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