max 2 is a u201c high u201d signal the then current operating frequency is determined to be above the vibratory conveyor 39 s resonant frequency step 636 alternatively if the value of the periodic digitized signal 702 at max 2 is a u201c low u201d signal the then current operating frequency is determined to be below the resonant frequency of the vibratory conveyor if a u201c high u201d to u201c low u201d transition is detected at max 2 the then current operating frequency is determined to be equal to the resonant frequency of the vibratory conveyor and the control process returns to step 604 for the generation of a current switch enable signal 714 that is equivalent to the previously generated enable signal however if the operating frequency of the vibratory conveyor is determined to be above the resonant frequency then the extent to which the operating frequency exceeds the resonant frequency is determined by comparing the phase of the periodic digitized signal 702 and the phase of the current switch enable signal 714 used to generate the current vibration motion signal the phase difference between these two signals is determined at step 642 and the default count number stored in the volatile memory 322 in the counter 300 will be incremented by an amount equal to.