4.7 Servo Control

4.7.3 Servo frame format

As the servo information, the IDD uses the phase signal servo generated from the gray code and servo EVEN and ODD. This servo information is used for positioning operation of radius direction and position detection of circumstance direction.

The servo frame consists of 5 blocks; write/read recovery, servo mark, gray code, Burst EVEN1, Burst ODD, Burst EVEN2, and PAD. Figure 4.8 shows the servo frame format.

Write/read

recovery

Servo mark

Gray code

Burst

EVEN1

Burst

ODD

Burst

EVEN2

Post code (particular models only)

PAD

Figure 4.8 Servo frame format

(1) Write/read recovery

This area is used to absorb the write/read transient and to stabilize the AGC.

(2) Servo mark

This area generates a timing for demodulating the gray code and position- demodulating the burst signal by detecting the servo mark.

(3) Gray code (including sector address bits)

This area is used as cylinder address. The data in this area is converted into the binary data by the gray code demodulation circuit

(4) Burst Even1, Burst Odd, Burst Even2

These areas are used as position signals between tracks and the IDD control so that target phase signal is generated from Burst Even and Burst Odd.

(5) Post code (particular models only)

This area is used for the precise correction of the servo information which is recorded on the media.

(6) PAD

This area is used as a gap between servo and data.

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Fujitsu MHW2040AC, MHW2060AC manual Servo frame format
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MHW2060AC, MHW2040AC specifications

The Fujitsu MHW2040AC and MHW2060AC are notable hard disk drives (HDDs) that have been widely used in various computing applications, especially in laptops and compact devices. These models are part of Fujitsu's commitment to providing reliable storage solutions that meet the demands of modern computing.

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