Circle waves

Special Interest Groups Audio Processing
1

So i’ve seen square, triangle, and sine, but I was thinking is there such thing as a circle wave? I realized one half of a sine wave cycle is not a semi-circle, and I am wondering if there is a way to generate a “circle” wave? In a sense like a square wave, where one half of the circle goes on the positive, and then the other half goes to the negative voltage.

2

Circles have a problem because part of the wave goes backwards, from right to left. The timeline never goes backwards. It’s always now to the future, left to right.

There are scopes and waveforms that don’t have “time” in them, like audio vectorscopes and phasescopes. Those can totally generate a circle.
https://www.google.com/search?q=vectorscope+out+of+phase&tbm=isch&source=iu&imgil=hbePXTg04R_SwM%253A%253Bhttps%253A%252F%252Fencrypted-tbn3.gstatic.com%252Fimages%253Fq%253Dtbn%253AANd9GcRqRFzubCHR32a1-MrC3hURMfs-EniUSfgvkGTDqNfnGD7tMfQI%253B245%253B178%253BH7r4Mj1Kg1lYmM%253Bhttp%25253A%25252F%25252Fwww.enosoft.net%25252Fproducts%25252Fenodvproc%25252Fhelp%25252Fhtm%25252F_audioprocamp.htm&sa=X&ei=zVqqUouOGcKdqQGrhYH4Ag&ved=0CDsQ9QEwBA&biw=1800&bih=959#facrc=_&imgdii=_&imgrc=6jLITgqJ99veLM%3A%3B0-9EShOKo6MmjM%3Bhttp%253A%252F%252Fmbhs.edu%252F~jeglick%252FImages%252FTV%252FShapes.jpg%3Bhttp%253A%252F%252Fmbhs.edu%252F~jeglick%252FTV.html%3B3200%3B1104

Koz

3

You mean a semi-circle above the centre line, followed by a semi-circle below the centre line, followed by a semi-circle above the centre line… ?
Yes that is possible, but it does not sound particularly good :slight_smile:
It’s very late here so I’ll have to come back to this tomorrow with a way to produce such a waveform.
cul8r.

4

This is what I mean

5

… it’s not possible to make them “exact” semi-circles because the start and end of the semi-circle should be vertical (rising instantaneously), but you can get very close.

6

Thats same for square waves correct?

7

Just seen your new post - that’s what I thought you meant :wink: Yes you can get very close to that, but it’s too late here for me to work out the details. I’ll leave this page open so that I don’t forget :slight_smile:

8

Yes.

9

I’ve not finished my cup of tea yet, so here you go - select part of an audio track, open the Nyquist Prompt from the Effect menu, paste this code into the Nyquist Prompt text box and click OK.

(defun c-tone (hz g)
  (let ((c-array (make-array 2048)))
    (dotimes (i 2048)
      (setq x (- 1 (/ i 1024.0)))
      (setf (aref c-array i) (sqrt (- 1 (* x x)))))
    (setf positive (snd-from-array 0 1024 c-array))
    (setf negative (mult -1 positive))
    (setf *c-table* 
      (list (seq positive negative) (hz-to-step 1.0) t))
    (mult g (osc (hz-to-step (* 4.0 hz)) 1 *c-table*))))

(c-tone 440 0.8)
10

I’ve moved this to “Audio Processing”.


Gale

11

Thanks so much steve, I really kinda like this wave, its not as harsh like a square wave, but it isn’t as pure as a sine wave, just in the goldylox

12

Koz recently pointed out to me that something similar can be achieved using the “leveller”…
upper trace is leveller on ''heaviest'' applied x3 to sine wave.png
Which could be even nearer “goldylox”.