ASD vs PSD

[krue0101]

I am trying to convert some test specifications from ASD to PSD and make sure I am getting equivalent requirements.

Some research I have done say ASD is the same as PSD.

I don't know what to believe.

Could anyone help me out on this issue?

Your experience would be appreciated.

Thanks

Joe

 

[IRstuff]

What are the units of the ASD? if it's power per something, then they're the same.

TTFN

Eng-Tips Policies FAQ731-376

 

[CESSNA1]

KRUE101: ASD stands for "Acceleration Spectral Density" and PSD stands for "Power Spectral Density" If you are using vibration data ASD and PSD are the same. PSD was used in the acoustics world many years ago and has been carried over into vibrations world. The units of ASD and PSD are G^2rms/Hz. In vibrations PSD is used by default.

Regards
Dave

 

[BobM3]

Dave -

Are you sure ASD doesn't stand for "Auto Spectral Density"?

 

[IRstuff]

Hunh, I thought it was amplitude spectral density ;-)

TTFN

Eng-Tips Policies FAQ731-376

 

[CESSNA1]

BOBM3 and others: Your probably right. I often refer to it as the Acceleration Spectral Density (because that is what it is), BUT the "Auto Spectral Density" is identical to the "Power Spectral Density"

Regards
Dave

 

[BobM3]

I'm not sure about that Dave. An Auto Spectral Density can be generated from any time history such as an acceleration signal or a velocity signal or a voltage signal, etc. The units of the ASD, as TTFN asked about, would tell us what Joe has.