Hello,

Randall Pratt posted a message in the psn list some time ago
giving this link:

http://mit.midco.net/rpratt/images/Calibration%20using%20free%20Programs.pdf

it may be helpful in this discussion.

>  If Seismowin works with pole/zero manipulations, as is customary in the
>professional world; then it is an 'overkill' with too much attention to issues
>that are unnecessary.  The correction of the FFT to accommodate the transfer function

When I started to work in the seismological field I found that was no 
Windows software to accomplish the function that RESP and SURVEY modules 
of SEISMOWIN do.
I started to work with SEISAN (University of Bergen) which is rather 
complete Windows seismic analysis. But it was based on DOS code written 
in Fortran and with limitations to essentials.
Of course is common practice in "real" seismology to accomplish all this 
de-co/nvolutions using (just to mention one) SAC.

I also realized that VERY few people knows this process outside the 
seismologists group, especially in Italy... :-(
In seismology is also common practice to combine different element in a 
seismic station. For example in the Taurus (Nanometrics) digitizer you 
may connect from a 1Hz geophone to a BB 120 s Trillium sensor.

Working with Bergen University I learned people in latin america or 
anyway in developing countries, where there is no a large budget for 
earthquake monitoring (if any), they may found practical to use this or 
that geophone or sensor, sometime homemade.

So a tool to speedup the description of the transfer function of a 
seismic system was attractive. After 2008 when we introduced this tool 
to Norsar, University of Bergen and GFZ (Potsdam) this tool has been 
exteemed even if not used (they was already using different tools for 
the same purpose) for the ease of use. In what i know after this some 
other GUI born for the same purpose even if i don't remember exactly 
what they are.

The RESP module of Seismowin is easy because it works all around Poles 
And Zeroes. Giving 2 or 3 transfer function in PaZ you can put all in 
the same pot and the combined transfer functions comes out.
 From PaZ you can compute a bode-plot with Frequency, Amplitude and 
Phase (also called FAP) table and make the deconvolution in the 
frequency domain which is also quite straightforward.

RESP handles with ease a database of sensors, a database of 
amplifiers/filters and a database of digitizers.
These three elements can be combined to obtain a PaZ and FAP in the 
three domains of Displacement/Acceleration/Velocity.
So knowing your start function you can get any other measurement unit 
using a single click.

You may enter virtually any kind of sensor using natural parameters 
(like Generator constant, damping and eigenfrequency)
OR if you know the PaZ you enter that ones.
Many commercial sensors (like Nanometric, Lennartz etcc...) provides in 
the certificate of calibration Poles and Zeroes only.

I am agree the process can be simplified assuming some parameters at 
input and some desired output. But with RESP you can do almost all you 
need at any combination of instrument.

The RESP file generated by the RESP software can be entered in the 
SURVEY module and associated to a waveform. Then the waveform can be 
de-convolved with the respfile and bringed to any needed relative 
measurement unit and plotted with several FFT options.

We have limited documentation about it but i can try to put something 
together like a tutorial.

best regards


-- 
Mauro Mariotti
http://www.infoeq.it
http://www.sara.pg.it

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