Waveform plot for sine wave

Help for Audacity on Windows.
Forum rules
ImageThis forum is for Audacity on Windows.
Please state which version of Windows you are using,
and the exact three-section version number of Audacity from "Help menu > About Audacity".


Audacity 1.2.x and 1.3.x are obsolete and no longer supported. If you still have those versions, please upgrade at https://www.audacityteam.org/download/.
The old forums for those versions are now closed, but you can still read the archives of the 1.2.x and 1.3.x forums.
Post Reply
jsbrunner
Posts: 1
Joined: Fri Aug 14, 2020 10:21 pm
Operating System: Windows 10

Waveform plot for sine wave

Post by jsbrunner » Fri Aug 21, 2020 12:32 am

Using Audacity 2.4.2 and Windows 10.

What causes the pretty pattern on constant tone waveform plots(sine wave)? Like the attached screen shot for a 100 Hz tone generated for six seconds?

Jim Brunner
Attachments
100 Hz tone for six seconds.png
100 Hz tone for six seconds.png (130.24 KiB) Viewed 82 times

steve
Site Admin
Posts: 80694
Joined: Sat Dec 01, 2007 11:43 am
Operating System: Linux *buntu

Re: Waveform plot for sine wave

Post by steve » Fri Aug 21, 2020 1:03 am

It's a kind of Moiré pattern caused by the regularly spaced pixels.
9/10 questions are answered in the FREQUENTLY ASKED QUESTIONS (FAQ)

mafg1953
Posts: 199
Joined: Tue Nov 05, 2019 3:49 pm
Operating System: Windows 10

Re: Waveform plot for sine wave

Post by mafg1953 » Fri Aug 21, 2020 1:34 am

Hmmm, I would say it goes even much deeper than that - it comes from the First Principle!

steve
Site Admin
Posts: 80694
Joined: Sat Dec 01, 2007 11:43 am
Operating System: Linux *buntu

Re: Waveform plot for sine wave

Post by steve » Fri Aug 21, 2020 7:57 am

mafg1953 wrote:
Fri Aug 21, 2020 1:34 am
Hmmm, I would say it goes even much deeper than that - it comes from the First Principle!
Wikipedia defines "first principle" as: "a basic proposition or assumption that cannot be deduced from any other proposition or assumption."

Which basic proposition are you referring to? How does that "first principal" apply to the point in question?


PS. It's a kind of Moiré pattern due to the repeating pattern of the waveform "overlaying" the repeating pattern of "dots" (pixels) on the display. It's a form of aliasing, due to undersampling a fine regular pattern.
9/10 questions are answered in the FREQUENTLY ASKED QUESTIONS (FAQ)

mafg1953
Posts: 199
Joined: Tue Nov 05, 2019 3:49 pm
Operating System: Windows 10

Re: Waveform plot for sine wave

Post by mafg1953 » Fri Aug 21, 2020 11:51 am

Steve,
steve wrote:
Fri Aug 21, 2020 7:57 am
Which basic proposition are you referring to? How does that "first principal" apply to the point in question?
I was alluding to the theory of the Fine-tuned Universe where the amount of detail, accuracy, and order necessary for the universe to function is found in everything that exists – even in apparent chaos. And specifically, the order found in math is particularly relevant as it is math that, in this case, is generating the wave forms.

Maybe I was getting too philosophical after my second Manhattan - I was preparing myself to watch some of the DNC.

Mike

Post Reply