[SAC-HELP] Help with polezero, transfer to vel and acc

[Danilo Domingos]

  Hello everyone!
 Ok, where to begin?
 I have to calculate the PGA (peak ground acceleration) of some
events, and to do that I have 2 options:
 1) Use the SAC function TRANSFER to convert the original
displacement data to acceleration.
 2) Manually convert the data to velocity (using seismometer and
digitizer parameters), and then differenciate to acc.
 Why is this 2nd option there?
 Because I've tried to understant how to build the POLEZERO file too
many times. The poles and zeros aren't a problem (I've found them in
the seismometer manual), but to find the constant value, I've seen a
lot of formulas. One of them is:
 CONSTANT = A0 * SensorGain * DigitizerGain
 where A0 is the "normalization factor". I can't find it in the
seismometer manual. Theese are the informations I have about
seismometer and digitizer:
 - Seismometer: KS2000 Geotech Instruments
 - Seismometer seismic output: 40V pp
 - Seismometer sensibility: 2000 v/m/s
 - Digitizer: SMART24 Geotech Instruments
 - Digitizer  LSB value for 40V pp: 3.271096e-6 V/count
 - Digitizer Gain: x 64 (multiplication)
 As far as I know, displacement data is given in counts
 Any ideas with the constant calculation? or should I try to
calculate acc manually with the conversion to velocity (using
parameters) and the differentiating?
 Thank you very much.
 ---------------------------------------------------------- 
 Danilo de Oliveira Domingos 
 University of São Paulo
 Brazil
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