When the signal k is increased in its amplitude to exceed {HEAD ~ these predetermined values}, {TAIL ~ the envelope detection circuit} 23 produces output signal of LO voltage 
When the signal k is increased in its amplitude to exceed { HEAD ~ these predetermined values } , { TAIL ~ the envelope detection circuit } 23 produces output signal of LO voltage
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH