Since {HEAD ~ SATPS data} gives good results at {TAIL ~ longer distances}, SATPS data is used when the distance is greater than or equal to the optical threshold 
Since { HEAD ~ SATPS data } gives good results at { TAIL ~ longer distances } , SATPS data is used when the distance is greater than or equal to the optical threshold
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH