The graphin Fig. 5 representssuchdistribution,wherecumu-
lativeamplitudesaredisplayedwithrespecttothedirection
(angle). Higherpeaksrefertothosedirectionsalongwhichthe
cumulativeamplitudeishigherandtherefore,probably,some
relevantinformationiscontained.Whentheobstaclerotates,
some peaksremain fixed,whileothersmove;attentionhastobe
put onthemovingpeaks,becausetheyconveytheinformationon
the angularposition θ; theyareindicatedin Fig. 5. Theangular
resolution oftheFFTalgorithmis Δθffi11.