WOBBLE EXISTENCE JUDGING DEVICE, MEDIUM DISCRIMINATING DEVICE, WOBBLE EXISTENCE JUDGING METHOD AND MEDIUM DISCRIMINATING METHOD

摘要

A wobble existence judging device is provided with an amplitude correcting means which generates a wobble signal, in which amplitude of a prescribed frequency component is corrected to be substantially constant, from a radial push-pull signal by correcting the amplitude of a prescribed frequency component to be kept substantially constant and outputs a multiplying factor as a gain control signal for correcting the amplification of the prescribed frequency component. The wobble existence judging device is also provided with a judging means which judges existence of a wobble based on the minimum value of the multiplying factor indicated by the gain control signal.