dB per octave spec with a ASD curve 2

[Tunalover]

When someone specs 2dB or -2dB 'per octave' in the context of acceleration spectral density, what does it mean graphically?


Tunalover

 

[GregLocock]

If you plot db versus log frequency it should drop at 2 dB per doubling of frequency, in a straight line.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Tunalover]

Greg-
dB is a log of a ratio...but what is the ratio in this case?
Tuna


Tunalover

 

[GregLocock]

Referenced to your reference value (!). Won't actually make any difference to the slope.

Possible reference value for an asd would be 1 g^2/Hz but you'd get very negative values. Don't get caught out by the difference between 10 log and 20 log for your dBs.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[tomirvine]

I have posted a conversion utility for dB/octave calculations at:

http://www.vibrationdata.com/dboct.exe

Tom Irvine

http://www.vibrationdata.com

 

[Tunalover]

Thanks Tom Irvine!


Tunalover