PSN-L Email List Message

Subject: Re: Newbie trying to get started
From: Steinar Midtskogen steinar@.............
Date: Sat, 21 Jun 2008 09:06:47 +0200


>        You seem to be trying to do things the hard way!

It is also a good way to learn how things work, so I'm willing to make
a try.

>        The SEP box is designed to plug directly into almost any old
> PC running windows! You download the AmaSeis data logging and
> analysis software from http:
> // This gives you a WHOLE
> SUITE of dedicated seismic programs, including both low and high
> pass digital filters, FFT analysis and a lot more! The hard work has
> already been done for you!

I guess, but it is the x86 Windows part which is my problem.  True, I
can probably get a 20 year old Windows PC for free somewhere, though
it will still add to the electricity bill (wouldn't a PC with moving
parts, i.e. harddisk and fans, nearby the seismometer cause some
vibrations?) and it would take up even more space in the basement
storeroom (where I have the seismometer) which I don't really have.

My real concern is probably that I don't like to run software which
I'm unable to modify to my needs.  No source code = no control.

Anyway, the piece of code for reading the data was trivial, just a few
lines of C code.  And gnuplot does the plotting job for me, at least
the plotting that can be done automatically for a web page.  All this
was done in a few hours.

So I think the only thing I'm missing is the filter.  Does any seismic
programs come with source code?

But I'll have a look at AmaSeis anyway, which might be useful for
manual analysis of seismic events.  If I make my logger program store
raw data in a way AmaSeis can read it, I don't need to run AmaSeis on
my datalogger.  My regular PC is an AMD64 running Linux, but chances
that AmaSeis will run on it using Wine should be good.

I did make a very simple filter:

    output[i] = output[i-1] + alpha * (input[i] - output[i-1]);

and experimented with different values for alpha, but I suspect that
this filter is too soft.


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