IBM IC25N020ATDA04 - Travelstar 20 GB Hard Drive - Nonoperating Shock 6.7 Acoustics; Sound Power Level; Figure 36. Weighted Sound Power

6.7 Acoustics
6.7.1 Sound power level
The criteria of A-weighted sound power level are described below.
Measurements are to be taken in accordance with ISO 7779. The mean of the sample of 40 drives is to
be less than the typical value. Each drive is to be less than the maximum value. The drives are to meet
this requirement in both board down orientations.
2.9
2.4
2.7
2.1
All other models
3.3
2.6
3.1
2.4
30 GB and 20 GB models
3.8
2.7
3.5
2.5
48 GB model
Operating
Idle
Operating
Idle
Maximum
(Bels)
Typical
(Bels)
A-weighted Sound Power
Figure 36. Weighted sound power
The background power levels of the acoustic test chamber for each octave band are to be recorded.
Sound power tests are to be conducted with the drive supported by spacers so that the lower surface of
the drive is located 25±3 mm above the chamber floor. No sound absorbing material shall be used.
The acoustical characteristics of the disk drive are measured under the following conditions:
Mode definitions
Ÿ Idle mode — Power on, disks spinning, track following, unit ready to receive and respond to
control line commands
Ÿ Operating mode — Continuous random cylinder selection and seek operation of the actuator with
a dwell time at each cylinder. Seek rate for the drive is calculated by the following formula:
Ns = 0.4/(Tt + T1)
where:
Ns = average seek rate in seeks/s
Tt = published seek time from one random track to another without including rotational
latency
T1= equivalent time, in seconds, for the drive to rotate by half a revolution
Travelstar 48GH, 30GN & 15GN hard disk drive specifications
40