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# Timing Error Signal to detect rotation speed change and the method to correct data read frequency

IP.com Disclosure Number: IPCOM000014019D
Original Publication Date: 2001-Dec-30
Included in the Prior Art Database: 2003-Jun-19
Document File: 3 page(s) / 75K

IBM

## Abstract

Timing error signal(TES) is effective to protect a phase shift error caused by writing data during improper disk rotation speed, By applying TES in data pattern, it becomes to be possible to detect spindle jitter and phase shift error can be prevented by aborting write data when TES value is over the criteria. Fig-1 shows a construction of TES. (Fig-1) construction of TES TES value can be calculated from burst data sampled in A/B/C/D window by following formula. TES generation algorithm if (C-D) (C+D)*e ifA>B

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Timing Error Signal to detect rotation speed change and the method to correct data read frequency

Timing error signal(TES) is effective to protect a phase shift error
caused by writing data during improper disk rotation speed, By applying
TES in data pattern, it becomes to be possible to detect spindle jitter
and phase shift error can be prevented by aborting write data when TES
value is over the criteria. Fig-1 shows a construction of TES.

(Fig-1) construction of TES

TES value can be calculated from burst data sampled in A/B/C/D window
by following formula.

=== TES generation algorithm ===
if (C-D) < (C+D)*e
ifA>B

TES = +infinite
else

TES = -infinite
endif
else

TES = (A-B)/(C-D)
endif
where e = given small value (f.e. e=0.1)

As shown in Fig-2, TES value can detect the change of rotation speed.

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(Fig-2) TES v.s. rotational jitter

Fig-3 shows the example of feedback control for Write/Read operation.
When TES value becomes over the criteria, then write operation is

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