%seakeeping.m 
%Program to produce calibrated data for seakeeping lab
%author - Stephen Licht 
%MIT Towing Tank 
%April 2003

hold off; zoom off; clear all; close all; 

%This will prompt you to select a .i32 file to read data from, and will ask you to
%select start and end points for the data. It will then will spit out four
%vectors of data, which are:

%  'heave_position'
%  'pitch_angle'
%  'surface_height'
%  'time'

%These variables will also be saved in a .mat file with the same
%name as the .i32 file that you selected (with the extension .mat so
%as to avoid writing over the raw data file.

%Enter the calibration coefficients supplied by you friendly TA for the
%heave and pitch sensors, as well as the wave probe calibration that you
%obtained, in the appropriate place below:

%----------------------------------------------------------------------
%----------------------------------------------------------------------
%Enter calibration data here

heave_coefficient = 1    %cm/volt
pitch_coefficient =  1   %rad/volt
pitch_offset =       1   %volt
wave_probe_coefficient = 1     %cm/volt
wave_probe_offset =  1    %volt

%----------------------------------------------------------------------
%----------------------------------------------------------------------

%You must have the file 'parsedl2.m' in your matlab path or in the
%directory from which you run this code!  Ignore the warning that some
%later versions of Matlab generate when you run parsedl2.

%open window to get  data file: 
[filen, pathn] = uigetfile('*.i32','OPEN Lab Data File'); 
filestub = [pathn '' filen]; 
    
[pathstr,filename,ext,versn] = fileparts(filestub)

%Load i32 format data and create array with channel 1,2,3,4 in columns: 
[data_raw]= parsedl2(filestub,4)'; 
    
%Apply calibration coefficient and offset for all sensors (except for drag sesnsor):
heave_position = data_raw(:,2)*heave_coefficient; 
pitch_angle = (data_raw(:,3) + pitch_offset)*pitch_coefficient;
surface_height = (data_raw(:,4)+wave_probe_offset)*wave_probe_coefficient;

%Create time scale vector:
dt=.005; %Sampling at 200Hz 
time=0:dt:(length(data_raw)-1)*dt; 
    
%Get region of interest by displaying data and having user pick
%desired data start and end times:
figure
plot(time,heave_position); 
ylabel('Heave Position (cm)')
xlabel('Time (s)');
title('Pick Start Point and End Point');
[a,b]=ginput(2); 
[a]=round(a)/dt; 

%Shorten all data vectors they only include the desired range:
heave_position=heave_position(a(1):a(2),:); 
pitch_angle=pitch_angle(a(1):a(2),:); 
surface_height=surface_height(a(1):a(2),:); 
time=time(a(1):a(2));

save(filename,'heave_position','pitch_angle','surface_height','time');