In the absence of using {TAIL ~ the present invention} {HEAD ~ amplitude degradation} can create unacceptable DF errors 
In the absence of using { TAIL ~ the present invention } { HEAD ~ amplitude degradation } can create unacceptable DF errors
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH