HIGH QUALITY TPU DVD Video Released from Jack Durban

[Feynman]

@aleks
Can you explain how you are differentiating between square, saw, and sine on the Fourier Transforms?

@marco
Thanks for the info   

@FT'ers
this was a great idea, really damn clever

@all
Anyone got a good copy of the raw video from which these FTs were determined? 

[EMdevices]

Feynmen,  did you not download the DVD that Jack provided?   In that previous post I included the frame that shows where the sounds get produced (right as he activates the tpu by inserting a magnet inside of it)  You can also hear the same sound in the low resolution videos available online at google, youtube, etc.. 

I don't have any "raw data" as in exported numbers,  I just exported the audio clip to a wave file (using Ulead), and played it with the spectrum program.   Do you want the short wave file?  I can posted when I get home if you're interested. 

EM

P.S.  @Marco,   I not sure what you're looking at there, but there is no frequency content in the buzzing above 5 kHz,  there is however a continuous 12 kHz and 17 kHz  (approx)   frequency that I see, which is not part of the buzzing sound, so I condensed the chart to the frequencies you see.   I'll have to analyze the old video sounds, maybe they're different, which would mean distortion  introduced due to resampling to a lower bit rate perhaps.

[Feynman]

Didn't realize this was in Jacks' video.  I'll check when I get home tonite to see if I can also do FT.  Thanks 

[aleks]

Can you explain how you are differentiating between square, saw, and sine on the Fourier Transforms?

Sine wave is a single spectral component, without obvious connection to other frequencies. Obvious connections are: equally-spaced side bands and harmonic multiplies.
Square wave consists of odd (1,3,5,7,etc) harmonics.
Saw-tooth waves consists of all (1,2,3,4,5,6) harmonics.

Of course, knowing phase of harmonics is also important to make any final judgement. Unfortunately, spectral power plots do not give any information about harmonics phase.

By the way, the image EMdevices posted is actually looking like 100Hz square wave oscillator with 3.2kHz square wave oscillator running together, because I can see 200 Hz spaced traces throughout the spectrum. Another possibility is that 3.2kHz (or 3.5kHz) is not a square wave signal, but some kind of resonant frequency of the system. If this is really a 3.5kHz square wave frequency, I do not see its higher components. On the other hand, it may be a 1.1kHz saw-tooth (or 550 Hz square) wave: you can can clearly see 2.2, 3.3 and 4.4kHz traces (around these), with a pretty expected intensity progression.

Well, without knowing fundamental frequency it's easy to mix square wave and saw-tooth wave. Common "power line" buzz can be modeled both with high-passed square wave and saw-tooth wave.

[aleks]

octave harmonic at 3.9936 kHz.

It's won't be an 'octave harmonic', it will be a 500th overtone. 500*7.8...