phyphox Forums
High resolution frequency detektor - Printable Version

+- phyphox Forums (https://phyphox.org/forums)
+-- Forum: App-Feedback (https://phyphox.org/forums/forumdisplay.php?fid=6)
+--- Forum: Feature requests (https://phyphox.org/forums/forumdisplay.php?fid=8)
+--- Thread: High resolution frequency detektor (/showthread.php?tid=656)



High resolution frequency detektor - Henrik_V - 02-17-2020

Hi,
great tool ..  
I was trying to detect small frequency variations with my android and here is my feature request:
A high resolution frequency detector
Autocorrelation and FFT based solutions are limited by the samplerate and sample size, one would be the reciproque counting method.

But there are even better methods: sine fitting
EVALUATION OF A STANDARDIZED SINE WAVE FIT ALGORITHM
Peter Händel
Abstract:
The IEEE Standard 1057 provides algorithms for fitting the parameters of a sine wave to noisy discrete time observations....



Or doing some more math on a FFT like:
https://forums.ni.com/ni/attachments/ni/170/83640/1/tm3bb.ppt
found in
https://forums.ni.com/t5/LabVIEW/Extract-Single-Tone-Information-from-Hann-Spectrum/m-p/139348#M83640

works great in LabVIEW, but I don't know what is protected in that part....

Both method prefer sine like signals but also work on everything that is periodic Smile
(one could apply a bandpass before)  

My experiments are measure small frequency changes in a LC oscillator .. and detect small changes in µ_r or C ... 
(and try to power the circuit from the mic bias .. ;Wink )  

Regards
Henrik


RE: High resolution frequency detektor - Sebastian Staacks - 02-20-2020

Thanks for the suggestion. I intended to implement some other methods for a while now, but never got around to it. I will bump it up a little bit on my todo list, but not yet sure when I will get to it. (This is something that could easily be contributed to our open source project as a new analysis module by someone who can write Java and/or Swift, just saying Wink )