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RichP714

What is a Fourier Series?

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Wow!  I've subscribed to the Tinker Crate's, Eureka Crate's and Kiwi Crate's for my Son over the last 3 years.  He loves building them too.  He gets a new one every month in the mail and they are awesome.

 

Doctor Timothy used to geek out teaching me about Fast Fourier Transform's as applied to Spectral Analysis.  He was always riding me about whether I had completed my Fractal's, then he would chuckle.  He was a double E professor at the U and He was my boss for a number of years as well as an amazing mentor and I miss him very much since He passed.

 

Very interesting video.  I've never seen Fourier visualized in such an elegant manner.

Edited by Turbo
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a word of caution to the techs out here; If you have a digital oscilloscope that has an FFT function, you can't really rely on noise floor measurements (the low bitrate and IF section noisefloor will conspire to give erroneous readings.  FFT can give a good relative indication of power level  at various frequencies, but the noise floor is not accurate.  There was a guy a few years back that was trying to prove that cables made a difference (of course) by showing FFT plots on an o'scope; don't be that guy

 

https://www.edn.com/electronics-blogs/scope-insights/4413968/Know-the-Limitations-of-Your-Scope-s-FFT-Capabilities

Edited by RichP714
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30 minutes ago, RichP714 said:

a word of caution to the techs out here; If you have a digital oscilloscope that has an FFT function, you can't really rely on noise floor measurements (the low bitrate and IF section noisefloor will conspire to give erroneous readings.  FFT can give a good relative indication of power level  at various frequencies, but the noise floor is not accurate.  There was a guy a few years back that was trying to prove that cables made a difference (of course) by showing FFT plots on an o'scope; don't be that guy

 

https://www.edn.com/electronics-blogs/scope-insights/4413968/Know-the-Limitations-of-Your-Scope-s-FFT-Capabilities

Hahaha!  Too funny plotting it in the Time Domain.   I spend all of my time these days observing in the Frequency Domain and fretting over my G/T and C/Kt on my Ka and Q-Band birds and you would know exactly why.

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1 hour ago, Turbo said:

Hahaha!  Too funny plotting it in the Time Domain.   I spend all of my time these days observing in the Frequency Domain and fretting over my G/T and C/Kt on my Ka and Q-Band birds and you would know exactly why.

 

great example

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That is a really interesting way to visualize how these waveforms combine.  I’ve never seen anything like that before, thanks.

 

Another thing to be aware of in digital o’scope FFTs is the relationship between the sample rate and the frequency range.  I’ve seen people make that mistake a few times. 

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