k-Wave User Forum » Topic: Not seeing returning ultrasound echoes in ring array ultrasound simulation

k-Wave User Forum » Topic: Not seeing returning ultrasound echoes in ring array ultrasound simulation http://www.k-wave.org/forum/topic/not-seeing-returning-ultrasound-echoes-in-ring-array-ultrasound-simulation Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 05:21:18 +0000 http://bbpress.org/?v=1.0.2 <![CDATA[Search]]> q http://www.k-wave.org/forum/search.php Bradley Treeby on "Not seeing returning ultrasound echoes in ring array ultrasound simulation" http://www.k-wave.org/forum/topic/not-seeing-returning-ultrasound-echoes-in-ring-array-ultrasound-simulation#post-7897 Sun, 01 Nov 2020 20:40:51 +0000 Bradley Treeby 7897@http://www.k-wave.org/forum/ I can't run your code (there are custom functions and datasets). Have you tried increasing the simulation time? You could also try increasing the sound speed / density contrast while you're debugging to make it easier to see the reflected signals (the current impedance contrast is very small). Brad. fg9716 on "Not seeing returning ultrasound echoes in ring array ultrasound simulation" http://www.k-wave.org/forum/topic/not-seeing-returning-ultrasound-echoes-in-ring-array-ultrasound-simulation#post-7872 Tue, 06 Oct 2020 14:40:35 +0000 fg9716 7872@http://www.k-wave.org/forum/ Hello. I am trying to run an ultrasound ring array simulation with a heterogeneous speed of sound medium and a time-varying pressure source. I can see the original transmitted signal in all sensor channels, but I am not seeing the reflection signals off of the object I have embedded in my medium. I cannot see where the mistake is. Any help would be greatly appreciated. ___________________________________________________________ load TransducerPositions_1024.txt TransPos=TransducerPositions_1024(1:4:end,:); %Convert 1024 element array to 256 %=================================================== % User Input %=================================================== % Select the simulation type % % 1. C++ Simulation from Matlab % 2. CUDA Simulation from Matlab % 3. MATLAB simulation % SIMULATION_TYPE = 1; SIGNAL_AMPLITUDE = 40; % [Pa] SIGNAL_BANDWIDTH = 0.80; % [ratio], e.g. 50% --> 0.50 SIGNAL_CENTER_FREQUENCY = 1.5; % [MHz] SIGNAL_SAMPLING_FREQUENCY = 12; % [MHz] %================================= % Computational Grid %================================= Nx = 256; % Number of grid points in the x direction Ny = 256; % Number of grid points in the y direction Nz = 30; % Number of grid points in the z direction dx = 1e-3; % Grid point spacing in the x direction [m] dy = 1e-3; % Grid point spacing in the y direction [m] dz = 1e-3; % Grid point spacing in the z direction [m] kgrid = kWaveGrid(Nx, dx, Ny, dy, Nz, dz); %================================= % Medium %================================= %create cylinder embedded in medium cx=128; cy=128; cz=3; radius=50; height=25; medium.sound_speed=makeCylinder(Nx, Ny, Nz, cx, cy, cz, radius, height); %create sphere inside cylinder inside medium cx=128; cy=128; cz=15; radius=5; medium.sound_speed=medium.sound_speed+makeSphere(Nx, Ny, Nz, cx, cy, cz, radius); medium.sound_speed(medium.sound_speed==0)=1500; %water bath sound speed medium.sound_speed(medium.sound_speed==1)=1450; %cylinder object sound speed medium.sound_speed(medium.sound_speed==2)=1600; %sphere object sound speed medium.density=1000*ones(Nx,Ny,Nz); %% % Init time array dt = 1/(SIGNAL_SAMPLING_FREQUENCY*10^6); c0_peak = max(max(max(medium.sound_speed))); CFL = (dt/dx)*c0_peak; if CFL>0.3 disp("WARNING: CLF number is larger than 0.3, which could result in numerical errors!"); end kgrid.makeTime(medium.sound_speed, CFL); %================================= % Source %================================= tc = gauspuls('cutoff',SIGNAL_CENTER_FREQUENCY*10^6 ... ,SIGNAL_BANDWIDTH,[],-40); t = -tc : dt : tc; signal = SIGNAL_AMPLITUDE*gauspuls(t,SIGNAL_CENTER_FREQUENCY*10^6,SIGNAL_BANDWIDTH); p0 = zeros(size(kgrid.t_array)); p0(1:length(signal)) = signal; source.p = p0; %================================= % Sensors %================================= ring.position = ceil((TransPos*1e-3./dx - 0.5)); ring.position(:,1) = ring.position(:,1) + Nx/2; ring.position(:,2) = ring.position(:,2) + Ny/2; % define a sensor mask through the central z-plane sensor.mask = zeros(Nx, Ny, Nz); for idx = 1:length(ring.position) sensor.mask(ring.position(idx,1),ring.position(idx,2), ceil(Nz/2)) = 1; end %=================================================== % Run Simulation %=================================================== input_args = {}; source.p_mask = zeros(Nx, Ny, Nz); source.p_mask(ring.position(eleNum,1),ring.position(eleNum,2),Nz/2) = 1; switch SIMULATION_TYPE case 1 % Run the C++ simulation sensor_data = kspaceFirstOrder3DC(kgrid, medium, source, sensor, input_args{:}); case 2 % Run the CUDA simulation sensor_data = kspaceFirstOrder3DG(kgrid, medium, source, sensor, input_args{:}); case 3 % Run the MATLAB simulation sensor_data = kspaceFirstOrder3D(kgrid, medium, source, sensor, input_args{:}); end