Rotational vibration compensation using a dedicated surface with a constant frequency pattern

摘要

An apparatus and method for minimizing the effects of rotational vibration upon a disc drive having first and second heads supported adjacent first and second disc recording surfaces, respectively. A frequency modulation (FM) demodulator generates a rotational velocity signal indicative of application of rotational vibration to the base deck in relation to changes in frequency of a readback signal generated from a circumferentially extending frequency pattern written to the first disc recording surface at a constant frequency. A servo circuit controllably positions the first and second heads in response to servo information stored on the second disc recording surface and the rotational velocity signal from the FM demodulator. The servo circuit further interrupts a data transfer operation between the second disc recording surface and a host device when a magnitude of the rotational velocity signal exceeds a predetermined threshold.