I hate to say this.... but some of this stuff
really quacks me up :-)

I find it hard to translate this Montage of scientific data
into what I want to see.

GIVEN:
If you take a 1Hz geophone and plant it in a
relatively quiet place free from human artifacts,
you run the signal straight through filtering
out everything above 1/2 the sample frequency
as well as everything greater than 40 seconds of period.
You amplify the signal until noise is like +/- two counts
in a twelve or more bit A/D converter.
Then you record this Z channel data as RAW
single floating point 4 byte data.
Say its on the Colorado plateau??(spelling unsure)
OR Arizona basin range area ??

I should think such results would be regional in nature.
Help a person know if their system is functioning correctly.
After making such a data base of regional noise profiles
you should not need fancy equipment to calibrate your system
with meaningful values.

FIND:
The frequency profile exhibited from a FFT
ENERGY (FREQ(Y)/TIME(X))display or
waterfall ( three dimensional (time)Y/energy(MAG)/frequency (X)) display 

Communicating in English with people trained Outside
your own discipline is very difficult since basically
you do not speak the same language or have the same
meaning given the very same words.

I am just hoping you can understand me here.

But you are on the right track.

Thanks,
geoff


----- Original Message ----- 
From: "sismos" 
To: 
Sent: Friday, April 09, 2010 12:59 PM
Subject: Re: Question to Techno-Philes


> 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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> 
> 
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