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- Sorting target lists on the basis of RTT to bring those landmarks at the top (of the Target files) which have lowest RTT values. This technique fails since in some cases the top three landmarks in the Target files are located thousands of kilometers apart. I don't know how these landmarks managed to have such low RTT values from the target. CBG with tri-lateration failed on such a sorting technique .. because landmarks were way off!
Results, some discrepancies and explanation
In the spreadsheet we have made various calculations in order to understand the results.
1. Amount of NaNs in error for multi-lateration and tri-lateration
67/171 for multi-lateration and 6/171 for tri-lateration.
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NaN (Not a Number) is a value of numeric data-type representing an undefined or unrepresentable value, especially in floating point calculations. \[Reference and more here\|[http://en.wikipedia.org/wiki/NaN|http://en.wikipedia.org/wiki/NaN]\]. |
According to the CBG code NaNs represent "bad pairs that lead to no region". This means that landmarks that fail to produce intersection regions, consequently also fail to produce an estimate for the location of the target and instead giving out an erroneous value. Author has handled such values with NaN (code snippet below).
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if constraintType
warning('Trying speed of light')
constraintType = 0;
% switch the constraint type and try again
\[locest,actual,error,regarea,distNearestLandmark,target_id,constraintType,inRegion\] = geolocate(file,extension,hullbool, constraintType, bestlineTable);
return;
else
% find the badPairs that lead to no region, write them to stdout
badPairs = analyzeNoRegion( measurements )
%error(\['No SOL intersection region for ', char(file)\])
region = \[NaN NaN\];
locest = \[NaN NaN\];
error = NaN;
regarea = NaN;
results = \[target_id error; distNearestLandmark regarea; locest; actual; region\];
dlmwrite(\[char(file),char(extension)\],results,' ');
return;
end;
if constraintType
warning('Trying speed of light')
constraintType = 0;
% switch the constraint type and try again
\[locest,actual,error,regarea,distNearestLandmark,target_id,constraintType,inRegion\] = geolocate(file,extension,hullbool, constraintType, bestlineTable);
return;
else
% find the badPairs that lead to no region, write them to stdout
badPairs = analyzeNoRegion( measurements )
%error(\['No SOL intersection region for ', char(file)\])
region = \[NaN NaN\];
locest = \[NaN NaN\];
error = NaN;
regarea = NaN;
results = \[target_id error; distNearestLandmark regarea; locest; actual; region\];
dlmwrite(\[char(file),char(extension)\],results,' ');
return;
end;
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