value of scale in CWT

I am working on the wavelet coefficients of Morlet wavelet. while using cwt(x,scales,'wname') command, how to determine the value of "scales".

Someone said the scales value is related to the center frequency of wavelet, then what is the relationship.

Thanks in advance.

Answer 1

[Wayne King]

The relationship is far from straightforward. You can use scal2frq in the Wavelet Toolbox to get an approximate scale to frequency conversion for a specified wavelet. To guide you in constructing a scale vector to input into cwt.m, you should think about what scales you wish to investigate and how fine the spacing between those scales should be.

[Dingguo Lu]

Wayne, please have a look at the following paper, if you have time:

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=1703938&tag=1

In this paper, page 4-6, the author mentioned 3 to7 correspond freq. from 700 to 1700 Hz at sampling freq. of 5000 Hz. He also mentioned 1 to 12 correspond freq. from 1.667 to 20 kHz at sampling freq. of 20kHz.

But when I use "scal2frq", it gives me different values. It is quite confusing. Would you please help to explain in detail?

[Dingguo Lu]

The wavelet I used is complex Morlet wavelet.