Re: square wave harmonic theory (time domain)

Thomas Magma wrote:
Hello,
I'm trying to determine if the higher harmonics of a low frequency square wave are actually AM modulated. For instance, I can see the harmonics of a 1 KHz square wave all the way up at 100 MHz if I zoom into them on a spectrum analyzer. Are those harmonics really there when the 1 KHz square wave has finished it's transition and is in a steady state for half a millisecond? If I was to sample this steady state with a ultra fast ADC and FFT the samples, would I see the harmonics extending up through 100 MHz?

It's a bit of a mind bender when converting between the time and frequency domain in the case of a square wave.

Thanks,
Thomas Magma



As a general rule, if you modulate the fundamental, you modulate the harmonics.

Digitize it and run a Fourier Transform.

Otherwise, phase lock to a harmonic and see what demods out.

http://www.tinaja.com/glib/magsn01.asp


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Many thanks,

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Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
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