IBM DJSA-210 Hard Drive Specifications - Page 51

Acoustics, 7.1 Sound power level, 7.2 Discrete tone penalty - specs

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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. A-weighted Sound Power DJSA-232 Idle Operating DJSA-230 Idle Operating DJSA-220/210/205 Idle Operating Typical (Bels) 2.5 3.5 2.8 3.5 2.8 3.3 Maximum (Bels) 2.7 3.8 3.4 3.8 3.4 3.6 Figure 31. 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 be located 25±3 mm above from 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 ! Idle mode-Power on, disks spinning, track following, unit ready to receive and respond to control line commands. ! 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 shown below. ! 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 6.7.2 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) Lw = A-weighted sound power level Travelstar 32GH/30GT/20GN hard disk drive specifications 37

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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.
3.6
3.3
Operating
3.4
2.8
Idle
DJSA-220/210/205
3.8
3.5
Operating
3.4
2.8
Idle
DJSA-230
3.8
3.5
Operating
2.7
2.5
Idle
DJSA-232
Maximum (Bels)
Typical (Bels)
A-weighted Sound Power
Figure 31. 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 be located 25±3 mm above from 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
!
Idle mode—Power on, disks spinning, track following, unit ready to receive and respond to control
line commands.
!
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 shown below.
!
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
6.7.2 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)
Lw = A-weighted sound power level
Travelstar 32GH/30GT/20GN hard disk drive specifications
37