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

[Arthur Snoke]

The relation you cite is based on a polexzero file that has been obtained 
by using RDSEED on a SEED volume for an event using that station.

If you have a polezero file, the documentation for that file will 
hopefully tell you how to interpret CONSTANT.  Others on the list may know 
the characteristics for your system and provide your answer.

On Fri, 28 May 2010, Danilo Domingos wrote:

> 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
> 
> 
>