readLRI.m

function LRI1B = readLRI(file)
% Input: ascii file containing GRACE Follow-On LRI1B data 
% Output: matrix containing LRI1B data
% 
% cf. GRACE Follow-On Level 1B Data Product User Handbook
%
% Example: LRI1B = readLRI('LRI1B_2002-12-02_X_02.asc')

% Counts header lines and removes them.
header=0;
fid = fopen(file);
  while 1
      line = fgetl(fid);
      header = header+1;
      if (~isempty(strfind(line,'END OF HEADER')))
           break
      end
  end

% Reads the desired values from LRI1B data.
[gps_time, range, range_rate, range_acc, lighttime_corr, lighttime_rate, lighttime_accl, tma_corr, tma_rate, tma_accl, pitch_A, yaw_A, pitch_B, yaw_B] = textread(file,'%f %f %f %f %*f %f %f %f %f %f %f %f %f %f %f %*f %*f %*f %*f %*f','headerlines',header);

% Produces the matrix containing the desired values.
LRI1B = [gps_time, range, range_rate, range_acc, lighttime_corr, lighttime_rate, lighttime_accl, tma_corr, tma_rate, tma_accl, pitch_A, yaw_A, pitch_B, yaw_B];

end