%  Calculation of the rf-signal used for making the
%  spectrogram in pulsed wave ultrasound
%
%  Script using th automatic loadbalancing scheme. Performs
%  the simulation for 100 lines and then leaves Matlab to make
%  memory clean-up.
%
%  This script assumes that the field_init procedure has been called
%  Here the field simulation is performed and the data is stored
%  in rf-files; one for each rf-line done. The data must then
%  subsequently be processed to yield the image. The data for the
%  scatteres are read from the file sim_flow/scat_####.mat, so that the procedure
%  can be started again or run for a number of workstations.
%
%  Version 1.1 by Joergen Arendt Jensen, June 10, 1997.

%  Generate the transducer apertures for send and receive

f0=1e6;                  %  Transducer center frequency [Hz]
M=8;                     %  Number of cycles in emitted pulse
fs=100e6;                %  Sampling frequency [Hz]
c=1540;                  %  Speed of sound [m/s]
lambda=c/f0;             %  Wavelength [m]
width=lambda/2;          %  Width of element
element_height=5/1000;   %  Height of element [m]
kerf=0.05/1000;          %  Kerf [m]
focus=[0 0 60]/1000;     %  Fixed focal point [m]
N_elements=64;           %  Number of physical elements
Nshoots=5000;            %  Number of shots to be processed

% Do not use triangles

set_field('use_triangles',0);

%  Set the sampling frequency

set_sampling(fs);

%  Generate aperture for emission

emit_aperture = xdc_linear_array (N_elements, width, element_height, kerf, 1, 1,focus);

%  Set the impulse response and excitation of the emit aperture

impulse_response=sin(2*pi*f0*(0:1/fs:2/f0));
impulse_response=impulse_response.*hanning(max(size(impulse_response)))';
xdc_impulse (emit_aperture, impulse_response);

excitation=sin(2*pi*f0*(0:1/fs:M/f0));
xdc_excitation (emit_aperture, excitation);

%  Generate aperture for reception

receive_aperture = xdc_linear_array (N_elements, width, element_height, kerf, 1, 1,focus);

%  Set the impulse response for the receive aperture

xdc_impulse (receive_aperture, impulse_response);

%   Set a Hanning apodization on the apertures

apo=hanning(N_elements)';
xdc_apodization (emit_aperture, 0, apo);
xdc_apodization (receive_aperture, 0, apo);

%   Calculate scatter signal for all positions
i=1;
lines_done=0;
while (lines_done<200) & (i<=Nshoots)

  %  Check if the file already exits
  
  file_name = ['/data3/users_nbu/jaj/sim_flow_data/rf_data/rf_ln',num2str(i),'.mat'];
  cmd=['fid = fopen(file_name,''r'');'];
  eval(cmd);
  
  %  Do the processing if the file does not exits
   
  if (fid == -1)
    cmd=['save /data3/users_nbu/jaj/sim_flow_data/rf_data/rf_ln',num2str(i),'.mat i']
    eval(cmd);
     
    %   Load the data

    cmd = ['load /data3/users_nbu/jaj/sim_flow_data/scat_data/scat_',num2str(i),'.mat']
    eval(cmd)

    %   Calculate the received response

    [rf_data, tstart]=calc_scat(emit_aperture, receive_aperture, positions, amp);

    %  Store the result

    cmd=['save /data3/users_nbu/jaj/sim_flow_data/rf_data/rf_ln',num2str(i),'.mat rf_data tstart']
    eval(cmd)
    lines_done=lines_done+1;
  else
    fclose (fid);
    end
  i=i+1;
  end

%   Free space for apertures

xdc_free (emit_aperture)
xdc_free (receive_aperture)
field_end

%  Write the stop file if all simulations has been done

if (i>=Nshoots)
  save stop.mat i
  end