More precisely, the comparator 92 compares {HEAD ~ the density} represented by {TAIL ~ each dot signal}, with the reference density represented by the reference data 
represented by
More precisely , the comparator 92 compares { HEAD ~ the density } represented by { TAIL ~ each dot signal } , with the reference density represented by the reference data
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH