Changeover of counters in pulse generator with a numerical count discriminator

One generic approach to determine the angular speed and angular position measurements of a motor or a vehicle is by implementing pulse generator followed by a counter. Typically, the output-frequency of a pulse generator varies proportionally to the motor speed. The main purpose of a counter is to convert this frequency “modulated” (FM) signal to an amplitude modulated (AM) signal. In this paper, a methodology is proposed, similar to a method employed in communication systems, which accomplishes this conversion numerically. In particular, instead of digitizing the counter output, the pulse generator signal is digitized and passed to a “modified” count discriminator where the FM to AM conversion is numerically accomplished. As a result, one piece of hardware is dropped, and counter saturation problems are avoided. An experiment is conducted to illustrate the application of the proposed algorithm. Finally, the speed control of a DC servomotor is also included to validate the performance of this methodology