(54) SYSTEMS, APPARATUS, AND METHODS TO DETERMINE THERMAL DECAY CHARACTERIZATION FROM AN EQUALIZED SIGNAL-TO-NOISE RATIO OF A MAGNETIC DISC DRIVE DEVICE
(75) Inventors: Edmun Chian Song Seng, Singapore (SG); UttHeng Kan, Singapore (SG)
(73) Assignee: Seagate Technology LLC, Scotts Valley, CA (US)
( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 421 days.
(21) Appl. No.: 10/172,515
(22) Filed: Jun. 14, 2002
(65) Prior Publication Data
US 2003/0016461 Al Jan. 23, 2003
Related U.S. Application Data
(60) Provisional application No. 60/302,199, filed on Jun. 29, 2001.
(51) Int. CI.
G11B 5/02 (2006.01)
(52) U.S. CI 360/25; 702/69; 360/31;
360/53; 360/66; 360/68; 360/69; 360/78.04;
360/78.06
(58) Field of Classification Search 702/69;
360/25, 31, 53, 66, 68, 69, 78.04, 78.06 See application file for complete search history.
(56) References Cited
U.S. PATENT DOCUMENTS
4,905,102 A * 2/1990 Schulz 360/46
The thermal decay of data written to a magnetic mass storage medium is determined by measuring and analyzing the time-domain equalized-signal-to-noise ratio (ESNR) and equalized signal-to-total-distortion noise ratio (ESTDR) of written data. In some embodiments, a test track and a reference track are initialized from data. Subsequently, the reference track is re-initialized from the test data, and the time-domain ESNR and/or ESTDR measurements are made of the test track and the reference track, at predetermined time intervals. Later, the time-domain ESNR and ESTDR measurements are analyzed to determine the thermal decay of the data written. In another embodiment of the present invention, the ESNR and/or ESTDR measurements includes reading the data through a non-return-to-zero bus in phases, in which the phases are selected in sequence.
23 Claims, 11 Drawing Sheets
