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Merge pull request #7 from ltcptgeneral/improve_comments

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Added additional comments for wave generation functions
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Arthur Lu 2021-12-03 20:07:00 -08:00 committed by GitHub
commit 843084257d
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3 changed files with 91 additions and 33 deletions
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33
src/generate_sine.m
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@ -1,15 +1,28 @@
function x = generate_sine(amplitude, frequency, phase, fs, duration, duty)
%GENERATE_SINE:Arthur Lu returns a matrix of sampled sine wave, where the
%phase shift is in number of periods
x = zeros(1, fs * duration);
A = amplitude;
f = frequency;
p = phase;
n = fs * duration;
dt = 1 / fs;
% GENERATE_SINE: returns a matrix of sampled sine wave
% CONTRIBUTORS:
% Arthur Lu: Original author
% Benjamin Liou: refactoring and annotations
% DOCUMENTATION:
% phase shift is in number of periods
% fs is the sampling frequency: how many sample points per second
% duration is time in seconds
% duty does not apply for sinusoids
% initialize local variables from input arguments
n = fs * duration; % number of samples (length of matrix)
dt = 1 / fs; % sampling period: time between two sample points
% initialize a one dimensional zero matrix to be populated
x = zeros(1, n);
% populate the matrix
for i = 1:n
t = i * dt;
x(i) = A * sin(2 * pi * f * t - p);
t = i * dt; % time at the i'th sample
x(i) = amplitude * sin(2 * pi * frequency * t - phase);
end
end

45
src/generate_square.m
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@ -1,19 +1,40 @@
function x = generate_square(amplitude, frequency, phase, fs, duration, duty)
%GENERATE_SINE:Arthur Lu returns a matrix of sampled sine wave, where the
%phase shift is in number of periods
x = zeros(1, fs * duration);
A = amplitude;
f = frequency;
p = phase;
n = fs * duration;
dt = 1 / fs;
% GENERATE_SQUARE: returns a matrix of sampled square wave
% CONTRIBUTORS:
% Arthur Lu: Original author
% Benjamin Liou: refactoring and annotations
% DOCUMENTATION:
% phase shift is in number of periods
% fs is the sampling frequency: how many sample points per second
% duration is time in seconds
% duty cycle should be a number between 0 and 1.
% duty of 0 or less would return -amplitude for all sample points
% duty of 0.25 would return +amplitude for first quarter of each cycle
% then return -amplitude for the remaining three-fourths
% duty of 1 would return all +amplitude
% initialize local variables from input arguments
n = fs * duration; % number of samples (length of matrix)
dt = 1 / fs; % sampling period: time between two sample points
% initialize a one dimensional zero matrix to be populated
x = zeros(1, n);
% populate the matrix
for i = 1:n
t = i * dt;
st = mod(f * t - p, 1);
t = i * dt; % time at the i'th sample
% periodic ramp from 0 to 1
% progression through a cycle
st = mod(frequency * t - phase, 1);
if(st < duty)
x(i) = A;
x(i) = amplitude;
else
x(i) = -A;
x(i) = -amplitude;
end
end
end

46
src/generate_triangle.m
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@ -1,19 +1,43 @@
function x = generate_triangle(amplitude, frequency, phase, fs, duration, duty)
%GENERATE_SINE:Arthur Lu returns a matrix of sampled sine wave, where the
%phase shift is in number of periods
x = zeros(1, fs * duration);
A = amplitude;
f = frequency;
p = phase;
n = fs * duration;
dt = 1 / fs;
% GENERATE_TRIANGLE: returns a matrix of sampled square wave
% CONTRIBUTORS:
% Arthur Lu: Original author
% Benjamin Liou: refactoring and annotations
% DOCUMENTATION:
% phase shift is in number of periods
% fs is the sampling frequency: how many sample points per second
% duration is time in seconds
% duty cycle should be a number between 0 and 1.
% duty of 0.25 would have positive slope for first quarter of each cycle
% then have negative slope for the remaining three-fourths
% initialize local variables from input arguments
n = fs * duration; % number of samples (length of matrix)
dt = 1 / fs; % sampling period: time between two sample points
% initialize a one dimensional zero matrix to be populated
x = zeros(1, n);
% populate the matrix
for i = 1:n
t = i * dt;
st = mod(f * t - p, 1);
% periodic ramp from 0 to 1
% progression through a cycle
st = mod(frequency * t - phase, 1);
if(st < duty)
x(i) = A*(1/duty * st - 0.5);
slope = amplitude / duty;
intercept = -0.5 * amplitude;
x(i) = slope * st + intercept;
else
x(i) = A*(-(1/(1-duty))*st + (duty/(1-duty)) + 1 - 0.5);
slope = -amplitude / (1 - duty);
intercept = amplitude*( duty/(1-duty) + 0.5);
x(i) = slope * st + intercept;
end
end
end