My objective is to simulate echo from a phantom with two layers, for which I have set nonlinear parameters. However, when I reconstruct the B-mode image, I notice an unexpected line in the second layer, making the result look like it has three layers. I'm uncertain about what might be causing this issue in my code. Your assistance in resolving this matter would be greatly appreciated. Thank you.
The parameters that I use are as follows:
c0 = 1480; % [m/s]
alpha_coeff0 = 0.5; % [dB/(MHz^y cm)]
alpha_power0 = 1.9;
rho0 = 1000; % [kg/m^3]
BonA = 6;
% define properties
sound_speed_map = c0 * ones(Nx, Ny);%.* background_map;%;
density_map = rho0 * ones(Nx, Ny).* background_map;
alpha_coeff_map = alpha_coeff0 * ones(Nx, Ny);
% make circle inclusion SoS
sound_speed_map(cond1,:) = 1520;
% assign to the medium inputs
medium.sound_speed = sound_speed_map;
medium.density = density_map;
medium.BonA = 6*ones(Nx, Ny);