[SAC-HELP] Instrument response removal

[Ivan Lokmer]

Dear Colleague,

I hope that I am at the right address to launch my question.
I was using SAC polezero option recently to remove the instrument 
response from my data and to add it to synthetics.
However, I realized that this option is acting as a 2-pass acausal 
filter. AS the actual seismometer filters the ground motion as 1-pass 
causal filter, it seems to me that it is impossible to recover actual 
ground motion by using this option.
It is not very obvious with very band limited data, but it is more than 
obvious for the data with static shift, where the waveform is changed 
before time 0 (which is impossible for any physical device including 
seismometer).
Do you maybe know if there's any option in SAC that will add/remove 
instrument's response as of the actual physical device (causally)?

Thank you in advance for your answer
A great job is done with all the manuals and software. Thanks for that

Kind regards,

Ivan

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Ivan Lokmer
Seismology and Computational Rock Physics Lab.
Geophysics Group 
School of Geological Sciences
University College Dublin
Belfield
Dublin 4
Ireland

Phone: +353 1 7162079
Fax:   +353 1 2837733
Mobile:+353 87 2553638
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