Finish lab report up to Task 2B

Signed-off-by: Warrick Lo <warrick.s.z.lo@gmail.com>

1 files changed, 53 insertions, 0 deletions

diff --git a/matlab/specan.m b/matlab/specan.m
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+function specan(filename)
+	% Spectrum analyser
+	%
+	% Analyse and plot the frequency spectrum of a waveform
+	% given by a tab-separated value (TSV) file.
+	%
+	% The following column headers for the TSV are assumed:
+	% time, v1, v2, v3, i1, i2, i3
+	%
+	% Time measurements are assumed to be in milliseconds.
+	% All voltages and currents are assumed to be given
+	% in Volts and Amperes, respectively.
+
+	data = readtable(filename, FileType="text", Delimiter="\t");
+
+	L = length(data.time);
+	% Assumes data is sampled at regular intervals.
+	T = 1e-3*(data.time(end)-data.time(1))/(L-1);
+	fs = 1/T;
+	% Frequency axis for plotting.
+	f = fs/L*(0:L-1);
+
+	Y1 = abs(fft(data.v1)/L);
+	Y2 = abs(fft(data.v2)/L);
+	Y3 = abs(fft(data.v3)/L);
+	Y4 = abs(fft(data.i1)/L);
+	Y5 = abs(fft(data.i2)/L);
+	Y6 = abs(fft(data.i3)/L);
+
+	figure(1);
+
+	subplot(2, 1, 1);
+	hold on;
+	plot(f, Y1, "r", LineWidth=2);
+	plot(f, Y2, "g", LineWidth=2);
+	plot(f, Y3, "b", LineWidth=2);
+	title("Frequency Spectrum of Voltage Measurements");
+	xlim([0 1e3]);
+	xlabel("Frequency, $f$ (Hz)", Interpreter="latex");
+	ylabel("$\left|\mathcal{F}(V)\right|$ (V)", Interpreter="latex");
+	legend("V_1", "V_2", "V_3");
+
+	subplot(2, 1, 2);
+	hold on;
+	plot(f, Y4, "r", LineWidth=2);
+	plot(f, Y5, "g", LineWidth=2);
+	plot(f, Y6, "b", LineWidth=2);
+	title("Frequency Spectrum of Current Measurements");
+	xlim([0 1e3]);
+	xlabel("Frequency, $f$ (Hz)", Interpreter="latex");
+	ylabel("$\left|\mathcal{F}(I)\right|$ (A)", Interpreter="latex");
+	legend("I_1", "I_2", "I_3");
+end
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