Thread: ppk rel help

Started: 2012-03-06 21:37:34
Last activity: 2012-03-07 22:30:56
Topics: SAC Help
Jeremy Pesicek
2012-03-06 21:37:34
sac helpers please help me

I have two questions:

1) why is the behavior of the commands 'p1 rel' and 'ppk rel' different? I can line up waveforms on a pick nicely using 'p1 rel', but when I use 'ppk rel', the same waves align on something different, on b I think. I found a previous post about this same issue back on July 5, 2006, but could not find a response to it. I want to make picks after aligning the waves on another pick.

2) I recently installed 101.5c and now my default xwindow size is much smaller. Is there a way to change the default xwindow size? I see that you can control the aspect ratio using vspace, but not the window size.

thanks,
Jeremy

  • Arthur Snoke
    2012-03-06 23:27:35
    Jeremy,

    I only have time for the second question as I do not use "rel" -- perhaps
    someone else can help you now on it.

    I think you can deal with window size, etc., using the window command.
    See http://www.iris.edu/software/sac/commands/window.html. A release
    ortwo ago we changed the windowing defaults to make things work bettr with
    the new ways to save plot files (saveimg). Let me know if you still have
    questions after looking at and trying the window command.

    Arthur

    On Tue, 6 Mar 2012, Jeremy Pesicek wrote:

    sac helpers please help me

    I have two questions:

    1) why is the behavior of the commands 'p1 rel' and 'ppk rel'
    different? I can line up waveforms on a pick nicely using 'p1 rel', but
    when I use 'ppk rel', the same waves align on something different, on b
    I think. I found a previous post about this same issue back on July 5,
    2006, but could not find a response to it. I want to make picks after
    aligning the waves on another pick.

    2) I recently installed 101.5c and now my default xwindow size is much
    smaller. Is there a way to change the default xwindow size? I see that
    you can control the aspect ratio using vspace, but not the window size.

  • George Helffrich
    2012-03-07 22:30:56
    Dear Jeremy -

    On 6 Mar 2012, at 19:37, Jeremy Pesicek wrote:

    sac helpers please help me

    I have two questions:

    1) why is the behavior of the commands 'p1 rel' and 'ppk rel' different? I can line up waveforms on a pick nicely using 'p1 rel', but when I use 'ppk rel', the same waves align on something different, on b I think. I found a previous post about this same issue back on July 5, 2006, but could not find a response to it. I want to make picks after aligning the waves on another pick.

    PPK parses 'relative' and 'absolute' but does not do anything different based on that option. For a pick window with multiple files, it always chooses as a time anchor the zero time in the first file and calculates a time window forward and backward from that which includes the data in all the rest of the files. You might design a pick strategy based on that behavior.

    George Helffrich
    george.helffrich<at>bris.ac.uk



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