Thread: Removing Instrument response

Started: 2019-10-06 12:16:07
Last activity: 2019-10-08 11:22:21
Topics: SAC Help
REHMAN .
2019-10-06 12:16:07
Hello,
I have download the SAC file from JWEED (IRIS), IDEP is not
available in the Header information. Then I removed the instrument response
using the response file by following the commands:

evalresp ${KSTNM} ${KCMPNM} ${YEAR} ${DAY} 0.01 50.0 1000 -u 'vel' -f resp
transfer from eval subtype afile pfile TO NONE FREQLIMITS 0.005 0.01 ${F3}
${F4}
rmean
taper
bp c 0.01 0.1 n 4 p 2
interpolate delta 1

Can anybody tell what is unit before and after instrument removal. I want
it should be in Velocity (Meters/second).
Below I am attaching SAC file before and after removal of instrument
response and also a response file.

  • Milton Plasencia
    2019-10-07 18:39:11
    Hi,

    Units before instrument removal is Digital Counts,
    When you applied the transfer command with “TO NONE” the output is displacement in meters,
    If you want velocity change to “TO VEL” an output will be m/s.

    HTH,

    Milton

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    On 7 Oct 2019, at 18:17, REHMAN . <rehman.geophy<at>gmail.com> wrote:

    Hello,
    I have download the SAC file from JWEED (IRIS), IDEP is not available in the Header information. Then I removed the instrument response using the response file by following the commands:

    evalresp ${KSTNM} ${KCMPNM} ${YEAR} ${DAY} 0.01 50.0 1000 -u 'vel' -f resp
    transfer from eval subtype afile pfile TO NONE FREQLIMITS 0.005 0.01 ${F3} ${F4}
    rmean
    taper
    bp c 0.01 0.1 n 4 p 2
    interpolate delta 1

    Can anybody tell what is unit before and after instrument removal. I want it should be in Velocity (Meters/second).
    Below I am attaching SAC file before and after removal of instrument response and also a response file.
    <RESP.G.AIS.00.BHZ><Raw-data.SAC><Response-removed.SAC>
    ----------------------
    SAC Help
    Topic home: http://ds.iris.edu/message-center/topic/sac-help/ | Unsubscribe: sac-help-unsubscribe<at>lists.ds.iris.edu

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  • George Helffrich
    2019-10-08 11:22:21
    Dear REHMAN -

    It is not clear what you’ve done from your description. Are these commands in SAC or are they processed by a shell somehow and given to SAC? So I have to guess about what you did, and the answer might not be as helpful as it could otherwise be.

    I seems that you used the shell to run some command called evalresp to extract an EVALRESP-style response into a file called “resp”. (You might look at the contents of “resp” to see what the output units are — EVALRESP-style files are generally wordy and readable by humans.) Then you somehow processed the other commands with the shell and gave them to SAC, setting frequency limit values for $(F3) and $(F4). Then SAC did a TRANSFER command and used the EVALRESP information in the file “afile” to change the data in the SAC file called “pfile” to some physical unit.

    “afile” should be the same file as “resp” for this to make sense. I assume “pfile” contains some SAC data.

    If this is indeed what you did, and the evalresp command produces a response file whose output units are velocity (like I think -u ‘vel’ means), then the SAC trace should have the physical units of velocity.

    On 8 Oct 2019, at 01:17, REHMAN . <rehman.geophy<at>gmail.com> wrote:

    Hello,
    I have download the SAC file from JWEED (IRIS), IDEP is not available in the Header information. Then I removed the instrument response using the response file by following the commands:

    evalresp ${KSTNM} ${KCMPNM} ${YEAR} ${DAY} 0.01 50.0 1000 -u 'vel' -f resp
    transfer from eval subtype afile pfile TO NONE FREQLIMITS 0.005 0.01 ${F3} ${F4}
    rmean
    taper
    bp c 0.01 0.1 n 4 p 2
    interpolate delta 1

    Can anybody tell what is unit before and after instrument removal. I want it should be in Velocity (Meters/second).
    Below I am attaching SAC file before and after removal of instrument response and also a response file.
    <RESP.G.AIS.00.BHZ><Raw-data.SAC><Response-removed.SAC>
    ----------------------
    SAC Help
    Topic home: http://ds.iris.edu/message-center/topic/sac-help/ | Unsubscribe: sac-help-unsubscribe<at>lists.ds.iris.edu

    Sent from the IRIS Message Center (http://ds.iris.edu/message-center/)
    Update subscription preferences at http://ds.iris.edu/account/profile/



    George Helffrich
    george<at>elsi.jp


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