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Program Manipulation

Digitization

After starting the job (dgs &) main window is appeared. First of all it is necessary to click the "Etc" button, then enter PCX file name in the corresponding panel line and depress the button Apply. (One may also depress the "Return" key on the Keyboard instead of "Apply"). The file loading is a comparatively long process (10-30 s) so one would wait until the whole completion.

The order of User's actions may be arbitrary: (1) time scale binding, (2) human time setting, and (3) digitizing. Nevertheless to minimize the user's efforts, we recommend, in general, next sequence of actions:


Once when the quality of the package of the paper datagrams is became to be known a user should tune the selection parameters and then set them every time after the program starts.

At the beginning of datagram processing a user should check if the trend is present on datagram; if yes - perform rotation of image; set time-unit, human time for the seismogram and perform time scale binding for the image; set the options and parameters for dispiking. To select the optimal length for median window one should take into account: the more the window length is set the more smoothing effect would appear onto the curves. set the options and parameters for filtering. To evaluate the appropriate frequency band one should switch the program to the "Msr" mode and perform measurement of the dominant period of the oscillation (in pixels). set two boundaries; perform "Enhancing" - the global preliminary cleaning of the vertical grid lines, which prevent to digitizing; save datagram in PCX-file for a case.

For every interested trace: perform the delicate erasing of the dirt spots or other unnecessary lines, which prevent to digitizing (if needed); select/unselect axis and/or select/unselect segments; perform digitization, repeated selection and unselection of segments and recursive digitization; perform manual trace editing; set the option concerning to removing the trace after saving. activate Save line window; set output data representation (only for first trace); set Station code and Channel code; set sampling rate (only for first trace); set scale coefficient (only for first trace); set comments; create .wfdisc and waveform files.

Examples of automatic selection of two different traces: clean (a) and pure (b) visible

Selection of axis, segments (a) and futher digitization (b)

If the quality of the scanned image is good enough, the recursive segment selection will may not be required and well digitized trace may be formed during just one pass.

If the observed part of the seismogram is barely visible at the screen (trace is too pale) and the digitized line has been plotted far from trace (on User's opinion), one may apply a manual correction of this curve part. For this goal one must activate the mode Set points and pick a number of points instead of pale part of line, so a new curve will be plotted through the new points.

As soon as Set points mode will be set, a choice of approximation method Interpol will be prompted to User (linear interpolation or square spline approximation).

Picking must be performed from left to right. The first point must be as close to curve as possible. And so the last point must be on the drawn curve. After all points are picked, the User must set mode Edit trace to perform the approximation and then Refresh main window.

For more delicate approximation the User may perform this job in enlarged scale mode.

This manual correction process may be repeated as many times as required.
If the user found that the vertical grid lines substantially influence to the digitizing because of disarticulating effect, he should once click the Enhancing button, so the whole seismogram would be cleared from vertical grid lines.

 
 
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