second differential amplifier means for generating an up down differential output signal which is {HEAD ~ a function} of {TAIL ~ the difference} in amplitude of said up and down output pulses; and 
of
second differential amplifier means for generating an up down differential output signal which is { HEAD ~ a function } of { TAIL ~ the difference } in amplitude of said up and down output pulses ; and
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH