Thermal asperity compensation for PRML data detection
AssigneeInternational Business Machines Corporation
InventorsRichard L. Galbraith, Gregory J. Kerwin, Joey M. Poss
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Abstract
Apparatus and method of thermal asperity compensation are provided for data detection in a partial-response maximum-likelihood (PRML) data channel. The PRML data channel includes an analog to digital converter (ADC) having a normal operating range and a filter, gain and timing control coupled to the ADC. When a thermal asperity is detected, a thermal asperity recovery mode is established responsive to the detected thermal asperity. The gain and timing control are held and the normal operating range of the ADC is adjusted responsive to the thermal asperity recovery mode. Also an AC coupling pole frequency is elevated responsive to the thermal asperity recovery mode.
Claims17
A method of thermal asperity compensation for data detection in a data channel including an analog to digital converter (ADC) having a normal operating range, filter, gain and timing control coupled to the ADC, said method comprising the steps of:
- detecting a thermal asperity;
- establishing a thermal asperity recovery mode responsive to said detected thermal asperity;
- holding the gain and timing control responsive to said thermal asperity recovery mode;
- and
- adjusting a normal operating range of the ADC responsive to said thermal asperity recovery mode.
Apparatus for thermal asperity compensation for data detection in a partial-response maximum-likelihood (PRML) data channel including an analog to digital converter (ADC) having a normal operating range, filter, gain and timing control coupled to the ADC, said apparatus comprising:
- means for detecting a thermal asperity;
- means for establishing a thermal asperity recovery mode responsive to said detected thermal asperity;
- means for holding the gain and timing control responsive to said thermal asperity recovery mode;
- and
- means for adjusting a normal operating range of the ADC responsive to said thermal asperity recovery mode.
A direct access storage device of the type including a partial-response maximum-likelihood (PRML) data channel comprising:
- a housing;
- at least one disk mounted in said housing for rotation about an axis and having at least one disk surface for storing data;
- transducer means mounted for movement across said disk surface for reading and writing data to said disk surface;
- an analog to digital converter (ADC) coupled to said transducer means for converting an analog input signal to digital sample values within a normal operating range;
- filter, gain and timing control means coupled to said ADC for controlling the ADC;
- means coupled to said ADC for threshold comparing said digital sample values to detect a thermal asperity;
- means for establishing a thermal asperity recovery mode responsive to said detected thermal asperity;
- means for holding the gain and timing control means responsive to said thermal asperity recovery mode;
- and
- means for adjusting said normal operating range of said ADC responsive to said thermal asperity recovery mode.
Dependencies are inferred from the claim text.