Sensor-less DCM-MotionTechnology relies on the ‘build-in’ encoder signals generated by any rotating, brush commutated  electric DC motor (BDC motor) to detect and count motor motion.
It is well known that when a BDC motor rotates voltage transients are induced on the power supply wires to the motor.

These transients are generated by the rotating motor whether it is powered or not. They have traditionally been considered unwanted noise signals and as such are often suppressed by using appropriate filters in many motor applications.