% Message-ID: <3F68A9FF.78018661@udel.edu>
%Piotr,
%
%Here is a Matlab program to read loopstats files and construct Allan
%deviation plots. You can modify it for another language or file format.
%The key is in the first while loop.
%
%Dave
%
%
% This program computes graphical statistics from
% loopstat files produced by NTP.
%
clear all;
fid = fopen('loopstats', 'r');
[table, count] = fscanf(fid, '%f %f %f %f %f %f %f');
day = table(1:7:count);
sec = table(2:7:count) + (day - day(1)) * 86400;
offset = table(3:7:count);
freq = table(4:7:count);
jitter = table(5:7:count);
wander = table(6:7:count);
poll = table(7:7:count);

y1 = offset; i = 1; d = 16;
while length(y1) >= 10 
	u = diff(y1) / d;
	v = diff(u);
	z1(i) = sqrt(mean(v .* v) / 2);
	m1(i) = d;
	y1 = y1(1:2:length(y1));
	i = i + 1; d = d * 2;
end

loglog(m1, z1 * 1e6, '-k')
axis([1 1e5 1e-4 100]);
xlabel('Time Interval (s)');
ylabel('Allan Deviation (PPM)');

pause