Thread: Conversion to particle displacement and removing instrument response

Started: 2018-01-16 00:07:10
Last activity: 2018-01-16 23:52:38
Topics: SAC Help
James Whittaker
Conversion to particle displacement and removing instrument response
2018-01-16 00:07:10
Hi

I have some data recorded in particle velocity and I need to convert it to particle displacement and remove the instrument response. These are 30 Hz geophones used to capture high frequency microseismic data.

The script I have is :

read $f
rtrend
int
transfer from polezero subtype polesandzeros to none freqlimits 0 30 490 500
w append .comp

where my polezero file is a simple,

ZEROS 2
0 0
0 0
POLES 2
-41.47 183.88
-41.47 -183.88
CONSTANT 1

My concern is that I am converting to particle displacement twice in the process, firstly by integrated and then by removing the instrument response. It's not clear from the help files how to specify the from format before the to format in addition to the polezero file.

Thanks

James



Mr James Whittaker
Research Assistant / Cymrawd Ymchwil
Geoenvironmental Research Centre / Canolfan Ymchwil Geoamgylcheddol
School of Engineering / Yr Ysgol Beirianneg
Cardiff University / Prifysgol Caerdydd
Queen's Buildings / Adeiladau'r Frenhines
Newport Road / Heol Casnewydd
Cardiff / Caerdydd
CF24 3AA

Email / Ebost: whittakerj4<at>cardiff.ac.uk


  • Milton Plasencia
    Re: Conversion to particle displacement and removing instrument response
    2018-01-16 23:52:38
    Hi,

    To answer in short you can do:

    read $f
    rtrend (or rmean)

    transfer from polezero subtype polesandzeros to none freqlimits 0 30 490 500

    w append .comp


    where your polesandzeros will be:

    ZEROS 3

    0 0

    0 0

    0 0

    POLES 2

    -41.47 183.88

    -41.47 -183.88

    CONSTANT 1


    In this way you to obtain displacement directly,


    not is the same int and then removing the instrument response,

    int is in the time domain instead add a 0 in your response files is

    spectral integration.


    With 2 zeros and 2 poles you response curve have the following aspect:

    -------------------------------

    /

    /

    is open in high frequencies and you can set your freq. limits very high!!!


    HTH,


    Milton






    ----------------------------
    Milton Plasencia
    mplasencia<at>inogs.it


    On Tue, Jan 16, 2018 at 3:36 PM, James Whittaker <WhittakerJ4<at>cardiff.ac.uk>
    wrote:

    Hi



    I have some data recorded in particle velocity and I need to convert it to
    particle displacement and remove the instrument response. These are 30 Hz
    geophones used to capture high frequency microseismic data.



    The script I have is :



    read $f

    rtrend

    int

    transfer from polezero subtype polesandzeros to none freqlimits 0 30 490
    500

    w append .comp



    where my polezero file is a simple,



    ZEROS 2

    0 0

    0 0

    POLES 2

    -41.47 183.88

    -41.47 -183.88

    CONSTANT 1



    My concern is that I am converting to particle displacement twice in the
    process, firstly by integrated and then by removing the instrument
    response. It’s not clear from the help files how to specify the from format
    before the to format in addition to the polezero file.



    Thanks



    James







    Mr James Whittaker

    Research Assistant / Cymrawd Ymchwil

    Geoenvironmental Research Centre / Canolfan Ymchwil Geoamgylcheddol

    School of Engineering / Yr Ysgol Beirianneg

    Cardiff University / Prifysgol Caerdydd

    Queen's Buildings / Adeiladau'r Frenhines

    Newport Road / Heol Casnewydd

    Cardiff / Caerdydd

    CF24 3AA



    Email / Ebost: whittakerj4<at>cardiff.ac.uk




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