Asynchronous Maximum Likelihood (ML) Detection Of Servo Repeatable Run Out (RRO) Data

A servo sector contains a preamble, servo address mark (SAM), Gray data, burst demodulation fields, a DC erase section and then repeatable run out (RRO) field. The RRO field consists of a RRO address mark (RROAM, same for every sector) and RRO data. The servo controller processes the RRO field to compensate for effects such an off center spindle rotation. We discuss the detection reliability of the RRO field, not how it is used for RRO compensation. We (i) propose a maximum likelihood (ML)asynchronous detection technique for coded servo RRO data (ii) quantify the detection.