{TAIL ~ Spectrum analysis} can be used to create a profile of {HEAD ~ an active signal source} that can be analyzed to identify the type of source producing the signal 
{ TAIL ~ Spectrum analysis } can be used to create a profile of { HEAD ~ an active signal source } that can be analyzed to identify the type of source producing the signal
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH