I have two frequency spectrums as shown in the attached picture. The shape of the peaks are similar but they have only slightly shifted in frequency. I want to match the frequencies with similar peaks.
I tried the DP matching algorithm and backtrace the least cost path to find the frequencies that are most similar. I have attached that image too. I was intending to insert/delete/replace the amplitudes of these matching frequencies so that a score can be calculated between these two spectrums such that it is not influenced by these peaks. But seeing the least cost path output, there are some one-to-many mapping between the features (especially from reference to test pattern) which I am unable to understand how to interpret.
Is it possible to extract features that have similar peaks such as in the first picture ? If DP matching can do it, how do I apply the method ?
Thank you.
Call the frequencies f for the test pattern and g for the reference pattern.
You have a fundamental peak (absolute max) at f(0), resp. g(0). Then you have a second peak at f(1), g(1), a third at f(2), g(2), a fourth at f(3), g(3).
I would study the df(i) = f(i+1) -f(i) and dg(i) =g(i+1)-g(i).
It would also be interesting to see the energies under each peak. Define f'(i) the local minimum following f(i) and preceding f(i+1) and g'(i) similarly.
Then you define S(i) as the surface under the curve between f(i) (the max) and f'(i) (the min), and T(i) the surface below the curve between g(i) and g'(i).
Is there anything which one can say about S(i)/T(i), as i varies?
Is there anything interesting for the values of S(i+1)/S(i) and those of T(i+1)/T(i)?
More pragmatically, looking at the f(i), i=0,1, 2, 3, it looks like harmonic spectrum and the same for g(i).
Is it perfectly harmonic, or drifting away?oascillating around harmonic?
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