% Simple MABEL data reader; reads in MABEL time and elevation data and plots

% this information in two figures: (1) time of flight vs. vertical elevation;

% and (2) ground distance covered during flight vs. vertical elevation.

% The plots will show the entire returned photon set, so zoom in accordingly 

% to see the apparent ground returns (they should be fairly obvious, even in

% noisy figures, with some minor searching).



clear all; close all;



% for instance, h5filename = 'mabel_l2_20120402t092900_008_1.h5';

h5filename = 'insert MABEL filename here'; 



% generates a single-column array of all returned-photon elevations

elev_initial = hdf5read(h5filename,'/channel003/photon/ph_h'); 



% generates a single-column array of all corresponding returned-photon times

time_initial = hdf5read(h5filename,'/channel003/photon/delta_time'); 



% plot up returned photon data with respect to time



figure(1)

plot(time_initial,elev_initial,'b.','MarkerSize',0.10)

title(h5filename)

xlabel('time (sec')

ylabel('elevation (meters)')







% use GPS-derived velocity and time to calculate approximate distance covered on the ground



time_novatel = hdf5read(h5filename,'/novatel_ins/delta_time');

velocity_east = hdf5read(h5filename,'/novatel_ins/velocity/ins_v_east');

velocity_north = hdf5read(h5filename,'/novatel_ins/velocity/ins_v_north');



velocity_total = sqrt((velocity_east).^2.+(velocity_north).^2);



% convert from m/s to km/hr



velocity_kmhr = (velocity_total.*3600)./1000;



% calculate maximum and minimum aircraft velocities from the 30-second data

% segment



min_vel = min(velocity_total);

max_vel = max(velocity_total);



% set threshold for continuing to determine distance -- if velocity in the

% data segment varies by or less than 10 km/hr (2.8 m/s), calculate the average

% velocity and move forward to calculate the distance covered in the data

% segment



if max_vel-min_vel > 20;

break

else

    avg_vel = mean(velocity_total);

end



% determine distance covered in 30-second data segment



distance = avg_vel*max(time_initial);



% determine distance covered in each consecutive time step (necessary for

% plotting against elevation data)



distance_initial = time_initial*(distance/max(time_novatel));



% plot returned photon data with respect to distance



figure(2)

plot(distance_initial,elev_initial,'r.','MarkerSize',0.10)

title(h5filename)

xlabel('distance (km)')

ylabel('elevation (meters)')