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