Support

If you have a problem or need to report a bug please email : support@dsprobotics.com

There are 3 sections to this support area:

DOWNLOADS: access to product manuals, support files and drivers

HELP & INFORMATION: tutorials and example files for learning or finding pre-made modules for your projects

USER FORUMS: meet with other users and exchange ideas, you can also get help and assistance here

NEW REGISTRATIONS - please contact us if you wish to register on the forum

I need a Cycloid

For general discussion related FlowStone

I need a Cycloid

Postby HughBanton » Mon Nov 28, 2022 5:23 pm

Trying to devise something for which I believe I need a cycloid waveform. One of these :

https://upload.wikimedia.org/wikipedia/ ... loid_f.gif

Anyone got a clue about how to generate a thing like that?

H
User avatar
HughBanton
 
Posts: 265
Joined: Sat Apr 12, 2008 3:10 pm
Location: Evesham, Worcestershire

Re: I need a Cycloid

Postby adamszabo » Mon Nov 28, 2022 5:57 pm

you can get a parabola wave which is similar, by multiplying the output of a saw with itself
adamszabo
 
Posts: 657
Joined: Sun Jul 11, 2010 7:21 am

Re: I need a Cycloid

Postby HughBanton » Mon Nov 28, 2022 6:08 pm

Oh yes, so you do, thanks.

Not so strangely .. I had the tools to test this right in front of me, trying to find the answer myself! (But so far failing miserably).

And therefore, you get the whole shape if you multiply a triangle by itself. Bingo. :D

Hugh
User avatar
HughBanton
 
Posts: 265
Joined: Sat Apr 12, 2008 3:10 pm
Location: Evesham, Worcestershire

Re: I need a Cycloid

Postby HughBanton » Mon Nov 28, 2022 6:49 pm

Like so : (Since I just know that everyone's just desperate for a Cycloid too!)

Code: Select all
streamin inc; streamout out;
float count, temp;
//
count += inc;
count -= count & (count>=1); // reset count
temp = count &(count<0.5) + (1-count) & (count>0.5); // to triangle
out = -2*(temp*temp) + 0.5; // to Cycloid (-ish)

So, what am I going to do with it ....

H
User avatar
HughBanton
 
Posts: 265
Joined: Sat Apr 12, 2008 3:10 pm
Location: Evesham, Worcestershire

Re: I need a Cycloid

Postby R&R » Mon Nov 28, 2022 9:44 pm

So, what am I going to do with it ....


DC-adjust for use with rotary speaker... and open a portal unleashing doom-guy? :D

Would be interesting to see the spectral content of an actual cycloid waveform but inverted (alternating?... I don't know what it's called in the digital world... normalized? :) eh... sinusoidal... but, cycloid :lol: ) Damnit I painted myself into a corner...
R&R
 
Posts: 432
Joined: Fri Jul 15, 2022 2:28 pm

Re: I need a Cycloid

Postby martinvicanek » Wed Nov 30, 2022 8:35 am

(Beware! Nerdy stuff ahead!)

A squared saw or triangle (same thing basically) is at best a poor man's cycloid. The cusp shape is not right. Atached is the real deal! ;)
I am not sure if it is much of a practical value because the "right" cusp shape causes some nasty aliasing. Anyway, here it is, have fun! :lol:
Attachments
CycloidOsc.fsm
(15.97 KiB) Downloaded 226 times
User avatar
martinvicanek
 
Posts: 1315
Joined: Sat Jun 22, 2013 8:28 pm

Re: I need a Cycloid

Postby R&R » Wed Nov 30, 2022 12:05 pm

:lol:
R&R
 
Posts: 432
Joined: Fri Jul 15, 2022 2:28 pm

Re: I need a Cycloid

Postby HughBanton » Tue Dec 06, 2022 10:47 am

Fabulous Martin. Somehow we all just knew you'd be the man with the true answer 8-)

Practical? Never stopped me before ...

H
User avatar
HughBanton
 
Posts: 265
Joined: Sat Apr 12, 2008 3:10 pm
Location: Evesham, Worcestershire

Re: I need a Cycloid

Postby HughBanton » Tue Dec 06, 2022 11:30 am

So I should tell you about what my fevered brain has been thinking about .. (apologies for a complete tangent here)

When a real wind instrument is physically blown (that'll include organ pipes, innit..) there's inevitably going to be a 'DC' air-stream, which in the human case, I learn, is around 12m/S. Around 4% of the speed of sound.

So, does it follow then that the oscillating wave emitted at the end of the tube is actually travelling onwards 4% faster than the surrounding air? (And note, the harder the blowing, the greater the velocity differential).

So what happen next, as the wave travels outwards? I'm assuming it somehow slows down to a mean velocity before it reaches our ears.

So next question is, what happens when sound is forced to decelerate .. well we all know the answer to that one!

Is this real / worth investigating, or a total fallacy?

H

(I'll maybe come back to the cycloid bit anon :) )
User avatar
HughBanton
 
Posts: 265
Joined: Sat Apr 12, 2008 3:10 pm
Location: Evesham, Worcestershire

Re: I need a Cycloid

Postby R&R » Tue Dec 06, 2022 2:16 pm

Isn't the speed of sound always the speed of sound? I'm confused... :? But... that's not a rare occurrence :lol:
In other words how fast the pressure differentials (within the audible freq range) can ever propagate through air medium? (at normal altitude / air composition)

Anyone correct me if i'm off at any point...

Low frequencies are pretty much omni directional... and the higher you go, the more dissipation (high freq = low kinetic energy). Since high frequencies are also very directional they are also subject to diffusion. Both high and low frequencies reflect, but they act very differently in that regard. High frequencies reflect almost at angle the higher you go, and low freq acts like a gas... almost accumulates at pressure zones or "nodes". Nodes of course being present at all frequencies but low frequencies often being discussed in acoustics.

I would imagine the airstream itself... causing the oscillations at the pipe opening (or where the standing waves meets the air outside the pipe? is that how it works? :? )... drops of immediately when leaving the pipe? The only moving air is the air traveling between low and hi pressure zones of the wavefront itself?

Why do I imagine Spogg is a guru at this stuff... :D
R&R
 
Posts: 432
Joined: Fri Jul 15, 2022 2:28 pm


Return to General

Who is online

Users browsing this forum: No registered users and 43 guests

cron