# Waveforms

Discussion in 'Homework Help' started by thebiglad, Apr 6, 2005.

Apr 6, 2005
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[attachmentid=540]Hi guys can somebody help me with this i must have been absent from tech the day we covered complex waveforms.
Can anybody tell me what features of a waveform indicate that it con tains no even harmonics.(waveform included)
Thanks for any help or even pointed in the right direction

2. ### Brandon Senior Member

Dec 14, 2004
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Rather than just tell you, this is a simple thing you can do with a graphing calculator or matlab and just see what happens.

Just make a function like

y=cos(x)+cos(3x)+cos(5x)+cos(7x) should be enough and see how it plots.

Do the same thing and add the even hamonics to it.

The waveform you showed had no harmonics, only the fundamental, ie. the cos(x).

WHen you start adding a harmonic is just the addition of a higher frequency signal to the fundamental signal which will begin to add more peaks and valleys as you add more and more harmonics.

3. ### psandip612 New Member

Mar 23, 2005
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well you can go for fourior analusis which helps in even and odd waveforms analusis

4. ### David Bridgen Senior Member

Feb 10, 2005
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You could "go for" Fourier analysis too.

5. ### Tekker Active Member

Apr 22, 2005
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If it doesn't contain any even harmonics and it only contains odd harmonics, then wouldn't that be a square wave?

-tkr

6. ### David Bridgen Senior Member

Feb 10, 2005
278
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A square wave does indeed consist of the fundamental plus only odd harmonics, but their amplitudes are in the same proportion to that of the fundamental as their order.
In other words, the third harmonic has a magnitude of one 3rd the fundamental's, the fifth harmonic one 5th of the fundamental's, the seventh one 7th etc.

A different recipe results in something other than a true square wave.

7. ### Tekker Active Member

Apr 22, 2005
33
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Ahhh yes, that's right.... Thanks for the correction David!

-tkr