Constant Angular Velocity

Constant Angular Velocity (CAV) refers to how information is written to or read from a rotating data disk. A typical example can be seen in one of the differences between an LP record and a compact audio disc (CD). With an LP, the disc always spins at the same angular rate (CAV) of 33⅓ rpm, so the surface of the record groove passes the needle at slower linear rate as the needle moves toward the center of the disc. Whereas, with a CD, the motor speed decreases from 495 to 212 rpm as the read head moves away from the center to keep the disc moving past the read head at a constant linear velocity (CLV).