Time (s)");
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ylabel("Amplitude");
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title("Butter Filter Sound Amplitude Over Time");
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% Test FIR Filter Stability
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% Find the transfer function
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H = tf(fir_b, 1);
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% Get the poles of the transfer function
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poles = pole(H);
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% Check if all poles are inside the unit circle
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if all(abs(poles) < 1)
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disp('The FIR filter is stable');
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else
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disp('The FIR filter is unstable');
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end
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% Test Butter Filter Stability
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% Find the transfer function
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H = tf(b, a);
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% Get the poles of the transfer function
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poles = pole(H);
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% Check if all poles are inside the unit circle
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if all(abs(poles) < 1)
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disp('The Butter filter is stable');
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else
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disp('The Butter filter is unstable');
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end
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% Modify Signal with downsample
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% Only keeps one sample out of decrease_coef
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down_fir_y = downsample(fir_y,decrease_coef);
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down_fir_fs = fs/decrease_coef;
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audiowrite("sound/down_fir_output.wav", down_fir_y, down_fir_fs);
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% Plot Down Modified
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figure
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plot(0:1/down_fir_fs:(length(down_fir_y)-1)/down_fir_fs,down_fir_y);
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xlabel("Time (s)");
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ylabel("Amplitude");
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title("Downsample FIR Sound Amplitude Over Time");
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% Modify Signal with downsample
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% Only keeps one sample out of decrease_coef
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down_butt_y = downsample(butt_y,decrease_coef);
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down_butt_fs = fs/decrease_coef;
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audiowrite("sound/down_butt_output.wav", down_butt_y, down_butt_fs);
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% Plot Down Modified
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figure
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plot(0:1/down_butt_fs:(length(down_butt_y)-1)/down_butt_fs,down_butt_y);
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xlabel("Time (s)");
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ylabel("Amplitude");
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title("Downsample Butter Sound Amplitude Over Time"); |