Thread: SAC Read SEGY

Started: 2014-05-06 17:27:27
Last activity: 2020-01-09 12:10:35
Topics: SAC Help
Baumgardt.Doug
2014-05-06 17:27:27
I have downloaded data in PASSCAL SEGY format, one file per channel. However, when I try to read in one of the files with the command 'read SEGY {filename}, , I receive an error message "ERROR 1340: data points outside allowed range contained in file {file name}". What does this mean and how do I read this data in?

Douglas R. Baumgardt


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  • Rob Casey
    2014-05-06 15:38:51

    Hi Doug-

    I think you can find the answer here: https://www.passcal.nmt.edu/content/seg-y-what-it-is

    The original segy format doesn't allow more than 32k samples in a trace. The PASSCAL format allows this to be longer. Not sure what the remedy is for this for SAC users, but PASSCAL had a version of segy2sac that could read PASSCAL SEGY and convert it to SAC. You might find it somewhere here: http://www.passcal.nmt.edu/content/software-resources

    -Rob


    On May 6, 2014, at 7:27 AM, Baumgardt.Doug wrote:

    I have downloaded data in PASSCAL SEGY format, one file per channel. However, when I try to read in one of the files with the command ‘read SEGY {filename}, , I receive an error message “ERROR 1340: data points outside allowed range contained in file {file name}”. What does this mean and how do I read this data in?

    Douglas R. Baumgardt


    The information contained in this email message is intended only for the use of the individual(s) to whom it is addressed and may contain information that is privileged and sensitive. If you are not the intended recipient, or otherwise have received this communication in error, please notify the sender immediately by email at the above referenced address and note that any further dissemination, distribution or copying of this communication is strictly prohibited.

    The U.S. Export Control Laws regulate the export and re-export of technology originating in the United States. This includes the electronic transmission of information and software to foreign countries and to certain foreign nationals. Recipient agrees to abide by these laws and their regulations -- including the U.S. Department of Commerce Export Administration Regulations and the U.S. Department of State International Traffic in Arms Regulations -- and not to transfer, by electronic transmission or otherwise, any content derived from this email to either a foreign national or a foreign destination in violation of such laws.
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    • Brian Savage
      2014-05-06 19:31:02
      Dear Doug,

      We can modify SAC so it conforms to the PASSCAL format, if need be.

      SAC currently has a check for the number of points in the file, and it looks like what Rob says is correct, sort of.
      There is the functionality to read in more than 32767 data points.

      Try dumping out the number of samples with
      %od -t dS -j 114 -N 2 filename.segy
      0000162 32767
      0000164

      If the second number on the first line is 32767, then the number of points *might* be found at a later position. If it is not 32767, then it is probably the number of points, unless it is negative.

      To get the value at a later position, try
      % od -t d -j 228 -N 4 filename.segy
      0000344 1000000
      0000350

      Again you want the second number on the first line.

      I created this SEGY file in SAC using

      SAC> SAC> fg random npts 1000000
      SAC> write segy filename.segy

      Brian

      On May 6, 2014, at 11:38 AM, Robert Casey wrote:


      Hi Doug-

      I think you can find the answer here: https://www.passcal.nmt.edu/content/seg-y-what-it-is

      The original segy format doesn't allow more than 32k samples in a trace. The PASSCAL format allows this to be longer. Not sure what the remedy is for this for SAC users, but PASSCAL had a version of segy2sac that could read PASSCAL SEGY and convert it to SAC. You might find it somewhere here: http://www.passcal.nmt.edu/content/software-resources

      -Rob


      On May 6, 2014, at 7:27 AM, Baumgardt.Doug wrote:

      I have downloaded data in PASSCAL SEGY format, one file per channel. However, when I try to read in one of the files with the command ‘read SEGY {filename}, , I receive an error message “ERROR 1340: data points outside allowed range contained in file {file name}”. What does this mean and how do I read this data in?

      Douglas R. Baumgardt


      The information contained in this email message is intended only for the use of the individual(s) to whom it is addressed and may contain information that is privileged and sensitive. If you are not the intended recipient, or otherwise have received this communication in error, please notify the sender immediately by email at the above referenced address and note that any further dissemination, distribution or copying of this communication is strictly prohibited.

      The U.S. Export Control Laws regulate the export and re-export of technology originating in the United States. This includes the electronic transmission of information and software to foreign countries and to certain foreign nationals. Recipient agrees to abide by these laws and their regulations -- including the U.S. Department of Commerce Export Administration Regulations and the U.S. Department of State International Traffic in Arms Regulations -- and not to transfer, by electronic transmission or otherwise, any content derived from this email to either a foreign national or a foreign destination in violation of such laws.
      _______________________________________________
      sac-help mailing list
      sac-help<at>iris.washington.edu
      http://www.iris.washington.edu/mailman/listinfo/sac-help

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


    • wenai.oc@gmail.com
      2018-03-22 13:31:09
      Hi Rob

      How to transform the original segy format to PASSCAL format?

      Thank you.

      Wenai Hou
    • Tong Bai
      2020-01-09 06:52:54
      Hi Rob,

      Could you please be more specific about which software have the segy2sac function? The link has several packages and it seems none have straightforward correlations with segy2sac. Not sure something changed after so many years...

      Thank you very much for your help!

      Best regards,
      Tong
      • Rob Casey
        2020-01-09 10:51:14

        Hi Tong-

        segy2sac has been around in some form for a very long time, and since I don't use the utility in my day to day work, I can't personally recommend which one you should use. Do you work in python at all? If so, it looks like ObsPy has support for SEGY import and SAC writing. Someone on github put together a python script that drives ObsPy to act as a segy2sac utility.

        https://github.com/mprocha/scripts/blob/master/segy2sac.py

        If you need an original binary build for a specific platform, I can try to do some more digging, but from what I can see, it's always bundled with a collection of converters. It's not a tool we maintain at IRIS DMC. The best bet would be to see if you can get ObsPy to work for you, since that is actively maintained.

        -Rob


        On Jan 9, 2020, at 10:30 AM, Tong Bai <tbai4<at>wisc.edu> wrote:

        Hi Rob,

        Could you please be more specific about which software have the segy2sac function? The link has several packages and it seems none have straightforward correlations with segy2sac. Not sure something changed after so many years...

        Thank you very much for your help!

        Best regards,
        Tong

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