Geoff,

I am not quite sure that I understand what you are looking for but maybe
this will help

Take a look at this which talks about the NLNM which is sort of a ideal
and impossible model for any one site.  As I understand it they chopped
up the thing by frequency and them picked the quiets place on earth and
made a composite

http://www.geophys.uni-stuttgart.de/oldwww/seismometry/man_html/node28.html

then take a peek at this article about power density functions

http://geohazards.cr.usgs.gov/staffweb/mcnamara/PDFweb/Noise_PDFs.html

and then take a look at what a PDF looks like for my station BRU2.  The
article below is very good and has some good examples of what you can
see on a PDF plot.

http://www.iris.edu/servlet/quackquery/pdfDrill.do?station=BRU2&yyyyDDD=2010.032&length=31&location=30&channel=HHZ&network=PA

For all this to be done the station need to be calibrated so that counts
or volts or whatever can be converted to real ground motion.  But is
give you a very good idea of how a whole station is working.  Some
station PDF are very interesting.  It is also easy to see daily and
seasonal variation at a station.  Most sites will be between the two
gray lines, the high noise and low noise models.

I the PDF of my station BRU2 you can see that between 1 Hz and 10 hz the
there is a high (light blue) probability that it is one of two noise
levels.  Mostly likely one is daytime and one is night time, in the of
the frequencies my station is mostly likely in a known place.  

Any instrument aberation would show up on a PDF.

We would all like a station like ISCO in an abandoned mine tunnel
station in Idaho Springs CO

I hope this helps a  little.

Angel








On Fri, 2010-04-09 at 11:02 -0700, Geoffrey wrote:
> Hello PSN;
> 
> I have been looking at your noise profiles and begin to wonder
> about technical specs for amateur hardware.
> 
> Can any of you tell/show me what the noise profile
> should look like coming from the ground, through
> velocity transducer, through anti-alized filtered hardware
> Through 12 bit A/D into single float raw data display using
> like Winquake FFT  for the following types of data:
> 
> 0. acceleration    inches/second^2
> 1. Velocity            inches/second
> 2. Displacement  inches
> 
> I invite you to create a representation of your
> ideas and draw them in paint or whatever program
> then send it to me as a BMP or JPG or GIF file
> as an attachment.
> 
> You do not need to show detailed squiggles just
> the general profile of what to expect.
> 
> It seems to me your hardware is overfiltering
> or your sample rates are wrong. Something
> does not look right to me in your various
> noise profiles but I cant put a finger on
> any of it. Possibly you are converting from
> other kinds of source data than RAW to make
> your PSN files.
> 
> Thanks Ahead of time, for your responses.
> regards,
> geoff
> 
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