Discover MakerZone

MATLAB and Simulink resources for Arduino, LEGO, and Raspberry Pi

Learn more

Discover what MATLAB® can do for your career.

Opportunities for recent engineering grads.

Apply Today

Thread Subject:
Wavelet Packets to Dominant Frequency

Subject: Wavelet Packets to Dominant Frequency

From: Jonathan

Date: 8 Jul, 2010 17:43:22

Message: 1 of 2

Greetings all,

I have been learning about wavelets for the past couple of weeks. I have the wavelet toolbox and have some trouble extracting certain information. Right now, my primary concern is how to extract a dominant frequency from a given transform. For example, if I have the coefficients of an N-level discrete wavelet transform (DWT), then I can easily see which level carries the most energy. I can even use the scal2freq function to get a pseudo-frequency that corresponds to that scale. However, if I want to think of a scale as a band of frequencies, how do I determine how far on each side of the pseudo-frequency to extend the bounds of this band?

This leads to thinking about the wavelet packet transform (WPT). I think this gives information about different scales at different times (just as the DWT) and gives this information for different frequency bands (determined by the position of a node in the packet tree). So, for this case, how can I find the dominant frequency of a given 1D signal at a certain time using the WPT coefficients? That is, given a particular node in the packet tree, what is the corresponding frequency band? I should note that I already understand the difference between the natural ordering of nodes and the frequency ordering of such.

Most of all, how can I do these calculations from the command line? Thank you for your help.

~Bubba

Subject: Wavelet Packets to Dominant Frequency

From: Wayne King

Date: 8 Jul, 2010 17:52:04

Message: 2 of 2

"Jonathan " <bubbathekid@gmail.com> wrote in message <i152nq$9sh$1@fred.mathworks.com>...
> Greetings all,
>
> I have been learning about wavelets for the past couple of weeks. I have the wavelet toolbox and have some trouble extracting certain information. Right now, my primary concern is how to extract a dominant frequency from a given transform. For example, if I have the coefficients of an N-level discrete wavelet transform (DWT), then I can easily see which level carries the most energy. I can even use the scal2freq function to get a pseudo-frequency that corresponds to that scale. However, if I want to think of a scale as a band of frequencies, how do I determine how far on each side of the pseudo-frequency to extend the bounds of this band?
>
> This leads to thinking about the wavelet packet transform (WPT). I think this gives information about different scales at different times (just as the DWT) and gives this information for different frequency bands (determined by the position of a node in the packet tree). So, for this case, how can I find the dominant frequency of a given 1D signal at a certain time using the WPT coefficients? That is, given a particular node in the packet tree, what is the corresponding frequency band? I should note that I already understand the difference between the natural ordering of nodes and the frequency ordering of such.
>
> Most of all, how can I do these calculations from the command line? Thank you for your help.
>
> ~Bubba

Hi, do you have the R2010b prerelease? If so, my answer is going to be a lot shorter :)

Wayne

Tags for this Thread

What are tags?

A tag is like a keyword or category label associated with each thread. Tags make it easier for you to find threads of interest.

Anyone can tag a thread. Tags are public and visible to everyone.

Contact us