PSN-L Email List Message

Subject: Re: Most Recent Discover Magazine pp66-67 WaterFall Display
From: "Geoffrey" gmvoeth@...........
Date: Sun, 8 Jul 2007 07:01:56 -0700

This program seems to not use data files
but wants you to build a custom A/D that
will be read by the program itself.
Not sure a sound card will take sample rates
as low as 20Hz because most sound hardware
has a capacitor input that rejects DC or freqs
below the sense of hearing.

It would be so nice to have this feature in Winquake to
do an Analysis of file data in TXT/8/12/16/24 bit form
or text form all you have to do is limit the frq
between Dc and 5 Hz or so and make atleast
1024 samples per spectrum line.

I have seen the routine in the library at ASU
to FFT and there seems to be several ways.
The best i like seems to result in the final
results with the number of samples to be worked
setting the resolution over the band.

These people who write these books on FFT are oriented
only to their own kind so if you do not know calculus or higher
transforming their ideas into a computer program is very difficult.

But I have in the past done this successfully myself.
On a very small scale with a VIC20 machine running 10MHz.

You need to take the first 1024 samples then make an imaginary
set from the same ones then do a butterfly operation
(some kind of fancy math) that results in a backward
spectrum with each sample now representing a frequency band.

Then you straighten out the results to get the low freq at the low
sample number position.

The final results is the freq range represented within the sample set chosen
and that would be line one.

Then you advance one sample in the data and do the same for the
next contiguous 1024 samples.

This is repeated until you have built a picture of your entire data file.

The sample rate determins the freq limits I think.

Why do not more people take an interest
in the math and programming and hardware
because seismology is just a fine specialty
and I think more serious PROs should take an
interest in fostering human interests in all lines of Science.

You got to be an MD or equiv before you can
get into forensic medicine ot Toxicology but this
Seismology stuff is non license stuff and great way to
learn many facets of science.

Please someone with Math background make us a
Basic Program like QBASIC or POWERBASIC
to do one line of FFT and I will take it from there
to make the whole program.

I did this once myself but did not record the final
program and would have to learn everything all over
again to do this program again.
A Burgler stole the VIC20 laptop with all my programs
several years ago so those programs are lost.

There is more to amateur stuff then just watching the waves
and building things with your hands. It is a great chance
to play general science and bring most everything together
to see how it works with NO MYSTRIES.

There seems to be effort to compartmentize information
in the USA because of its capitalistic nature forcing one
to become a college goon before you are able to
do anything academic. The truth of the matter
is to get a formal degree the system studies you as much
as you study your subject so there is no real privacy
or artisic freedom for the adventerous academic without
government awareness. The Counter Intelligence peoples
do not want Academic Freedom in the USA.
Even tho we are playing with this harmless passive seismology stuff.

I have come to realize that in some European Countries
they have laws amounting to NEPLEONIC LAW which basically
says everything is illegal except that which is specified by government.

These kinds of forces are what we up against even in this
relatively harmless area of seismology.

If there is no common place to get knowledge we must make it ourselves
even if it angers the powers that be.

It is no accident we can not find a simple BASIC FFT source code
with logic trees etc in laymen terms for our interest area.
Everyone is trying to keep secrets or make money.

For the sake of the evolution of science lets
please gather together a collection of utility programs
free for universal use in this PSN group.

I am assuming PSN means Public like WORLD PUBLIC and not just
California Public.

One LAST thing for NOW.
Black and White and shades of gray is by far the best for resolution and universal readability.
If a person is lucky to get a totally black and white monitor or green
you will see no sharper images than with such an analog electrostatic scanning device.
The military used to preferr these over color since it used to be all male
(for warships)
and males have the highest incident of color blindness.


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