When {HEAD ~ the counted number} reaches {TAIL ~ the predetermined maximum value}, the squelch alarm signal is produced and maintained thereafter until a low level or a negative signal is applied from the comparator 21 to the AND gate 33 and the reset terminal R 
When { HEAD ~ the counted number } reaches { TAIL ~ the predetermined maximum value } , the squelch alarm signal is produced and maintained thereafter until a low level or a negative signal is applied from the comparator 21 to the AND gate 33 and the reset terminal R
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH