http://www.k-wave.org/forum/topic/delay-between-symmetric-sensors-despite-symmetric-setup-in-k-wave Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 21:40:34 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/delay-between-symmetric-sensors-despite-symmetric-setup-in-k-wave#post-9226 Wed, 30 Jul 2025 07:40:21 +0000 ayitime 9226@http://www.k-wave.org/forum/ <p>This question has been resolved. </p> http://www.k-wave.org/forum/topic/delay-between-symmetric-sensors-despite-symmetric-setup-in-k-wave#post-9223 Wed, 16 Jul 2025 10:25:29 +0000 ayitime 9223@http://www.k-wave.org/forum/ <p>Hi,</p> <p>I'm running a 2D simulation in k-Wave using a line source placed symmetrically along the x-axis and a symmetrical arc-shaped sensor array (e.g., 6 elements). Both the source and sensor are symmetric in geometry.</p> <p>However, although symmetric sensor elements visibly receive the wavefront at the same time in the simulation movie, their recorded signals in combined_sensor_data show a delay of about 200 time steps (out of 1200), which is unexpected.</p> <p>I’m wondering:</p> <p>What might cause this delay between symmetric receivers?</p> <p>Could it be due to the use of kWaveArray, combineSensorData(), or the element size?</p> <p>Any ideas would be appreciated. Thanks!</p> <p>=================== code ==================<br /> clear;<br /> clc;</p> <p>Nx = 256;<br /> Ny = 256;<br /> dx = 0.5e-3;<br /> dy = dx;</p> <p>%% grid<br /> kgrid = kWaveGrid(Nx, dx, Ny, dy);</p> <p>%% medium<br /> medium.sound_speed = 1500;<br /> kgrid.makeTime(medium.sound_speed);</p> <p>%% source [array type]<br /> karrayy = kWaveArray;</p> <p>x_bias = -20e-3;<br /> y_width = 50e-3;<br /> start_pos = [x_bias, -y_width / 2];<br /> end_pos = [x_bias, +y_width / 2];<br /> karrayy.addLineElement(start_pos, end_pos);</p> <p>source.p_mask = karrayy.getArrayBinaryMask(kgrid);<br /> imagesc(kgrid.x_vec*1000, kgrid.y_vec*1000, source.p_mask);<br /> xlabel("y/mm"); ylabel("x/mm");<br /> axis equal; axis tight; colorbar;</p> <p>f1 = 100e3; % 0.1MHz<br /> sig1 = toneBurst(1/kgrid.dt, f1, 3);<br /> source.p = sig1;<br /> % plot(sig1);</p> <p>%% sensor [array type]<br /> karray = kWaveArray;<br /> radius = 50e-3;<br /> num_elements = 6;<br /> elem_pos = makeCartCircle(radius, num_elements, [0, 0]); </p> <p>radius_of_curv = 10e-3;<br /> diameter = 1e-3;<br /> focus_pos = [0, 0];</p> <p>for ind = 1:num_elements<br /> karray.addArcElement(elem_pos(:, ind), radius_of_curv, diameter, focus_pos);<br /> end</p> <p>sensor.mask = karray.getArrayBinaryMask(kgrid);<br /> imagesc(sensor.mask);<br /> xlabel("y/mm"); ylabel("x/mm");<br /> axis equal; axis tight; colorbar;</p> <p>input_args = {'DisplayMask',(source.p_mask | sensor.mask),...<br /> 'RecordMovie', true,...<br /> 'MovieName','video2',...<br /> 'DataCast', 'gpuArray-single',...<br /> 'PlotSim',true}; </p> <p>%% run<br /> sensor_data = kspaceFirstOrder2D(kgrid, medium, source, sensor, input_args{:});</p> <p>combined_sensor_data = karray.combineSensorData(kgrid, sensor_data);<br /> stackedPlot(combined_sensor_data); </p>