Software to plot modulation ?

oXo · Joined: Sep 20, 2004 Posts: 36 Location: Paris

Hello,
I 'm searching a software to plot different modulation waveshape, I can do with my synth.
The idea is : all of us know the effect of an sin LFO applied to a picth or other parameters, but when we use more LFO, like a sin LFO + a 25% pulse LFO with a period equal a half of the sine... It 's really more difficult to think of the resulting wave... I'm trying to do the drawing with excel and it works well with simple waveshapes like sin or triangle, but it become difficult with waveshape like stairs...
Any ideas ?

blue hell · Posted: Thu Sep 30, 2004 6:36 am Post subject:

To staircase a signal you'll want to round it or convert it into an integer somehow.

In Pascal I use expressions like Signal := Round( Signal * 256) / 256; (assuming the maximum signal level is 1 and wanting 8 bits resolution = 256 steps).

Another way to go might be to use modulo(), int() and/or frac() functions, I don't know what Excel's possibilities are in this.

Depending upon the signal scale you use things might have to be changed a bit. Like in :

Signal := Round( Signal * ( WantedStepsNum / FullScaleSignal)) / ( WantedStepsNum * FullScaleSignal);

The idea is to scale the signal up in such a way that the wanted number of stairs matches the signal range. Once there you convert the number into an integer (thereby loosing all the fractions and staircasing the thing) and then you scale it back to the original range.

Jan.