Quick notes on two files Mark Legg sent via cd.


Step 1 is to do an lsd.
>lsd smcs05a.sgy  | more
      SHOT   TR       RP    TR ID  RANGE DELAY NSAMPS    SI   YR DAY HR MIN SEC
         2     0       0     1  1      0     0   8192     0    3   9 13   9  15
         2     1       0     1  1      0     0   8192     0    3   9 13   9  15
         2     2       0     1  1      0     0   8192     0    3   9 13   9  15
         2     3       0     1  1      0     0   8192     0    3   9 13   9  15
         2     4       0     1  1      0     0   8192     0    3   9 13   9  15
.
.
         2    25       0     1  1      0     0   8192     0    3   9 13   9  15
         2    26       0     1  1      0     0   8192     0    3   9 13   9  15
         2    27       0     1  1      0     0   8192     0    3   9 13   9  15
         3     0       0     1  1      0     0   8192     0    3   9 13   9  21
         3     1       0     1  1      0     0   8192     0    3   9 13   9  21


The data are in an "unusual" version of SEG-Y.  An old version of VISTA
created the "SEG-Y" files and have several idiosynracies.

1)  The sample interval is not in the trace header.  It only
    appears in the SEG-Y binary header.
    Solution: Use Sioseis process diskin parameter   si .0005
2)  The trace numbering starts with 0 rather than 1.
    Solution: Use Sioseis process header to add 1 to the trace number.
3)  The trace number within the cmp ensemble (SEGY word 7) is
    set to 1, so sioseis thinks the data is cmp sorted.
    Solution: Use Sioseis process header to set word 7 to 0.
4)  The trace numbering is backwards from convention.  Normally,
    trace 1 is the furthest from the ship.  Not a problem, but ...
    Solution:  Just define the geometry as is in process geom.
5)  Trace 20 is bad in line 3a and trace 6 is bad on line 5a.
    Solution: Use process tredit to detect the bad traces and kill them.
6)  Traces 1-24 are from the port (Barth) streamer, 25-28 are from the
    starboard (SIO) streamer.
    Solution:  Use ftr 0 ltr 23 to process the main streamer.
7)  The streamer has unusual group spacing.  Use geom:
    dfls 12.5 gxp 1 -11.63 ggx 3.125 dbrps 1.5625 smear 1.5625  end

Script to plot a shot.
Script to gather line 3a.
Script to qc plot a few rps.
    There are some bad/noisey traces.  The best trace killer was
to look for high amplitudes in the deep part of the every trace.
Script print some trace amplitudes.
Script to kill and plot the same rps.
Script to constant velocity stack line 5a.
Script to post stack process and plot.
Script and gray scale plot.