Abstract: An electrical bi-directional motion sensing and clocking system is disclosed for identifying the relative sense and magnitude of movement experienced by a moving body. The corresponding relative motion of a target past a pair of sensor units produces a pair of input signal pulses from the sensors for each increment of movement experienced by the moving body. Each occurrence of such a pair of input pulses is recorded and gives rise to a clock output signal upon the recorded occurrence of both input signals. The relative occurrence sequence of the two input signals is also recorded and utilized to provide a respectively corresponding output representing the direction of body movement to be associated with the detected movement increment. The system is arranged so as to suppress spurious output signals which might otherwise be generated when the relative sequence of input signals is reversed at any arbitrary point in the cycle of detecting an increment of motion.