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