37 lines
1.1 KiB
Matlab
37 lines
1.1 KiB
Matlab
function x = lfo_sawtooth(amplitude, frequency, phase, fs, duration, input)
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% LFO_SAWTOOTH: modulates an input matrix to a sawtooth parameter
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% CONTRIBUTORS:
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% Ben Zhang: Function Author
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% DOCUMENTATION:
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% frequency is below 20Hz for people to hear the sound
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% fs and duration should be same as input
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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 lfo, which will be used to modulate the input
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lfo = zeros(1, n);
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period = 1 / frequency; % period of the wave
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slope = 2 * amplitude / period; % the incline slope from start to amplitude
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% populate lfo 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); % Progression through cycle
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%part before the straght vertical line
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if(st < period /2)
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lfo(i) = amplitude * slope;
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%part after the straght vertical line
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else
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lfo(i) = amplitude * (slope - 1);
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end
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% modulate input
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x = lfo .* input;
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end |