# [chuck-users] phase modulation and hard sync?

mario buoninfante mario.buoninfante at gmail.com
Mon Jun 5 02:35:30 EDT 2017

```hi Alexandre,

last but not the least, the point we're I was lost is that I got
confused cause I achieved the same results.

to summarize (it's more for myself ;) )

with Phasor is PM without it isn't. just it's simple achieve the same
result, cause some scenarios allow that.

It's a tough ground, and I got confused about that. I have to say thank
you, cause it was such a long time I didn't spend time about "musical
math" stuff ;) . and this was a good occasion to do that.

anyway, I hope the Phasor implementation I attached before was useful.
that is correct and seems to be quite simple. ;)

cheers,
Mario

On 04/06/17 22:44, Alexandre Torres Porres wrote:
> 2017-06-04 13:59 GMT-03:00 mario.buoninfante
> <mario.buoninfante at gmail.com <mailto:mario.buoninfante at gmail.com>>:
>
>     Now 2pi is needed only if you deal with a ramp, with a phasor.
>     Cause Phasor*2pi gives you a sine. If you already have a sine
>     there is no need to use 2pi.
>
> Hi, let me try to be clearer. Phasor * 2pi going through a sine
> function gives you a sine wave. SinOsc can also be drive by a Phasor.
> Such as this.
>
> Phasorp => SinOscosc => dac;
>
> 440=>p.freq;
>
> 1=>osc.sync;
>
> 4::second=> now;
>
>
> In this case, you get a sine wave and you don't need to multiply the
> phasor by 2pi, because the input is normalized, from 0-1
>
>
> What I was trying to say is that if you have a modulating index in
> phase modulation, and you want to replicate it in frequency
> modulation, you alsop need to multiply it by 2pi.
>
> I'm not challenging the math or equations, just adding an
> implementation detail in Chuck code. I know I wasn't clear about it,
> sorry. Hope it's clear now.
>
> But my main point was something else. It is true that if you multiply
> the index value by the modulation frequency value, such as in your
> code, you sort of get a similar behaviour than you'd get with phase
> modulation. But there's another detail missing if you're to really
> convert it.
>
> modulation signal needs to also be adjusted. In terms of sine waves,
> if you have the phase signal being modulated by a sine wave, you need
> to modulate the frequency with a cosine wave.
>
> With other waveforms it gets more complicated. By the way, the rule of
> thumb (multiply the index by the frequency) also changes, that is
> important to note as well.
>
> My main point is just that it's just best to implement via phase
> modulation, if that's the behaviour you want.
>
> cheers

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.cs.princeton.edu/pipermail/chuck-users/attachments/20170605/60dc9165/attachment.html>
```