Read Circuit - Fujitsu MAH3091MC - Enterprise 9.1 GB Hard Drive Product/Maintenance Manual

8.6.3

Read circuit

After fixing the data output from the head IC to a certain level by Automatic Gain Control (AGC),
the Read circuit converts the waveform digitally by Analog to Digital Converter (ADC) circuit via
analog filter circuit. And then, after equalization by Finite Impulser Response filter (FIR filter),
being converted to logic signal by Viterbi detection circuit, convert into NRZ data by 32/34
decoding circuit, and then the Read circuit sends the data to buffer memory.
(1) AGC amplifier
The AGC amplifier automatically keeps the output amplitude level constant, even if the input
amplitude level changes. Even if the head output level changes with head characteristics and outer
or inner head position, the AGC amplifier output level is constant.
(2) Analog filter, ADC, FIR filter and Viterbi detection circuits
AGC amplifier output is demodulated in MEEPRML method as a total process through analog
filter circuit, ADC circuit, FIR filter circuit and Viterbi detection circuit.
(3) 32/34 RLL decoding circuit
The 32/34 RLL decoding circuit decodes the viterbi detection circuit output signal. This decoding
circuit reverse converts (scrambles) the pseudorandom pattern (created at write) into NRZ data.
The NRZ data is then fed to the upper-level circuit.
Table 8.1 MAJ3364 series, MAJ3182 series data frequency and recording density in each zone
Zone 0
0
Cylinder to
749
1F(MFRPS) 66.2
2F(MFRPS) 264.9
bpi 306,299
Zone 8
7,230
Cylinder to
8,389
1F(MFRPS) 55.7
2F(MFRPS) 222.8
bpi 346,912
MFRPS: Mega Flux Reversals Per Second
(*1) The value given in parenthesis is for MAJ3182 series.
8 - 8
1 2
750 1,500 2,180
to to
1,499 2,179 2,859
66.2 65.5
264.9 262.1 258.5
314,109 318,172 321,452
9 10
8,390 9,590 10,440
to to
9,589 10,439 11,199
53.2 51.7
212.8 206.9 200.9
350,784 355,909 359,425
C141-E103-02EN
3 4 5
2,860 4,040
to to to
4,039 5,034
64.6 62.7 61.4
250.8 245.5
325,710 331,309
11 12 13
11,200 12,370
to to to
12,369 13,199
50.2 48.1 46.2
192.4 184.9
367,219 370,280
6 7
5,035 6,030
to to
6,029 7,229
60.0 57.7
240.0 230.9
337,122 341,278
14 15
13,200 13,913
to to
13,912 14,791
(14,807)*1
44.7 42.9
178.8 171.5
373,934 379,202
(379,601)