[chuck-users] phase modulation and hard sync?

Jean Menezes da Rocha jean at menezesdarocha.info
Sun Jun 4 03:16:37 EDT 2017


I have translated a PD patch (see the last graph on this page
<http://pd-tutorial.com/english/ch03s06.html>) and it is modulating AND
responding to frequency changes. See if this does the trick for you
(doesn't sound exactly like your SC code, but I think some fiddling with
modulation index can be useful):

Step imp; // now I am using an impulse to generate sound after calculating
stuff from phasor/sinosc
Phasor carrier; // Miller said to do so ;)
SinOsc modul; // a phasor as carrier, a sinosc as modulator
Gain g; // this object serves only to sum the signals
1 => g.op; // op number 1 is sum.

400 => carrier.freq;
201 => modul.freq;
1 => float ind => modul.gain; // so, modul. signal * index + carrier signal.

imp => dac; // impulse is actually generating sound
carrier => g => blackhole; // both generators go through a Gain object an
then to the blackhole
modul => g; // so that they only lend data to the Impulse generator

while ( true ) { // this loop includes a timed function only to show that
this stuff responds to changes into carrier's frequency
    now + 1::second => time later;
    while (now < later) {
        Math.cos(g.last()) => imp.next; // i am running this through a
Cosine function since Phasor is a ramp (let's smooth that)
        1::samp => now;
    if ( maybe ) 20 + carrier.freq() => carrier.freq;
    else -30 + carrier.freq() => carrier.freq;

Please notice that Miller Puckette's approach includes using the phasor as
*carrier* and sinosc as *modulator*, so that we can separate phase
treatment and wave generation (phasor + cos). I am using an Impulse
generator in order to be allowed to pass the resulting signal through the
cosine function before sending it to DAC.

Keep trying...

Em dom, 4 de jun de 2017 às 03:34, Alexandre Torres Porres <porres at gmail.com>

> 2017-06-04 2:35 GMT-03:00 Alexandre Torres Porres <porres at gmail.com>:
>> It's not easy to explain, but you found the magic number/formula that
>> makes Frequency modulation sound like Phase Modulation.
> Actually, I shouldn't have said this, I don't wanna give you the idea it
> comes down to this, but there are just too many details I didn't want get
> into, sorry. What I can say is that you got pretty close, not 100% there
> yet, and that is not as simple as just doing this every time, it gets more
> complicated.
> Sorry again for not getting into the math and everything. What I'd like to
> add is that people use phase modulation instead of trying to replicate it
> via frequency modulation cause it's just more convenient to do directly via
> phase modulation if you want it to behave like that.
> cheers
> --
Jean Menezes da Rocha
Doutorando em Música pela Universidade Federal da Bahia
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