# Damped wave harmonics

Discussion in 'Electronic Design' started by Bob Stern, Jun 4, 2007.

1. ### Bob SternGuest

Can anyone tell me if damped waves (ringing), by their nature,
incorporate harmonics of the fundamental frequency?

Bob Stern

2. ### D from BCGuest

I'm no math genius nor do I claim I'm correct but I'll guess
yes..A damped wave "'ping, boing, pong, thump" contains harmonics.
In order for amplitude to change..there must be distortion and
distortion is composed of harmonics and these harmonics are above and
related to the fundamental frequency.
I think everything has harmonics with the exception of a pure
continuous tone..and no signal..

D from BC

3. ### D from BCGuest

oops pure continuous sine wave not tone..
1:22am in BC...zzzzzz
D from BC

4. ### redbellyGuest

No, not harmonics. But it will contain extra frequencies in a narrow
band around the "fundamental". The width of the band is determined by
the decay time, i.e. a longer decay time results in a narrower
frequency band than a shorter decay time.

Harmonics appear when you are dealing with a periodic signal, which
this example isn't.

Regards,

Mark

5. ### MooseFETGuest

That last bit is a little over simplified. A decaying squarewave has
the harmonics. There is a band around each that is the sidebands for
its decay. When you have a signal that you would describe as a
modulated version of some periodic function, the frequency content can
be described as having harmonics and side bands around them.

6. ### redbellyGuest

Well, yeah, but that's because it is a square wave. The harmonics
don't come about as a result of the decaying.

I interpreted the OP's question as to whether decaying of a wave will
generate harmonics. The answer is no.

Mark

7. ### MooseFETGuest

Yes, that is one way to take his question. Another would be to take
it as "do the other frequencies no longer land on multiples of the
fundamental". This is more along the line I took it.