http://www.k-wave.org/forum/topic/steering-angle-plane-wave Support for the k-Wave MATLAB toolbox en-US Tue, 12 May 2026 23:42:01 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/steering-angle-plane-wave#post-7044 Thu, 12 Sep 2019 10:04:42 +0000 Bradley Treeby 7044@http://www.k-wave.org/forum/ <p>Hi Farnaz,</p> <p>I'm not familiar with the ricker function, but essentially, you need to add the appropriate time offset to the signal for each element (group of four grid points).</p> <p>One simple way would be to create the time signal with a lot of trailing zeros, then replicate this to match the total number of grid points in your source with <code>repmat</code>. Finally, for each time signal, use <code>circshift</code> to add the appropriate amount of zeros to the beginning to give the desired time offset (in discrete steps of <code>kgrid.dt</code>).</p> <p>If using discrete time delays is a problem, you could also use the equation of the ricker wavelet and sample it with the appropriate offsets.</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/steering-angle-plane-wave#post-7023 Tue, 27 Aug 2019 08:58:21 +0000 Farnaz 7023@http://www.k-wave.org/forum/ <p>Hi, </p> <p>In the Steering linear angle example the delay is applied through the toneBurst function as offset but my problem is slightly different and I am wondering whether there are other functions to apply delays. (I have 2D simulation so I can't use transducer class)<br /> I am using source.u with a ricker wavelet. I have a 2D linear transducer with 4 grid points for each element and 4 grid point for kerf. How do I apply delays for different angles in this scenario? </p> <p>% =========================================================================<br /> % Define Source<br /> % =========================================================================<br /> kerf = 4;<br /> groupspacing = 4;<br /> element_num = 128;<br /> source_shape = reshape((1:kerf)' + (0:element_num-1)*(kerf+groupspacing), 1, []);</p> <p>% % define source mask for a linear transducer with an odd number of elements<br /> num_elements = element_num*groupspacing ;<br /> x_offset = 1; % [grid points]<br /> source.u_mask = zeros(Nx, Ny);<br /> source.u_mask(x_offset , source_shape ) = 1 ; </p> <p>%activate middle elements<br /> active_elements = element_num/2 ;<br /> sensor_offset_mask = groupspacing*element_num/4+kerf*(element_num/4)-1 ;<br /> source.u_mask(x_offset , 1:sensor_offset_mask) = 0 ;<br /> source.u_mask(x_offset , Ny-sensor_offset_mask:Ny)=0 ; </p> <p>% define the properties of the tone burst used to drive the transducer<br /> sampling_freq = 1/kgrid.dt; % [Hz]<br /> steering_angle = 0; % [deg]<br /> element_spacing = dx; % [m]<br /> tone_burst_freq = 5e6; % [Hz]</p> <p>source.ux = ricker(tone_burst_freq,120, kgrid.dt) ; </p> <p>Thanks in advance, </p>