EdgeTech X-Star sub-bottom profiler example.

A 2001 example plot.
The processing was done in three steps:
1)  Read the data tapes onto disk.
2)  Convert the Edgetech format to SEGY and filter (script).
3)  Pick the water bottom, mute, apply gain, and plot (script).

EdgeTech's SEG-Y is slightly different from SIOSEIS's, but
SIOSEIS process HEADER and GAINS can rectify the differences.
An analysis of the differences is included here.

A sioseis script that reads and converts ALL the xstar files 
in a directory and writes each as a SEG-Y/IEEE tape file.


    The EdgeTech X-Star is a towed fish whose depth varies
depending on the length of leader out, the boat's speed, etc.
When the fish goes up or down, the time of the seismic returns
will also vary.  Sometimes this variation causes interpretation
errors; the data need to be corrected to a constant datum.
    The following two schemes do datum corrections so that the
data appear to be shot from sea level.  Each ping is corrected
separately so that the fish depth variations are also removed.
One scheme shifts the data so that the water bottom time on each
ping is the same as the period of the water bottom multiple.
The second scheme utilizes the water depth information collected
from a separate XYZ file that was derived from a SeaBeam cruise.
    The data were stored on the IGPP mass store in their
original XSTAR format and were converted to SEGY using process
XSTAR while reading to the local disk.
    In the first method, the water bottom multiple period is
determined by picking the autocorrelation using script.  The
standard output was redirected to a file which was subsequently used
in a script which picks the water bottom, subtracts it from
the multiple period and shifts the ping.  The data were then plotted
with gray scale using script.
    The second datum correction method was needed because the water
depth was to deep for the multiple to be recorded.  The uncorrected
section is quite misleading when compared to the datum corrected
section without a shift mix, or
section with a 20 trace shift mix
These sections were created in two steps (scripts).



Some 1999 work follows

plot of just the traces 1s was generated by this script.

plot of just the traces 2s.

plot of just the traces 1s was generated by this script.

Go to the list of seismic processes.      Go to SIOSEIS introduction.