%Shane Crockett - 11 JUN 98
%Plot of instantaneous power vs. time

% Power was determined by summing the columns of the spectrogram, and dividing by the number of elements in that column (numerical mean).
%This was then plotted vs. time.  The secondary peak is probably larger than expected because less energy was removed during the prewhitening.

freqstep = 25/65;
%newsig = (DChirp).*freqstep; 

ipwrtt = sum(DChirp).*(freqstep);
pt = ((.32*10^-6)./2).*[1:length(ipwrtt)].*1000;													%converts x scale to msec
%plot(pt,ipwrtt)
%xlabel('time(msec)')
%ylabel('Power')
%axis([0 max(pt) 0 max(ipwrtt)])
%title(filename)
%set(gcf, 'Position', [50 25 400 350])

% Autocorrelates the power using circular autcorrelation

acorr																								%acorr is an m.file
G = ceil(length(auto)/4);
auto = auto(G:G + ceil(G/2));																				%creates vector of relevant data points
auto = auto./max(auto);																				%scales the data between one and zero
at = ((.32*10^-6)/2).*[1:length(auto)]*1000;														%converts x scale to msec				
plot(at,auto)
axis([0 max(at) min(auto) 1])

titl = ['Power-autocorrelation of ' filename];
title(titl)

xlabel('Time (msec)')
ylabel('Lagged Autocorrelation')


% Determining background level
% This is accomplished by sampling the last 10% of data points (assuming that no phenomena occur during this time) and taking the mean of this data.

background = auto(length(auto) - round(.1*length(auto)):length(auto));
backbar = mean(background);

% Statistical data.

% Creates an output file to record the following statistics
% Output file is named filename.txt where the filename is the name of the raw signal file

name = [filename '.txt'];
diary(name);

fprintf(filename); fprintf(':\n');

%Optimally dechirped instantaneous power and Total Electron Content
var = find(FOM == max(FOM));
fprintf('\nThe TEC is %g. \n',TEC(var))
fprintf('\nThe optimally dechirped average power is %g. \n',mean(ipwrtt))

% Determining the 1/e value.
r = find(auto <= (1)/exp(1));
check = isempty(r);
if check == 0
   text(at(r(1)- 1), auto(r(1)-1), ' -1/e')
   fprintf('\nThe power-autocorrelation 1/e width is %g msec. \n', at(r(1) - 1))

% Calculating the Signal-to-Noise Ratio
% Determining the amount of lag to the second peak and the value at that time.
echo off
findmax																						%executes an m.file named findmax
SNR = 10*log(lagmax/backbar);
if at(r(1)) <= .01
   if SNR >= 5
      fprintf('\nThe SNR is %g dB. \n',SNR)
   text(at(lag), lagmax, '  <--- local max - possible secondary')
   fprintf('\nThe lag is %g sec. \n',lag*(.32*10^-6)*.5)
else
end
else
end
else
end

%Determining the Peak Power
fprintf('\nThe peak power is %g. \n',max(ipwrtt))

% Determining Contrast (Peak-to-Median Power)
fprintf('\nThe Contrast of the signature is %g. \n',max(ipwrtt)/median(ipwrtt))

fprintf('\n _____________________________________ \n\n');
diary off

% Administrative to free space
clear freqstep newsig pt auto at background backbar lagmax lag r ip pad u x