                          PLOTSEGY V2.0
                     Changes to the Program
                                

     PLOTSEGY V2.0 incorporates 4 major changes in function:

  1) The ability to change the sample rate used or replace it if
     not found in the SEG-Y binary header.
  2) The ability to scale the display of the data as either
     "trace normalized" or against a "relative amplitude" either
     calculated or entered by the user.
  3) A trace increment parameter.
  4) The ability to display 3 different trace header values.
   
These last two changes allow PLOTSEGY to display unstacked SEG-Y
data and label it appropriately.

     Shown in figures 1 - 7 are the user-interface changes seen
in PLOTSEGY V2.0.


                           SAMPLE RATE

     After PLOTSEGY has opened the indicated input file and read
the binary trace header information, the sample rate found in the
binary header is displayed and the user has an opprotunity to
change it if desired.  The default value found in the binary
header is displayed in square brackets ([sample rate]) and may be
accepted by pressing <ENTER>.  The user may enter a new value at
the prompt, or "quit" or "exit".  The sample rate accepted will
be used in all subsequent calculations.


                   SCALING - TRACE NORMALIZED

     Trace Normalized scaling will compute the average non-zero
absolute sample value per trace and use that value to represent
1/2 a trace width when plotting that trace's samples.  Each
sample will be displayed relative to that average value for that
trace.















                                                              1

                  SCALING - RELATIVE AMPLITUDE

     Relative Amplitude scaling will take a user-defined set of
traces from within the input file indicated and use the sample
values of that set of data traces to compute the average non-zero
absolute sample value representing 1/2 a trace width when
plotting all samples within the data set.


                         TRACE INCREMENT

     The Trace Increment parameter allows the user to increment
the trace counter through the data.  For unstacked data, this
allows the user to display individual traces from each ensemble.
For example, Lake Baikal line 6 SEG-Y demultiplexed data has
ensembles composed of 101 traces: 5 auxilary channels (traces 1 -
5) and 96 data channels (traces 6 - 101).  Ensemble trace 6 is
the 1st data trace per ensemble and represents the far trace.
Ensemble trace 101 is the 96th data trace per ensemble and
represents the near data trace.  PLOTSEGY uses a counter locate
ALL the physical traces in the file, where the 1st trace in the
file is physical trace number 1.  PLOTSEGY V2.0 will display ALL
traces per ensemble, including the auxilliary traces, so they
must be included in calculating a starting trace value.  The
PLOTSEGY V2.0 parameter 1st_trace_number is the number of the 1st
physical trace in the file to display.  If the data set is
composed of 10 shot ensembles, the near trace for those 10 shots
may be displayed by setting the PLOTSEGY V2.0 parameter
1st_trace_number to the SEG-Y file physical trace 101 and the
parameter trace_increment to 101.  This will produce a display
using physical traces 101, 202, 303, 404, 505, 606, 707, 808, 909
and 1010, which represent ensemble trace 101 for shots 1 through
10.  A far trace display is possible by setting PLOTSEGY V2.0
parameter 1st_trace_number to physical trace 6 and the parameter
trace_increment to 101.  This will produce a display using
physical traces 6, 107, 208, 309, 410, 511, 612, 713, 814, and
915, which represent ensemble trace 6 for shots 1 through 10.

     For stacked data, this allows the user to simulate the
display more data per screen ("panel") then is physically
possible.  If the display monitor has VGA resolution, it is
capable of displaying 550 traces per panel.  If the SEG-Y data
being displayed has 1100 traces in the data set, the "entire"
line may be displayed by setting the PLOTSEGY V2.0 parameter
traces_per_panel to 550 and the PLOTSEGY V2.0 parameter
trace_increment to 2.  This will decimate the data, displaying
every other trace and simulates displaying 1100 traces per panel.


                      TRACE HEADER DISPLAYS

     PLOTSEGY V2.0 annotates traces with the physical trace
number within the file, labelled "File Trace", and one of 3 trace
header values.  The user may select header value CDP, ensemble

                                                              2

trace number, or the original field record number (FFID) of that
trace.





















































                                                              3

----------------------------------------
       SEGY INPUT FILE PARAMETERS
----------------------------------------

CURRENT WORKING DIRECTORY: D:\CPGMS\SEGY\P5

CURRENT FILE PATH: D:\CPGMS\SEGY\P5
enter new path, "exit", "-" to use the current working directory
or press ENTER to use current file path: ..\DATA


CURRENT FILE NAME:
enter new name, "exit" or press ENTER to use current: 624-79.SGY


624-79.SGY currently has a sample rate of [   4.000] msec.
Enter a new sample rate if desired.  Press <CR> to accept current
value.
sample rate [   4.000]:

FIGURE 1: PLOTSEGY V2.0 SEG-Y Input File Parameters Screen.


































                                                              4

-----------------------------
DISPLAY TRACE SCALING METHODS
-----------------------------

NORMALIZED:         PLOTSEGY will average the amplitudes within
                    the current trace being plotted and uses that
                    amplitude to represent 1/2 the trace width
                    for the display of that trace.

RELATIVE AMPLITUDE: The user selects a starting trace and the
                    number of traces to use.  PLOYSEGY will
                    average the amplitudes found for all samples
                    within that range of traces and uses that
                    amplitude to represent 1/2 a trace width for
                    the display of all traces in the data set.

Trace scaling: (1) normalized  (2) relative amplitude
scaling [1]: 2

FIGURE 2: PLOTSEGY V2.0 Scaling Methods Screen.



Press any key to accept the current relative amplitude to use for
plotting.  Enter a new relative amplitude value or press "C" to
compute a new one.
Current relative amplitude value [   0.000]: C

FIGURE 3: User has selected to scale the data using a relative
amplitude to be computed ("C").




Traces in file 624-79.sgy: [493]
The relative amplitude is computed by averaging the sample values
over a range of traces given by a starting trace number and the
number of traces to use.

starting trace number: 200
number of traces to use: 10

FIGURE 4: User has requested the relative amplitude be computed
from the average of the sample values found in traces 200 - 209.




trace [200] average amplitude [134455664.000]
trace [201] average amplitude [134324672.000]
trace [202] average amplitude [134405600.000]
trace [203] average amplitude [133956936.000]
trace [204] average amplitude [133936984.000]
trace [205] average amplitude [134326336.000]

                                                              5

trace [206] average amplitude [134122296.000]
trace [207] average amplitude [134137880.000]
trace [208] average amplitude [134346800.000]
trace [209] average amplitude [134024192.000]

FIGURE 5: PLOTSEGY V2.0 display of calculating the average
relative amplitude to be used.




----------------------------------------
       INPUT FILE CHARACTERISTICS
----------------------------------------

            FILE: 624-79.sgy
      sample rate:    4.000 msec
number of samples:     1500
     maximum time:     6000 msec
  bytes per trace:     6240
    bytes in file:  3079920
   traces in file:      493
         scaling: RELATIVE AMPLITUDE
   scaling factor: 134203736.000

Press any key to continue...

FIGURE 6: Input file characteristics displayed by PLOTSEGY V2.0
after computing a new relative amplitude.


























                                                              6

----------------------------------------
          TRACE PLOTTING TYPES
----------------------------------------
TRACE TYPES: (1) wiggle  (2) variable area  (3) both
trace type [3]:

----------------------------------------
           PLOT DISPLAY TIMES
----------------------------------------
minimum time [0]:

maximum time [6000]: 1000

timing lines [1000]: 100

<NEW PAGE>

----------------------------------------
         TRACE PARAMETERS
----------------------------------------
trace gain [1.000]: 1.5

trace clipping [3]: 1

1st trace number [1]:

Maximum horizontal resolution is 550 traces per panel.
traces per panel [125]:

trace annotation frequency [10]:

trace increment [1]:

Header value to display:
(1) CDP Number   (2) Ensemble Trace Number   (3) Field File
Number
header value [1]:

Figure 7: PLOTSEGY V2.0 Trace Information entry screen.
















                                                              7
