Sine wave frequency

A sinewave could only have a single frequency if it was on forever. The switching envelope will otherwise interact with the sinewave itself.

Which is what windowing is all about.

--
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The simple answer is that in popular usage a sine wave is only a single frequency.

But in the real world there is always noise riding on that sine wave, and possibly other sine waves of smaller amplitude. So if you look at your sine wave on a spectrum analyzer, you will find that the peak is not a spike, such as you would see in a purely mathematical Fourier transform, but is spread out over some frequency range.

You would also see that there are harmonics present. That is to say, there are components at 2x, or 3x or some higher integer multiple of the fundamental sine wave frequency.

What made you think to ask this question here instead of, say, sci.electronics.basic?

--Mac

True enough. And even if the sine wave did go on forever, you couldn't measure its spectrum on a spectrum analyzer unless the spectrum analyzer existed forever, and waited until after the end of time to display its result.

But the simple answer is still "Yes, a sine wave is a single frequency." ;-)

--Mac

Which people are you talking about? Maybe there are some posts which have not appeared on my server yet?

No, I don't see anyone who seems to be forgetting that.

--Mac

"thejim"

** A single frequency is a sine wave AND a sinewave is a single frequency.

Look up " simple harmonic motion " .

.......... Phil

People here seem to be forgetting it's a *pure* sine wave that constitutes a single frequency. Any form of ' irregular sine wave' will contain components of other frequencies and they may not be apparent from visual examination of the wave on an oscilloscope. Their presence undeniable, nevertheless.

--

"What is now proved was once only imagin\'d" - William Blake

Digital communication engineers prefer viewing Sine waves and all periodic functions in the frequency domain , which actually implies analyzing their Fourier transforms. Accordingly you can view a Sine wave as the sum of an infinite number of sinusoids having frequency components which are integral multiples of the fundamental frequency.

"Go easy on the whisky"

theJackal

ha ha You answer to the Op that that he needs to check up Simple Harmonic motion to understand a Sine wave and now this . oh help my soul! You need basic education man ... The "average" engineer knows what Monsier Joseph Fourier discovered more then 200 years ago Sine (w*t) = a + (sum of ( bn* Cos n *w* t + phi (n)) The addition is carried over for n that varies from 1 to infinity.

Phil "Go easy on the whisky"

theJackal

"theJackal"

** Huh ??

Better lay off them hallucinogenics - mate.

........ Phil

Go change your diapers.

The two most common elements in the universe are Hydrogen and stupidity.

Harlan Ellison

"Go easy on the whisky"

theJackal

Keep panting in your bottomless pit wannabe engineer.

"I actually prefer thugs to fools because they sometimes take a rest"

"Go easy on the whisky"

theJackal

" The Jackass "

"Phil Allison"

** You are a schizo, f****ng IDIOT - Piss Off .!!!!!!!!!!!!

** Absoulute rubbish.

A pure sine wave is a SINGLE frequency.

........ Phil

"theJackal"

** = the wog Jackass.

Must be one of them wannabe terrorist imbeciles.

........ Phil

"theJackal"

** Fucking wog psycho.

......... Phil