Method and apparatus for accurate measurement of imaging surface speed in a printing apparatus

According to aspects of the embodiments, there is provided methods and apparatus for sensing the movement of a moving surface by utilizing a plurality of reference patterns positioned on the surface, using the precision of the ROS Start of Scan Clock, and the uses of encoder and MOB sensors. The plurality of reference patterns are placed a known number of scanlines apart. The MOB sensor and encoder measure the distance between reference patterns. Increase accuracy is achieved by sampling the encoder signal with the ROS Master Clock and calculating a fractional encoder count at the first and last encoder counts of the measurement. The use of fractional encoder counts provides a speed measurement with greater tolerance for variations in encoder dimensions and belt thickness.