executing, by the processor, an executable comprising a relative positioning system calculating substantially continuously during {HEAD ~ the moving a current position} of the user relative to {TAIL ~ the fixed staring point} based exclusively on the signal; and 
executing , by the processor , an executable comprising a relative positioning system calculating substantially continuously during { HEAD ~ the moving a current position } of the user relative to { TAIL ~ the fixed staring point } based exclusively on the signal ; and
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH