A microprocessor-based method for the measurement of speed and speed variation of low-speed drives

A digital method for the accurate measurement and display of speed and speed variation of low-speed drives is described. The method is based on the use of an incremental shaft encoder in association with an accurate crystal oscillator. The speed variations can be detected to within one thousandth of the time taken for one revolution of the drive shaft. The speed variation, along with its time of occurrence, is stored on the RAM and can be printed by a serial printer or can be stored on the hard disc of a personal computer.