square wave harmonic theory (time domain)

It occurs to me that if the square wave were actually created with a bunch of sine wave generators in a black box, with only the final waveform available at the terminals of the box (in this case, though, we're allow to look inside), we could be having the argument in reverse.

Some might say, "No, there isn't a actual square wave present; it's just a mathematical abstraction."

They would be correct since you can never truly make a squarewave. The rise time is never zero.

And you can never truly make a sinewave; the distortion is never zero.

There's always something to quibble about, isn't there?

No, there isn't always something to quibble about. :)

wave

would

You're quibbling about whether there's always something to quibble about? Sheeesh!! (as Winfield might say)

Ok, then.

I said '"Some might say, "No, there isn't a actual square wave present; it's just a mathematical abstraction."'

You said "They would be correct since you can never truly make a squarewave. The rise time is never zero."

In fact it is the mathematical abstraction that is able to achieve a zero rise time. You just have let the "bunch of sine wave generators", be an *infinity* of sine wave generators, which you can do in the abstraction. One of the things about Fourier's series that impressed mathematicians of the time was that it could converge to a discontinuous function.

It would be the real world version with only a "bunch" of sine wave generators that couldn't achieve zero rise time. The mathematical abstraction can do it with no problem. So anybody who said "there isn't a actual square wave present; it's just a mathematical abstraction." wouldn't be saying that because "zero rise time" couldn't be achieved; if they did, they would be incorrect. It is the abstraction that *can* achieve zero rise time.

{.....]

Allow me to point out the smily at the end of the line. It was intended as a joke.

Some people have had their sense of humor surgically removed. :(

Aha! That explains the "sourpuss" consistency amongst Democrats ;-)

...Jim Thompson

And the "Sheesh" was intended to indicate that I got the joke. :-)

But I still wanted to point that the abstract version can have zero rise time.

I thought the forcing function was the oscillator output.

John