If the IBS modem 28 is external to the receiving circuitry 91, then a A/D converter 96 converts {HEAD ~ the analog signals} back into {TAIL ~ digital signals} 
back into
If the IBS modem 28 is external to the receiving circuitry 91 , then a A / D converter 96 converts { HEAD ~ the analog signals } back into { TAIL ~ digital signals }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL