In {TAIL ~ operation}, the variable delay element 30 provides a variable delay whose magnitude is directly related to the composite of the degrees of {HEAD ~ operation} of the differential sections D1 and D2 
In { TAIL ~ operation } , the variable delay element 30 provides a variable delay whose magnitude is directly related to the composite of the degrees of { HEAD ~ operation } of the differential sections D1 and D2
OTH TAIL TAIL TAIL TAIL TAIL 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 OTH OTH OTH OTH OTH OTH OTH