Datasheet

7.7 Acoustics
7.7.1 Sound power level
The criteria of A-weighted sound power level is described as follows.
Measurements are to be taken in accordance with ISO 7779. The mean of 40 drives is to be less than the
typical value. Each drive is to be less than the maximum value. Drives are to meet this requirement in
both board down orientations.
2.52.2Operating
2.42.1Idle
MaximumTypical
A-weighted sound power
(Bels)
Figure 19. Sound power levels
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 at 25±3 mm height from the chamber floor. No sound absorbing material is used.
The acoustical characteristics of the disk drive are measured under the following conditions:
Mode definition
y Idle mode
Power on, disks spinning, track following, unit ready to receive and respond to control line command
y Operating mode
Continuous random cylinder selection and seek operation of actuator with a dwell time at each
cylinder. Seek rate for the drive can be calculated as follows:
Ns = 0.4 / (Tt + T1)
where
Ns = average seek rate in seeks/second
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
7.7.2 Discrete tone penalty
Discrete tone penalties are added to the A-weighted sound power (LW) with the following formula only
when determining compliance:
LWt(spec) = LW + 0.1Pt + 0.3 < 4.0 (Bels)
where
LW = A-weighted sound power level
Pt = Value of discrete tone penalty [= dLt–6.0 (dBA)]
dLt = Tone-to-noise ratio taken in accordance with ISO 7779 at each octave band
Hard disk drive specification for DSCM-11000/-10512/-10340
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