Code covered by the BSD License  

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Bit Packet Analyzer

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Bit Packet Analyzer

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The Bit Packet Analyzer can be used to analyze bit streams for repeating patterns (e.g. preamble)

BitPacketAnalyzer (inVector, lenPack)
%% BitPacketAnalyzer by Igal Yaroslavski
%
%  Display bit packets side by side, with variable packet length and variable
%  number of packets to display. The reason being an easy way to analyze packet
%  patterns e.g. preambles and etc

function BitPacketAnalyzer (inVector, lenPack)
% InVector: vector of bits to analyze
% lenPack: Length of the packet, at @ lenth bit graphics switch to new line
% if inVector contatins more than N*lenPack elements the vector is zero
% padded to the next pack.
% maxNpacks: max packets to display, if there's more - show only first packets.

maxNpacks = 100;

%% Shape data
nElements = numel(inVector);

if (size(inVector,2) > 1) % if
    inVector = reshape(inVector,nElements,1);
end

numPackets = nElements/lenPack;
intNumPackets = ceil(numPackets);

if(numPackets > maxNpacks) % if there's more packets then nMax, truncate the input
    intNumPackets = maxNpacks;
    outVector = inVector(1:intNumPackets*lenPack);
elseif(numPackets ~= intNumPackets) %zero padding is needed
    nZeros = lenPack*intNumPackets - lenPack*numPackets;
    outVector = [inVector; zeros(nZeros,1)];
else
    outVector = inVector;
end

clear inVector numPackets;

% shape the data to show packets in lines
outVector = (reshape(outVector, lenPack, intNumPackets))';

%% Find vertices for patches
outVector = flipud(outVector);
[y,x]=find(outVector == 1);
x = x'; y = y';
xpatch = [x-1; x ; x; x-1];
ypatch = [y-1; y-1; y; y];

%% Plot patches
f = figure('visible','off');
ha = axes('visible','off','XTickMode','manual');
h = patch(xpatch,ypatch,'k');

set(h,'Parent', ha);
set(ha,'XTick', []);
set(ha,'YTick', []);
axis(ha, 'tight');
set(ha,'visible','on');
set(f,'visible','on');

title(['Bit Packet Analysis, Packet Length = ', ...
    num2str(lenPack), '# of Packets = ', num2str(intNumPackets)]);
end

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