PSN-L Email List Message

Subject: Re: WinQuake question for Larry
From: "Geoffrey" gmvoeth@...........
Date: Sat, 28 Mar 2009 09:20:38 -0700


Hello You Math experts;

By Spectral Density are you by chance
figuring the area under the curve ?
Which I believe to be a calculus thingy ?

Regards;
geoff

----- Original Message ----- 
From: "Brett Nordgren" 
To: 
Sent: Saturday, March 28, 2009 6:54 AM
Subject: Re: WinQuake question for Larry


> Larry,
> 
> Many thanks.  I downloaded the (very) new WinQuake and now have the FFT 
> data exported.  I think that it is exactly what I was looking for.
> 
> Now to get educated on spectral density stuff.
> 
> Brett
> 
> 
> At 11:29 PM 3/27/2009 -0700, you wrote:
>>Brett,
>>
>>Brett Nordgren wrote:
>>>Larry,
>>>When I do an FFT on a PSN file, the result is normalized to fill the 
>>>screen vertically.  Is there any way to extract the normalization factor 
>>>so that I could use the results to generate a calibrated noise spectrum?
>>
>>Not within WinQuake. With the current version of WQ you can export the raw 
>>FFT data so you can analyze the FFT data using other programs like MATLAB 
>>or Excel. To do this create an FFT Window and use the File / Export menu 
>>items. The resulting file will look like this:
>>
>>Freq,Real,Imaginary,Magnitude
>>0.000190735,-0.0925326,0.182551,0.409328
>>0.00038147,-0.17057,-0.0860256,0.38207
>>0.000572205,0.110639,-0.0927722,0.288774
>>0.000762939,-0.0952175,0.178415,0.404466
>>0.000953674,-0.15761,-0.0518402,0.331834
>>0.00114441,0.0554941,-0.136885,0.295412
>>0.00133514,0.02051,0.0920337,0.188583
>>...
>>
>>The first number is the frequency then the real and imaginary numbers from 
>>the FFT function and then the magnitude. The magnitude is calculated using 
>>the following C code
>>
>>mag = hypot(Real[i] , Imag[i] );
>>
>>Regards,
>>Larry Cochrane
>>Webtronics
> 
> 
> __________________________________________________________
> 
> Public Seismic Network Mailing List (PSN-L)
> 
> To leave this list email PSN-L-REQUEST@.............. with 
> the body of the message (first line only): unsubscribe
> See http://www.seismicnet.com/maillist.html for more information.
>
__________________________________________________________

Public Seismic Network Mailing List (PSN-L)


[ Top ] [ Back ] [ Home Page ]