Fujitsu MHW2040AC User Manual download pdf (Page 67)

4.6 Read/write Circuit

(3) FIR circuit

This circuit is 10-tap sampled analog transversal filter circuit that equalizes the

head read signal to the Modified Extended Partial Response (MEEPR) waveform.

(4) A/D converter circuit

This circuit changes Sampled Read Data Pulse from the FIR circuit into Digital

Read Data.

(5) Viterbi detection circuit

The sample hold waveform output from the flash digitizer circuit is sent to the

Viterbi detection circuit. The Viterbi detection circuit demodulates data according

to the survivor path sequence.

4.6.4 Digital PLL circuit

The drive uses constant density recording to increase total capacity. This is

different from the conventional method of recording data with a fixed data transfer

rate at all data area. In the constant density recording method, data area is divided

into zones by radius and the data transfer rate is set so that the recording density of

the inner cylinder of each zone is nearly constant. The drive divides data area into

30 zones to set the data transfer rate.

The MPU set the data transfer rate setup data (SD/SC) to the RDC that includes

the Digital PLL circuit to change the data transfer rate.

C141-E258 4-11

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Fujitsu MHW2040AC User Manual Page 67