MidtermEnd

SignalMidTerm.m

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+pkg load signal;
+
+signal = csvread('unknownsignal.csv');
+#Create a window for the domain we want to study
+domainStart = 100;
+domainEnd = 400;
+
+lengthDomain = domainEnd - domainStart +1;
+#window the signal
+signal_window = zeros(size(signal));
+signal_window(domainStart:domainEnd) = signal(domainStart:domainEnd) .* blackman(lengthDomain)';
+
+#Plot the two raw signals
+figure;
+subplot(1,2,1);
+plot(signal);
+title("Signal");
+xlabel("samples");
+ylabel("Amplitude");
+
+subplot(1,2,2);
+plot(signal_window);
+title("Blackman signal windowing");
+xlabel("samples");
+ylabel("Gain");
+
+#Apply FFT to both signals.
+signalFFT = fft(signal);
+signalFFTwindow = fft(signal_window);
+fs=600;
+F = (0:length(signal)-1)*(fs/length(signal));
+
+figure;
+subplot(1,2,1);
+plot(F,signalFFT);
+title("Signal FFT");
+xlabel("Frequency");
+ylabel("Gain");
+
+subplot(1,2,2);
+plot(F,signalFFTwindow);
+title("Blackman signal FFT");
+xlabel("Frequency");
+ylabel("Gain");
+
+
+order = 50;
+fc = 100;   % cutoff frequency
+h_fir1 = fir1(order, fc/(fs/2));
+
+n = 4;
+Wn = fc/(fs/2);
+[b, a] = butter(n, Wn);
+
+
+% filter the signals
+filtered_signal = filter(h_fir1, 1, signal);
+filtered_windowed_signal = filter(h_fir1, 1, signal_window);
+filtered_signal_butter = filter(b, a, signal);
+filtered_windowed_signal_butter = filter(b, a, signal_window);
+
+% plot the signals using subplots
+t = linspace(0, length(signal)/fs, length(signal));
+t_window = linspace(0, length(signal)/fs, length(signal));
+
+subplot(2,2,1);
+plot(t, signal);
+title('Original Signal');
+
+subplot(2,2,2);
+plot(t_window, signal_window);
+title('Windowed Signal');
+
+subplot(2,2,3);
+plot(t, filtered_signal);
+title('FIR1 Filtered Signal');
+
+subplot(2,2,4);
+plot(t_window, filtered_windowed_signal);
+title('FIR1 Filtered Windowed Signal');
+
+figure;
+
+subplot(2,2,1);
+plot(t, signal);
+title('Original Signal');
+
+subplot(2,2,2);
+plot(t_window, signal_window);
+title('Windowed Signal');
+
+subplot(2,2,3);
+plot(t, filtered_signal_butter);
+title('Butterworth Filtered Signal');
+
+subplot(2,2,4);
+plot(t_window, filtered_windowed_signal_butter);
+title('Butterworth Filtered Windowed Signal');
+