The squared signal is integrated over a period related to {HEAD ~ the frequency fm} to provide {TAIL ~ a dc signal} 
The squared signal is integrated over a period related to { HEAD ~ the frequency fm } to provide { TAIL ~ a dc signal }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL