Patent ID: 8810939

Claim:
A data storage system, comprising: a head; a drive mechanism for passing a medium aver the head; a controller electrically coupled to the head; logic encoded in or available to the controller for measuring a current position error signal; logic encoded in or available to the controller for calculating a standard deviation or a variance using the current position error signal sample; logic encoded in or available to the controller for calculating a kurtosis value, using the current position error signal sample or derivative thereof; logic encoded in or available to the controller for adjusting a threshold value using the kurtosis value; logic encoded in or available to the controller for comparing the standard deviation or variance to the threshold value; logic encoded in or available to the controller for enabling writing when the standard deviation or variance does not exceed the threshold value; logic encoded in or available to the controller for determining a stopwrite threshold based on a standard deviation or a variance at a current position error signal sample when the standard deviation or variance exceeds the threshold value; logic encoded in or available to the controller for determining whether the current position error signal sample exceeds the stopwrite threshold; logic encoded in or available to the controller for disabling writing when the current position error signal sample exceeds the stopwrite threshold; and logic encoded in or available to the controller for enabling writing when the current position error signal sample does not exceed the stopwrite threshold.