scanning a next frequency channel in a synchronous scan mode in response to the failure, wherein the implantable device scans {HEAD ~ a frequency channel} for {TAIL ~ a same time interval} as the external device when in the synchronous scan mode 
for
scanning a next frequency channel in a synchronous scan mode in response to the failure , wherein the implantable device scans { HEAD ~ a frequency channel } for { TAIL ~ a same time interval } as the external device when in the synchronous scan mode
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 TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH