Patent ID: 7482774

Claim:
A movable barrier operator comprising: a movable barrier movement sensor configured to sense movement of a barrier and effect signals which reflect movement of the barrier upstream and downstream; a counter that is responsive to the signals effected by the barrier movement sensor to provide a corresponding count having a plurality of count values which indicate a position of a barrier; at least one passpoint signal generator which effects at least one passpoint event from at least one fixed reference point between an open and closed position of the barrier and defines a location of at least one count zone defined by count values which are intermediate the full range of movement of the barrier and which count values are both upstream and downstream of the fixed reference point; a movable barrier position determiner that is responsive to the counter and the passpoint signal generator and which correlates the count of the counter with the passpoint event as the counter counts signals which reflect movement and the position of the barrier through the count zone, a count value being recalibrated from a passpoint event between the open and closed position of the barrier when an anticipated passpoint event between the open and closed position of the barrier does not correlate with a count value in the count zone as the barrier moves past the passpoint reference point between the open and closed position of the barrier such that a position of the barrier is indicated relative to a reference point that is intermediate the full range of travel of the barrier.