Hi,
I just discover k-wave and I am very interested for an acoustic project.
But after crawling the documentation and the Internet and still wonder if there is a way to induce a doppler effect of the source by moving it ?
Thanks for your answer
Best regards
Hi Eric,
It may be possible to define a source.p_mask that traces the path you wish the source to travel, and then design your source.p such that the source 'moves' from one position to the next while (hopefully) maintaining the desired source shape and strength.
I will endeavour to create an example sometime in the next couple of weeks, and let you know of any difficulties I encounter.
Thanks,
Brad.
Thanks a lot.
I have to say that i am quite a begginer and your coming example will be helpful I believe
I have emailed you a simple example of using k-Wave to simulate the Doppler effect (to the email address you supplied on the forum). I hope it gets you started. I will also upload the example to the forum when I am back at my desk.
Brad.
You can find the Doppler example here.
EDIT: This example is now included within the B.0.3 release of the toolbox.
Hi Brad, I was wondering if I could also get an example of the moving source for doppler effect k-wave as well.
Thank you!
Mona
Hi Mona,
This example is now part of the toolbox. If you open the MATLAB documentation (by clicking on the blue question mark icon on the menu bar, then selecting "k-Wave Toolbox" from the contents list), you should see it under the heading "Time Varying Source Problems".
Brad.
Hi Brad!
Thanks for replying to my question and sorry for my late respond, I wasn't aware that you replied to me.
Yes, I did check the example, I think the part that I don't understand is how I define the source element, source.mask, to be active and deactive while the source is moving. For ex. if source is moving with the velocity of 1m/s in x direction and I have a grid of 100X100 (x,y) then I should somehow would be able to bring time to the position of the source. I don't know how. I tried so many ways of applying such as defining an array of the position for source, but it doesn't seem I did it right.
I understood about how to define a time varying signal, but I couldn't understand how to define a time varying position of a signal. As, we define the properties of source and sensor before, running the simulation that time appears.
I hope I explained well, I really appreciate if you could help me out in this case.
Mona
Hi Mona,
Unfortunately it's not completely straightforward, but it's certainly achievable. The basic idea is that the source mask is set to contain all the positions where the source will travel. For each grid point in the source mask, you can then define a time varying input signal assigned to source.p in the form:
source.p(1, :) = xxx; % signal at the first source point
source.p(2, :) = xxx; % signal at the second source point
...To make the source move, you can then "move" the driving signal between the grid points in the source mask. In the example in the toolbox, this is done using interpolation to make the transition smoother, but you could start just by jumping from one grid point to the next.
I hope that helps - if you deconstruct the toolbox example it should hopefully make more sense.
Brad.
Hi Brad!
Thank you very much! I actually found the example folder in the toolbox and I understood how you did that. My bad, I completely forgot that you have the m file for the examples:)
Thanks!
Mona
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