When the aperture size defined by the sectors 12a and 12b reaches the aperture value A, i.e., when N=A, then {HEAD ~ that terminal} of AND gate 45 associated with {TAIL ~ comparator} 43 receives low level signal  
associated with
When the aperture size defined by the sectors 12a and 12b reaches the aperture value A , i.e. , when N = A , then { HEAD ~ that terminal } of AND gate 45 associated with { TAIL ~ comparator } 43 receives low level signal
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH