Randall,

OK, I guess.

If I have a problem, I think I might prefer to=20
take issue with something different, and that is=20
the use of the terminology "Acceleration Power=20
Spectral Density" to label these noise plots.

As you had pointed out, they are, at best,=20
"Acceleration Specific-Power Spectral Density" as=20
we have no knowledge of mass.  In fact if I=20
wanted to be really precise I might prefer to=20
call it "Acceleration-Squared Spectral=20
Density".  I think the term "Power" may possibly=20
have originated in this context from our habit as=20
engineers of frequently labeling most anything=20
which is the square of a first-order variable as=20
"Power", regardless of its true physical nature.

Although it may be reasonable to call it PSD,=20
(Physical) Power Spectral Density, I think it is=20
not.  As ASSD, m^2/sec^4 per Hz would indeed be the proper units.

Regards,
Brett

At 12:35 PM 7/13/2012, you wrote:
>Brett,
>        What you mention has been presented to=20
> me by the professional seismologists; however,=20
> it is not correct, for the following reason:
>Any density function always has a =91per=92 quantity=20
>associated with it=ADfor example per Hz or per=20
>octave or per some fraction of a decade, such as=20
>1/7th (as in the celebrated work of Jon Berger,=20
>whose units are correct at m^2/s^3 /( 1/7th decade).




__________________________________________________________

Public Seismic Network Mailing List (PSNLIST)

To leave this list email PSNLIST-REQUEST@.............. with 
the body of the message (first line only): unsubscribe
See http://www.seismicnet.com/maillist.html for more information.