A unit of absolute rotary position encoding, where the angular range of encoding is matched to the number of poles of an electrical motor it is intended that the encoder is to be attached to. The electrical motor is suitably a brushless DC motor. This provides unique rotational position values only through an angle corresponding to an angle between two consecutive poles to enable control/drive electronics to accurately and smoothly turn the rotor from standstill and at low speeds with varying loads applied to the motor.