on the corresponding scan plane if the value of the interval count register is equal to or greater than the quiescent register value activity is said to be present on the corresponding scan plane if the quiescent register value is less than its associated interval count register value the quiescent register value may be modified to reflect the lowest value of its associated interval count register in order to take into account different characteristics of individual scan planes such as their position and angle with respect to a scan window fig4 fig4 a 4b and 4 c collectively is a flowchart illustrating a method 400 for determining the direction of movement of an object in accordance with the present invention at step 405 the method checks whether a monitor indicator is set this indicator is used to indicate that a pair of scan planes have sensed activity in a previous revolution of motor 230 this step 405 is used in order to make at least two samples of activity on a particular scan plane pair a comparison of at least two samples of activity allow for the method to deduce the direction of a moving object as will be discussed below if the monitor indicator is not set a first sample has not yet been established thus method 400 proceeds to step 410 where activity for each scan plane pair is determined as.