Thread: Hellp, This is Lee. I have a question about SAC file format structure

Started: 2010-12-23 20:02:11
Last activity: 2010-12-23 20:02:11
Topics: SAC Help
 Hello, this is Lee.

 I want to build my own SAC read-write program. Like a Guralp guys did.

 But I can't find information about detailed SAC file format structure.

 I want more detailed structure information. Like SEED manual.

 Do you have a SAC file format structure manual? Or something detailed
description?

 If not, can you tell me how guralp guys did it?(I mean, SCREAM!
program..It can export data in SAC format.)


 Thank you.

 Lee.


  • Here are a couple links describing the format:

    http://www.iris.edu/manuals/sac/SAC_Manuals/FileFormatPt1.html
    http://www.iris.edu/KB/questions/13/SAC+file+format

    There are library routines in the sac libraries included with the sac
    download. Your best bet is to link against the library and call rsac1 or
    wsac1.

    Don't want to use the library? Read on...
    Its basically a block of metadata (158 32-bit words) and then just a block
    of floating point values. The typical method you could employ is to read the
    header block, check against bit-swapping, and then read the data-only part.
    You would then return the data array and header structure to your main
    routine.

    I've been working on a wiki for seismology:
    http://seismowiki2.pbworks.com/w/page/28169580/Data-Processing
    on this site I've posted a tutorial for basic matlab functions which mimic
    sac (better just to compile SAC in a method to play nicely with matlab, but
    this helps illustrate some concepts).
    http://seismowiki2.pbworks.com/f/porritt_broadband_processing_matlab.zip
    included in the 'functions' folder of this zip file are ones called
    readsac.m, load_sac.m, and write_sac.m which I've altered slightly from the
    original codes to account for bit swapping. If you're familiar with Matlab,
    you could mimic the general methods of those codes for your language of
    choice.

    Cheers,
    Rob Porritt
    Berkeley Seismological Laboratory
    UC Berkeley


    On Wed, Dec 22, 2010 at 7:02 PM, Donghoon Lee <physics6<at>gmail.com> wrote:

    Hello, this is Lee.

    I want to build my own SAC read-write program. Like a Guralp guys did.

    But I can't find information about detailed SAC file format structure.

    I want more detailed structure information. Like SEED manual.

    Do you have a SAC file format structure manual? Or something detailed
    description?

    If not, can you tell me how guralp guys did it?(I mean, SCREAM!
    program..It can export data in SAC format.)


    Thank you.

    Lee.

    _______________________________________________
    sac-help mailing list
    sac-help<at>iris.washington.edu
    http://www.iris.washington.edu/mailman/listinfo/sac-help




    --
    Rob Porritt, GG
    UC Berkeley Earth and Planetary Sciences PhD Candidate
    Berkeley Seismological Laboratory
    http://seismo.berkeley.edu/~rob/

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