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| 1 | −//------------------------------------------------------------------------------ | |
| 2 | −// Pulse Width Modulation | |
| 3 | −// name: pulse.ck | |
| 4 | −// desc: Basic demo of the PulseOsc UGen | |
| 5 | −// | |
| 6 | −// details: | |
| 7 | −// This UGen defines an oscillator that uses Pulse Width Modulation (PWM), a | |
| 8 | −// process that allows for the control of the width of output pulses while | |
| 9 | −// keeping the frequency constant. The on/off ratio of the signal is called the | |
| 10 | −// "duty cycle". A pulse wave may be thought of as a square wave with adjustable | |
| 11 | −// time between cycles. A square wave has a duty cycle of 50% -- alternating | |
| 12 | −// between "on" and "off" in equal proportions. A duty cycle of 75% would mean | |
| 13 | −// the pulse signal is "on" three times as long as it is "off" in one cycle. | |
| 14 | −// The PulseOsc UGen can be used to create sound, or to control other signals! | |
| 15 | −// | |
| 16 | −// Alex Han, Spring 2023 | |
| 17 | −//------------------------------------------------------------------------------ | |
| 18 | − | |
| 19 | −// Setting up | |
| 20 | −PulseOsc pulse => dac; | |
| 21 | − | |
| 22 | −pulse.gain(.2); | |
| 23 | −pulse.freq(440); | |
| 24 | − | |
| 25 | −// The key characteristic of PulseOsc is the ability to set the pulse width (i.e. duty cycle) | |
| 26 | −// When the pulse wave is used to create sound, varying the duty cycle affects the timbre. | |
| 27 | −// This demo shows how the timbre changes significantly with small changes to the pulse width: | |
| 28 | − | |
| 29 | −while(true) | |
| 30 | −{ | |
| 31 | − for(int i; i < 20; i++) | |
| 32 | − { | |
| 33 | − pulse.width(.05 * i); // .width() takes a float from 0.0 to 1.0 | |
| 34 | − chout <= "current duty cycle: " <= pulse.width(); | |
| 35 | − if(pulse.width() == .5) {chout <= " <- this is just a square wave!";} | |
| 36 | − chout <= IO.newline(); | |
| 37 | − 1::second => now; | |
| 38 | − } | |
| 39 | −} | |
| 1 | +//------------------------------------------------------------------------------ | |
| 2 | +// name: pulse.ck | |
| 3 | +// desc: basic demo using PulseOsc UGen to do pulse width modulation | |
| 4 | +// | |
| 5 | +// This UGen defines an oscillator that uses Pulse Width Modulation (PWM), a | |
| 6 | +// process that allows for the control of the width of output pulses while | |
| 7 | +// keeping the frequency constant. The on/off ratio of the signal is called the | |
| 8 | +// "duty cycle". A pulse wave may be thought of as a square wave with adjustable | |
| 9 | +// time between cycles. A square wave has a duty cycle of 50% -- alternating | |
| 10 | +// between "on" and "off" in equal proportions. A duty cycle of 75% would mean | |
| 11 | +// the pulse signal is "on" three times as long as it is "off" in one cycle. | |
| 12 | +// The PulseOsc UGen can be used to create sound, or to control other signals! | |
| 13 | +// | |
| 14 | +// author: Alex Han | |
| 15 | +// date: Spring 2023 | |
| 16 | +//------------------------------------------------------------------------------ | |
| 17 | + | |
| 18 | +// connect | |
| 19 | +PulseOsc pulse => dac; | |
| 20 | +// set gain | |
| 21 | +pulse.gain( .2 ); | |
| 22 | +// set frequency | |
| 23 | +pulse.freq( 110 ); | |
| 24 | + | |
| 25 | +// The key characteristic of PulseOsc is the ability to set the pulse width | |
| 26 | +// (i.e. duty cycle). When the pulse wave is used to create sound, varying | |
| 27 | +// the duty cycle affects the timbre. This demo shows how the timbre changes | |
| 28 | +// significantly with small changes to the pulse width. | |
| 29 | + | |
| 30 | +// time loop | |
| 31 | +while( true ) | |
| 32 | +{ | |
| 33 | + for( int i; i < 20; i++ ) | |
| 34 | + { | |
| 35 | + // .width() takes a float from 0.0 to 1.0 | |
| 36 | + pulse.width( .05 * i ); | |
| 37 | ||
| 38 | + chout <= "current duty cycle: " <= pulse.width(); | |
| 39 | + // floating point equality | |
| 40 | + if( Math.equal( pulse.width(), .5) ) | |
| 41 | + {chout <= " <- this is just a square wave!";} | |
| 42 | + // newline | |
| 43 | + chout <= IO.newline(); | |
| 44 | + // next time step | |
| 45 | + .5::second => now; | |
| 46 | + } | |
| 47 | +} | |
| 48 | + | |
| 49 | +// for more PWM fun... | |
| 50 | +// 1) smoothly vary the pulse width (using a small time scale) | |
| 51 | +// 2) filter the sound (e.g., with LPF) | |