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