Method and apparatus for providing adaptive drive-level compensation for amplitude and BER loss due to media thermal decay

An apparatus comprising:

• a disk surface having information stored thereon as magnetic transitions, the magnetic transitions being susceptible to thermal decay;
• a head for reading the information from the disk surface, wherein said head is biased by a bias current;
• means for determining a value related to the thermal decay of the magnetic transitions;
• and,
• means for increasing the bias current to compensate for the thermal decay of the magnetic transitions if the value indicates that the thermal decay has reached an unacceptable level.

A method comprising the steps of:

• providing a disk surface having information stored thereon, the information being stored as magnetic transitions that are subject to thermal decay;
• providing a head for reading said information;
• writing a high frequency reference sector on the disk surface;
• writing a BER reference sector on the disk surface;
• writing a high frequency normalization sector on the disk surface;
• writing a BER normalization sector on the disk surface;
• measuring initial values of the high frequency reference sector and the BER reference sector;
• storing the initial values of the high frequency reference sector and the BER reference sector in memory;
• measuring initial values of the high frequency normalization sector and the BER normalization sector;
• storing the initial values of the high frequency normalization sector and the BER normalization sector in memory;
• rewriting the high frequency normalization sector and the BER normalization sector upon expiration of a specified amount of time;
• measuring values of the high frequency normalization sector and the BER normalization sector upon expiration of the specified amount of time;
• determining a high frequency normalization factor and a BER normalization factor using the initial values of the high frequency normalization sector and the BER normalization sector and the values of the high frequency normalization sector and the BER normalization sector measured upon expiration of the specified amount of time;
• measuring values of the high frequency reference sector and the BER reference sector upon expiration of the specified amount of time;
• adjusting the values of the high frequency reference sector and the BER reference sector measured upon expiration of the specified amount of time using the high frequency normalization factor and the BER normalization factor;
• and,
• determining whether the adjusted values of the high frequency reference sector and the BER reference sector are within predetermined specifications related to the amount of thermal decay.

A method comprising the steps of:

• providing a disk surface having information stored thereon, said information being written as magnetic transitions which are subject to thermal decay;
• providing a head for reading said information, wherein said head is biased by a bias voltage;
• determining a value related to the thermal decay of the magnetic transitions;
• and,
• increasing the bias voltage to compensate for the thermal decay of the magnetic transitions if the value indicates that the thermal decay has reached an unacceptable level.