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CA2_Equiripple and Butterworth FIR filters/CA#2_DSP_SahandKhoshdel_810196607/Problem_1.m

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+
+
+% Part 0 : Reading the noisy sound and playing it 
+
+[noisy_sound,Fs] = audioread('Noisysound.wav');
+%sound(noisy_sound,Fs);
+
+% Part 1 : Plotting the Frequency Spectrum :
+
+noisy_sound_ft = fft(noisy_sound ,length(noisy_sound));
+noisy_sound_fts = fftshift(abs(noisy_sound_ft));
+len=length(noisy_sound);
+Freq_range=Fs*(-len/2:len/2-1)/len;
+
+figure
+plot(Freq_range,noisy_sound_ft);
+title('Fourier transform (Noisy Sound) ');
+xlabel('Frequency (Hz)');
+ylabel('Amplitude ');
+
+figure
+plot(Freq_range,noisy_sound_fts);
+title('Shifted Fourier transform (Noisy Sound) ');
+xlabel('Frequency (Hz)');
+ylabel('Amplitude ');
+
+
+% Part 2 : Designing Band-Stop Filter (Equi-ripple method)
+
+figure
+freqz(BS_ER);
+title('Band-stop Filter (Equi-ripple)');
+xlabel('Frequency');
+ylabel('Amplitude');
+filtered_sound = filter(BS_ER,1,noisy_sound);
+
+
+% Part 3 : Playing the filtered sound
+
+%sound(filtered_sound,Fs);
+audiowrite('NoiseLess.wav',filtered_sound,Fs);
+
+figure
+plot(Freq_range,filtered_sound);
+title('Band-Pass Filtered sound');
+xlabel('Frequency (Hz)');
+ylabel('Amplitude ')
+
+
+% Part 4 : Designing Low-pass 
+
+BS_filtered = audioread('NoiseLess.wav');
+%Playying sound before low-pass 
+
+%sound(BS_filtered,Fs);
+
+%frequency response of LP_filter : 
+figure
+freqz(LP_ER);
+title('Low-pass Filter (Equi-ripple)');
+xlabel('Frequency');
+ylabel('Amplitude');
+
+LP_filtered = filter(LP_ER,1,BS_filtered);
+%Playing sound after low-pass:
+%sound(LP_filtered,Fs);
+audiowrite('NoiseLess_LP.wav',LP_filtered,Fs);
+
+% Comparing signal before and after applying LP filter (time domain)
+figure
+plot((0:len-1)/Fs,filtered_sound)
+hold on
+plot((0:len-1)/Fs,LP_filtered)
+legend('Sound before Low-pass filter','Sound after Low-Pass filter');
+title('Comparing signal before and after applying LP filter (time domain)');
+xlabel('Time');
+ylabel('Amplitude');
+
+
+% Comparing fft-shifted signal before and after applying LP filter (freq domain)
+fftshift_before_LP = abs(fftshift(fft(filtered_sound)));
+fftshift_after_LP = abs(fftshift(fft(LP_filtered)));
+
+figure
+plot(Freq_range,fftshift_before_LP);
+title('FFT-shifted of noiseless signal before LP');
+ylabel('Amplitude');
+xlabel('Frequency');
+
+figure
+plot(Freq_range,fftshift_after_LP);
+title('FFT-shifted of noiseless signal after LP');
+ylabel('Amplitude');
+xlabel('Frequency');
+
+
+% Part 4 : with IIR
+
+%Playying sound before and after high-pass
+%sound(LP_filtered,Fs);
+
+%frequency response of HP_filter : 
+figure
+freqz(HP_BW);
+title('High-pass Filter (Butter-worth)');
+xlabel('Frequency');
+ylabel('Amplitude');
+
+HP_filtered = filter(HP_BW,1,BS_filtered);
+
+%Playing sound after High-pass:
+%sound(HP_filtered,Fs);
+audiowrite('NoiseLess_HP.wav',HP_filtered,Fs);
+
+% Comparing signal before and after applying HP filter (time domain)
+figure
+plot((0:len-1)/Fs,filtered_sound)
+hold on
+plot((0:len-1)/Fs,HP_filtered)
+legend('Sound before High-pass filter','Sound after High-Pass filter');
+title('Comparing signal before and after applying HP filter (time domain)');
+xlabel('Time');
+ylabel('Amplitude');
+
+% Comparing fft-shifted signal before and after applying LP filter (freq domain)
+fftshift_before_HP = abs(fftshift(fft(filtered_sound)));
+fftshift_after_HP = abs(fftshift(fft(HP_filtered)));
+
+figure
+plot(Freq_range,fftshift_before_HP);
+title('FFT-shifted of noiseless signal before HP');
+ylabel('Amplitude');
+xlabel('Frequency');
+
+figure
+plot(Freq_range,fftshift_after_HP);
+title('FFT-shifted of noiseless signal after HP');
+ylabel('Amplitude');
+xlabel('Frequency');

CA2_Equiripple and Butterworth FIR filters/CA#2_DSP_SahandKhoshdel_810196607/Problem_2.m

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+figure
+freqz(SOS_BS_EL);