Thread: spectrogram questions

Started: 2018-05-10 21:17:22
Last activity: 2018-05-18 07:28:50
Topics: SAC Help
Mar Tapia
2018-05-10 21:17:22
Hi,

I have some questions related to spectrogram function in sac:

1. How can I save the results from spectrogram function in order to plot
with other softwares?

2. And is it possible to control the colorbar values in some way?

3. I don't understand why the spectogram plot using PSD method is so
different from the spectrogram function in matlab using same window length.
Is there any smooth or ponderation in the final results in order to show
better singularities or important zones?

Thanks in advance,

Mar



--
-----------------------------------------------------------
Mar Tapia

mar.tapia<at>gmail.com
------------------------------------------------------------

  • George Helffrich
    2018-05-17 20:28:45
    Dear All -

    1) The SPECTROGRAM results may be obtained from SAC by using the XYZ option. This leaves the result in an XYZ file in memory that may be written out and read by an auxiliary program for subsequent processing (or plotting). The SAC XYZ file format is documented in online sources and in Chapter 2 of the SAC book. The online resources associated with the book contain example code that writes and, I think, reads SAC XYZ files.

    2) You can use the COLOR command to define an alternate color palette that will also be used in the color bar. See the COLOR RASTER command in Chapter 10 of the SAC book for an example. Different versions of SAC might not have the same set of built-in color maps available, however.

    With some effort, you can design and plot your own color bar by making a composite plot and plotting the color bar as a separate XYZ file. See Chapter 7 of the SAC book for an introduction to composite plots.

    3) Not being a MATLAB user I can’t comment on differences in the appearance of any spectrograms that it calculates compared to SAC.

    On 10 May 2018, at 21:18, Mar Tapia <mar.tapia<at>gmail.com> wrote:

    Hi,

    I have some questions related to spectrogram function in sac:

    1. How can I save the results from spectrogram function in order to plot with other softwares?

    2. And is it possible to control the colorbar values in some way?

    3. I don't understand why the spectogram plot using PSD method is so different from the spectrogram function in matlab using same window length. Is there any smooth or ponderation in the final results in order to show better singularities or important zones?

    Thanks in advance,

    Mar



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    -----------------------------------------------------------
    Mar Tapia

    mar.tapia<at>gmail.com
    ------------------------------------------------------------

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    George Helffrich
    george<at>elsi.jp


    • Aaron
      2018-05-17 15:49:49
      Dear George:

      I was just looking at the answer given to Mar Tapia and wanted to try the
      command. However, I got an error when I used XYZ option. This is SAC
      version 101.6.

      SEISMIC ANALYSIS CODE [06/12/2013 (Version 101.6)]
      Copyright 1995 Regents of the University of California

      SAC> FUNCGEN SEISMOGRAM
      SAC> SPECTROGRAM XYZ
      ERROR interpreting command: SPECTROGRAM XYZ
      ILLEGAL OPTION: ^


      Aaron

      On Wed, May 16, 2018 at 10:29 PM, George Helffrich <george<at>elsi.jp> wrote:

      Dear All -

      1) The SPECTROGRAM results may be obtained from SAC by using the XYZ
      option. This leaves the result in an XYZ file in memory that may be
      written out and read by an auxiliary program for subsequent processing (or
      plotting). The SAC XYZ file format is documented in online sources and in
      Chapter 2 of the SAC book. The online resources associated with the book
      contain example code that writes and, I think, reads SAC XYZ files.

      2) You can use the COLOR command to define an alternate color palette that
      will also be used in the color bar. See the COLOR RASTER command in
      Chapter 10 of the SAC book for an example. Different versions of SAC might
      not have the same set of built-in color maps available, however.

      With some effort, you can design and plot your own color bar by making a
      composite plot and plotting the color bar as a separate XYZ file. See
      Chapter 7 of the SAC book for an introduction to composite plots.

      3) Not being a MATLAB user I can’t comment on differences in the
      appearance of any spectrograms that it calculates compared to SAC.

      On 10 May 2018, at 21:18, Mar Tapia <mar.tapia<at>gmail.com> wrote:

      Hi,

      I have some questions related to spectrogram function in sac:

      1. How can I save the results from spectrogram function in order to plot
      with other softwares?

      2. And is it possible to control the colorbar values in some way?

      3. I don't understand why the spectogram plot using PSD method is so
      different from the spectrogram function in matlab using same window length.
      Is there any smooth or ponderation in the final results in order to show
      better singularities or important zones?

      Thanks in advance,

      Mar



      --
      -----------------------------------------------------------
      Mar Tapia

      mar.tapia<at>gmail.com
      ------------------------------------------------------------

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      George Helffrich
      george<at>elsi.jp



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      --
      Aarón Moya
      Laboratorio de Ingeniería Sísmica
      Instituto de Investigaciones en Ingeniería
      Universidad de Costa Rica
      San José, COSTA RICA
      Tel: 2253-7331 Fax: 2224-2619
      http://www.lis.ucr.ac.cr

      • George Helffrich
        2018-05-18 07:28:50
        Dear All -

        It appears that the XYZ spectrogram option disappeared at some point from the SAC version distributed by IRIS, which thwarts quantitative comparison with alternative spectrogram calculation methods. Hence, I must add the disclaimer that the comments apply to the SAC version described in the SAC book. Sorry for any confusion.

        On 17 May 2018, at 23:50, Aaron <aaronmoya<at>gmail.com> wrote:

        Dear George:

        I was just looking at the answer given to Mar Tapia and wanted to try the command. However, I got an error when I used XYZ option. This is SAC version 101.6.

        SEISMIC ANALYSIS CODE [06/12/2013 (Version 101.6)]
        Copyright 1995 Regents of the University of California

        SAC> FUNCGEN SEISMOGRAM
        SAC> SPECTROGRAM XYZ
        ERROR interpreting command: SPECTROGRAM XYZ
        ILLEGAL OPTION: ^


        Aaron

        On Wed, May 16, 2018 at 10:29 PM, George Helffrich <george<at>elsi.jp> wrote:
        Dear All -

        1) The SPECTROGRAM results may be obtained from SAC by using the XYZ option. This leaves the result in an XYZ file in memory that may be written out and read by an auxiliary program for subsequent processing (or plotting). The SAC XYZ file format is documented in online sources and in Chapter 2 of the SAC book. The online resources associated with the book contain example code that writes and, I think, reads SAC XYZ files.

        2) You can use the COLOR command to define an alternate color palette that will also be used in the color bar. See the COLOR RASTER command in Chapter 10 of the SAC book for an example. Different versions of SAC might not have the same set of built-in color maps available, however.

        With some effort, you can design and plot your own color bar by making a composite plot and plotting the color bar as a separate XYZ file. See Chapter 7 of the SAC book for an introduction to composite plots.

        3) Not being a MATLAB user I can’t comment on differences in the appearance of any spectrograms that it calculates compared to SAC.

        On 10 May 2018, at 21:18, Mar Tapia <mar.tapia<at>gmail.com> wrote:

        Hi,

        I have some questions related to spectrogram function in sac:

        1. How can I save the results from spectrogram function in order to plot with other softwares?

        2. And is it possible to control the colorbar values in some way?

        3. I don't understand why the spectogram plot using PSD method is so different from the spectrogram function in matlab using same window length. Is there any smooth or ponderation in the final results in order to show better singularities or important zones?

        Thanks in advance,

        Mar



        --
        -----------------------------------------------------------
        Mar Tapia

        mar.tapia<at>gmail.com
        ------------------------------------------------------------

        ----------------------
        SAC Help
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        George Helffrich
        george<at>elsi.jp



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        --
        Aarón Moya
        Laboratorio de Ingeniería Sísmica
        Instituto de Investigaciones en Ingeniería
        Universidad de Costa Rica
        San José, COSTA RICA
        Tel: 2253-7331 Fax: 2224-2619
        http://www.lis.ucr.ac.cr

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        George Helffrich
        george<at>elsi.jp


        • Wen-Tzong Liang
          2018-05-18 06:51:20
          We can still output the spectrogram result with the "write sac output.sac"
          command as a 3D XYZ file. After reading this xyz file in SAC, the "contour"
          and "image" commands can be applied accordingly.

          Wen-Tzong Liang




          George Helffrich <george<at>elsi.jp> 於 2018年5月17日 週四 下午11:29 寫道:

          Dear All -

          It appears that the XYZ spectrogram option disappeared at some point from
          the SAC version distributed by IRIS, which thwarts quantitative comparison
          with alternative spectrogram calculation methods. Hence, I must add the
          disclaimer that the comments apply to the SAC version described in the SAC
          book. Sorry for any confusion.

          On 17 May 2018, at 23:50, Aaron <aaronmoya<at>gmail.com> wrote:

          Dear George:

          I was just looking at the answer given to Mar Tapia and wanted to try the
          command. However, I got an error when I used XYZ option. This is SAC
          version 101.6.

          SEISMIC ANALYSIS CODE [06/12/2013 (Version 101.6)]
          Copyright 1995 Regents of the University of California

          SAC> FUNCGEN SEISMOGRAM
          SAC> SPECTROGRAM XYZ
          ERROR interpreting command: SPECTROGRAM XYZ
          ILLEGAL OPTION: ^


          Aaron

          On Wed, May 16, 2018 at 10:29 PM, George Helffrich <george<at>elsi.jp> wrote:

          Dear All -

          1) The SPECTROGRAM results may be obtained from SAC by using the XYZ
          option. This leaves the result in an XYZ file in memory that may be
          written out and read by an auxiliary program for subsequent processing (or
          plotting). The SAC XYZ file format is documented in online sources and in
          Chapter 2 of the SAC book. The online resources associated with the book
          contain example code that writes and, I think, reads SAC XYZ files.

          2) You can use the COLOR command to define an alternate color palette
          that will also be used in the color bar. See the COLOR RASTER command in
          Chapter 10 of the SAC book for an example. Different versions of SAC might
          not have the same set of built-in color maps available, however.

          With some effort, you can design and plot your own color bar by making a
          composite plot and plotting the color bar as a separate XYZ file. See
          Chapter 7 of the SAC book for an introduction to composite plots.

          3) Not being a MATLAB user I can’t comment on differences in the
          appearance of any spectrograms that it calculates compared to SAC.

          On 10 May 2018, at 21:18, Mar Tapia <mar.tapia<at>gmail.com> wrote:

          Hi,

          I have some questions related to spectrogram function in sac:

          1. How can I save the results from spectrogram function in order to plot
          with other softwares?

          2. And is it possible to control the colorbar values in some way?

          3. I don't understand why the spectogram plot using PSD method is so
          different from the spectrogram function in matlab using same window length.
          Is there any smooth or ponderation in the final results in order to show
          better singularities or important zones?

          Thanks in advance,

          Mar



          --
          -----------------------------------------------------------
          Mar Tapia

          mar.tapia<at>gmail.com
          ------------------------------------------------------------

          ----------------------
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          George Helffrich
          george<at>elsi.jp



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          --
          Aarón Moya
          Laboratorio de Ingeniería Sísmica
          Instituto de Investigaciones en Ingeniería
          Universidad de Costa Rica
          San José, COSTA RICA
          Tel: 2253-7331 Fax: 2224-2619
          http://www.lis.ucr.ac.cr

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          George Helffrich
          george<at>elsi.jp


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          • Mar Tapia
            2018-05-18 03:34:55
            Thanks for your answers!!!!

            El jue., 17 may. 2018 17:52, Wen-Tzong Liang <wtl<at>earth.sinica.edu.tw>
            escribió:

            We can still output the spectrogram result with the "write sac output.sac"
            command as a 3D XYZ file. After reading this xyz file in SAC, the "contour"
            and "image" commands can be applied accordingly.

            Wen-Tzong Liang




            George Helffrich <george<at>elsi.jp> 於 2018年5月17日 週四 下午11:29 寫道:

            Dear All -

            It appears that the XYZ spectrogram option disappeared at some point from
            the SAC version distributed by IRIS, which thwarts quantitative comparison
            with alternative spectrogram calculation methods. Hence, I must add the
            disclaimer that the comments apply to the SAC version described in the SAC
            book. Sorry for any confusion.

            On 17 May 2018, at 23:50, Aaron <aaronmoya<at>gmail.com> wrote:

            Dear George:

            I was just looking at the answer given to Mar Tapia and wanted to try the
            command. However, I got an error when I used XYZ option. This is SAC
            version 101.6.

            SEISMIC ANALYSIS CODE [06/12/2013 (Version 101.6)]
            Copyright 1995 Regents of the University of California

            SAC> FUNCGEN SEISMOGRAM
            SAC> SPECTROGRAM XYZ
            ERROR interpreting command: SPECTROGRAM XYZ
            ILLEGAL OPTION: ^


            Aaron

            On Wed, May 16, 2018 at 10:29 PM, George Helffrich <george<at>elsi.jp>
            wrote:

            Dear All -

            1) The SPECTROGRAM results may be obtained from SAC by using the XYZ
            option. This leaves the result in an XYZ file in memory that may be
            written out and read by an auxiliary program for subsequent processing (or
            plotting). The SAC XYZ file format is documented in online sources and in
            Chapter 2 of the SAC book. The online resources associated with the book
            contain example code that writes and, I think, reads SAC XYZ files.

            2) You can use the COLOR command to define an alternate color palette
            that will also be used in the color bar. See the COLOR RASTER command in
            Chapter 10 of the SAC book for an example. Different versions of SAC might
            not have the same set of built-in color maps available, however.

            With some effort, you can design and plot your own color bar by making a
            composite plot and plotting the color bar as a separate XYZ file. See
            Chapter 7 of the SAC book for an introduction to composite plots.

            3) Not being a MATLAB user I can’t comment on differences in the
            appearance of any spectrograms that it calculates compared to SAC.

            On 10 May 2018, at 21:18, Mar Tapia <mar.tapia<at>gmail.com> wrote:

            Hi,

            I have some questions related to spectrogram function in sac:

            1. How can I save the results from spectrogram function in order to plot
            with other softwares?

            2. And is it possible to control the colorbar values in some way?

            3. I don't understand why the spectogram plot using PSD method is so
            different from the spectrogram function in matlab using same window length.
            Is there any smooth or ponderation in the final results in order to show
            better singularities or important zones?

            Thanks in advance,

            Mar



            --
            -----------------------------------------------------------
            Mar Tapia

            mar.tapia<at>gmail.com
            ------------------------------------------------------------

            ----------------------
            SAC Help
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            George Helffrich
            george<at>elsi.jp



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            --
            Aarón Moya
            Laboratorio de Ingeniería Sísmica
            Instituto de Investigaciones en Ingeniería
            Universidad de Costa Rica
            San José, COSTA RICA
            Tel: 2253-7331 Fax: 2224-2619
            http://www.lis.ucr.ac.cr

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            George Helffrich
            george<at>elsi.jp


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