Therefore, {HEAD ~ the user} may accurately set {TAIL ~ the motion threshold} using the current level as a reference, as shown in the drawings of the invention 
Therefore , { HEAD ~ the user } may accurately set { TAIL ~ the motion threshold } using the current level as a reference , as shown in the drawings of the invention
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH