A tone detector for detecting a tone having {HEAD ~ a plurality} of {TAIL ~ targeted frequencies}, comprising: 
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A tone detector for detecting a tone having { HEAD ~ a plurality } of { TAIL ~ targeted frequencies } , comprising :
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH