[sdiy] They aren't sawtooths, they're ramps

[Antti Huovilainen]

On Mon, 2 Nov 2009, Electronic Battle wrote:

>> Sawtooth - sharp transition  from low to high then falls linearly back to 
>> low. repeat.
>> Ramp - linear rise from low to high, sharp transition high to low. repeat.

Having done a fair bit of signal processing, I've never seen sawtooth/ramp 
being treated as separate cases. "Ramp" is usually followed by 
clarification of whether an up- or downgoing ramp is used. There is no 
difference as long as we're dealing with linear or symmetrically nonlinear 
systems.

As for exponential ramp, I've never seen that used without specifically 
mentioning the ramp is exponential. The reset point makes a huge 
difference afterall, so generic exponential ramp is almost meaningless.

> It would be interesting to note the harmonic structure of either. I 
> don't know enough about Fourier to be able to analyse it myself; 
> however, it is still the case that they wil be different but whether the 
> *audible* difference is noteworthy remains to be seen!

I doubt the difference is really audible. The spectrum falls at roughly 
6dB/oct for both and neither has prominent spectral peaks or dips. Ear 
just isn't very sensitive to small smooth changes in spectrum.
I'll try to get around to doing an analysis in matlab later today.

Antti

"No boom today. Boom tomorrow. There's always a boom tomorrow"
   -- Lt. Cmdr. Ivanova