In the process, {HEAD ~ a series} of {TAIL ~ pulses} are produced, dependent upon the rotational speed of each drive 
of
In the process , { HEAD ~ a series } of { TAIL ~ pulses } are produced , dependent upon the rotational speed of each drive
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH