Fujitsu MHY2100BH, MHY2160BH, MHY2200BH, MHY2250BH, MHY2120BH, MHY2080BH, MHY2060BH Servo frame format

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.

Basically, 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	Servo	Gray code	Burst	Burst	Burst	Post	PAD
recovery	mark		EVEN1	ODD	EVEN2	code
						(particular
						models
						only)
		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.

C141-E262 4-17