Browse Prior Art Database

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

Publishing Venue

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

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 3

  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.

1

[This page contains 2 pictures or other non-text objects]

Page 2 of 3

(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

2

[This page contains 2 pictures or other non-text objects]

Page 3 of 3

aborted by HDC(hard disk controller) to prevent phase shift. And when
reading data, TES value is useful to set proper data frequency for
data channel.

(Fig-3) feed back operation of TES

3

[This page contains 2 pictures or other non-text objects]