{TAIL ~ A resulting pressure signal} and density signal are analyzed to extract at least a first and second pressure value and at least a first and second density value, where the first pressure and density values occur at {HEAD ~ a first time}, and the second pressure and density values occur at a second time 
{ TAIL ~ A resulting pressure signal } and density signal are analyzed to extract at least a first and second pressure value and at least a first and second density value , where the first pressure and density values occur at { HEAD ~ a first time } , and the second pressure and density values occur at a second time
TAIL TAIL TAIL 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH