43 lines
1.5 KiB
Matlab
43 lines
1.5 KiB
Matlab
function x = generate_heartbeat(amplitude, frequency, phase, fs, duration, duty)
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% GENERATE_SINE: returns a matrix of sampled heart monitor wave
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% CONTRIBUTORS:
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% Alex Nguyen: Original Author
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% Conner Hsu: Reviewed Code and Assisted in polishing
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% DOCUMENTATION:
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% phase shift is in number of periods
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% fs is the sampling frequency: how many sample points per second
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% duration is time in seconds
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% duty cycle should be a number between 0 and 1.
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% duty of 0 or less would return -amplitude for all sample points
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% duty of 0.25 would return +amplitude for first quarter of each cycle
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% then return -amplitude for the remaining three-fourths
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% duty of 1 would return all +amplitude
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% initialize local variables from input arguments
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n = fs * duration; % number of samples (length of matrix)
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dt = 1 / fs; % sampling period: time between two sample points
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% initialize a one dimensional zero matrix to be populated
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x = zeros(1, n);
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% populate the matrix
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for i = 1:n
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t = i * dt; % time at the i'th sample
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st = mod(frequency * t - phase, 1);
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if (duty-0.25 < st && st < duty)
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slope = amplitude / duty;
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intercept = -0.5 * amplitude;
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x(i) = slope * st + intercept;
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elseif (duty < st && st < duty+0.25)
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slope = amplitude / duty;
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intercept = -amplitude;
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x(i) = slope * st + (1.5 * intercept);
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else
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x(i) = 0;
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end
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end |