Dynamic Signal Acquisition

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shifting peak frequency

Many thanks, Doug,

 

I have shared the code and other information in a pdf file except for the data.

 

 

Kind regards

Jaefer

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If less than 10sec capture does not reproduce the issue, I would suspect it is your signal shifting. I am not familiar with your application to comment if it is expected for the signal to shift in frequency over time.

 

I guess you're trying to create a spectrogram (time vs frequency spectrum) and a real spectrogram/sonograph plot would make better sense than multiple plots for each segment of capture.

Santhosh
Soliton Technologies

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Message 12 of 13
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@Jaty22 wrote:

Thank you, Henrik,

 

I don't expect any frequency shift.

 

Happy weekend to you too.

 

Jaefer

 

 


Well, we don't know your setup, but if I think of a tank with a liquid (water) and a bubble source (air tube with nozzle), some influences come into my mind:

1. temperature change-> viscosity (or other properites of both media)  change -> rate change   and/or  the nozzle diameter will change with temperature

 

(whatever setup you (one) build, if you look close enough, you always build a thermometer :D)

 

2. turbulences/streams. your bubbles or other sources (temp 😉 , ...) create streams in the water, that also can have an influence of the physics on how the bubble comes off the nozzle

 

3. you need a stable air/gas pressure ... if you measure (coarsly) the frequency to pressure ratio you get an idea on how stable your pressure needs to be.

 

4. Any  vibration in the tank /nozzle will have an effect.  Your water tank has it's own resonances (more than one mode) .. your bubbles will exite these resonances .. maybe you see some beat frequencies 🙂

 

5. ??? 

time for my first coffee 😄

Greetings from Germany
Henrik

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