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