Which of the following describes an optical shaft encoder?

An optical shaft encoder is an electromechanical device used to translate the angular position or motion of a rotating shaft into digital electronic signals. They are commonly found behind the main tuning dial on modern amateur radio transceivers. The device works by placing a patterned wheel (a disc with alternating transparent and opaque segments) between a light source, like an LED, and an optical detector. As the shaft rotates, the wheel repeatedly interrupts the light beam, generating a series of digital pulses that a microprocessor uses to determine the shaft's rotational speed and direction. Distractors involving RTTY signals, optical computing, or analog beam strength measurements describe completely different technologies that do not relate to mechanical rotation detection.