k-Wave

1. yinhaoscu
   

   Member
   Joined: Jun '12
   Posts: 11

   I modified the example_us_bmode_linear_transducer.m matlab code to do simulation, and set sampling frequency to fixed 40MHz instead of CFL related one.

   x = 50e-3;
   dx = 0.15e-3; % [m]
   Nx = ceil(x/dx);

   medium.alpha_coeff = 0.5;
   % [dB/(MHz^y cm)]
   medium.alpha_power = 1.0; % linear relationship between attenuation and frequency
   medium.alpha_mode = 'no_dispersion';
   % medium.BonA = 6; comment this line to ignore the nonlinear effect

   tone_burst_freq = 3e6; % [Hz]
   tone_burst_cycles = 5;

   if central frequency was set to 3MHz, the simulation results are very good. However when 5MHz was used, the results was bad. Any one could give me some suggestion.

   Posted 12 years ago #

2. Julian
   

   Member
   Joined: Apr '13
   Posts: 1

   Hi yinhaoscu,

   I think the grid doesn't support frequencies higher than 3.42 Mhz. You can calculate the maximum frequency by f_max = c_min/(2*dx). c_min denotes the minimal velocity of sound and dx the spacing between the grid points.

   If you want to know more, just look around in the forum.

   Hoping to help,

   Julian

   Posted 12 years ago #

3. yinhaoscu
   

   Member
   Joined: Jun '12
   Posts: 11

   Julian, thanks a lot for your reply. If convenient, would you please give me a link on the related topic in this forum about the calculaton of maximum supported frequency.

   Posted 12 years ago #

4. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,643

   There is some information in Sections 2.7, 3.2, and 3.4 in the k-Wave Manual that you might find helpful in regards to the grid spacing and maximum supported frequency.

   Posted 12 years ago #

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