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Program Manipulation

Time binding and setting variable time scale

The time binding is being achieved by (1) linking of one human time mark on the seismogram to the real astronomic time and (2) setting the variable (in common case) time scale in accordance with visible second (or other periodic) marks produced by a recorder's pen on the seismogram.

Tying the seismogram to astronomic time

To perform (1):

Switch a mode of the main menu to S HTM (set human time).
Find the only mark concerning to astronomic time on the seismogram set by an operator, and place a cursor onto this point.
Click the left mouse button. The dotted vertical line will be drawn through the image.
Input the time, figured near the mark, into the Hunan time command line in format 1993-098:12.14.35.000 and push the "A" button.  

If the line is drawn not enough exactly (on user's opinion), then the line (and Human time value) may be reset. For this purpose a user should switch the mode of main menu to "D HTM" (Delete human time), move cursor to the line and push the left mouse button. Then he must repeat setting (items above).

Setting the variable time scale

The manual time scaling procedure takes into account a nonuniformity (in general) of the paper motion in a recorder (one of the reason of this is the changes of the electric power supply). For this purpose the visible seismogram's time marks are used.

Another circumstance, which is accounted by authors, is that a visibility of the time marks is not always good enough through along the whole seismogram. Also, sometimes the time marks at the seismograms are anonymous, i.e. not accompanied by notes.

So the scaling procedure finds the neighbor second marks (or the wider interval with known duration) and makes the first scale estimation on the basis of this interval. Then the program extrapolates this scale outside the first interval and corrects it using another visible time marks.

In order to provide a maximum precision of time binding, the lines must be drawn through well visible time marks only. The number of time marks must be as much as possible.

To set the time scale, a user must switch the mode of main menu to "S TM" (set time mark lines). He can start scaling from an arbitrary part of the seismogram (as a rule it is the most clear part) and then move gradually to both sides of the image. Drawing the line is provided by moving the cursor into the corresponding point of the mark and clicking the left mouse button. The first interval between two time marks may have any duration (in integer seconds). After first two lines are drawn, the denote of the panel command line "TM interval" is highlighted and a user must set the number of seconds between these lines, and push the "A" button.

After user's confirmation, the estimated scale become valid outside the interval in both directions. If one chooses any third time mark outside the first interval, the new value of scale is computed for the new interval and for outer part of the seismogram in this direction.

If the new time mark value distincts more than 10% from integer value (in accordance with previously estimated scale) the program requests again a user's confirmation by the highlightening the "TM interval" command line. After confirmation the new scale is really set. This may be repeated while the user achieves a border of an image; the process may simply be stopped in arbitrary moment.

Once the User decides to step back during the process, he should take into account that all lines set before outer of planned line, would be deleted.
The control table of variable time scale, which contains a current setting scale parameters for further time estimation during the digitizing, is being displayed onto a console after each time-mark-line setting (see below).

There are total 200 index elements reserved for storing the user sampling step parameters. This table is filled starting from the middle element, which has a number 100.

Each element includes the index, X-coordinate of pixel (counted from the beginning of canvas), distance (in seconds) from the initial time mark line (from the middle index of a table), and average scale of the partial interval (in pixels per second). The example of such current table is shown below:

DELTA  =-0.971292  NUMBER  OF  LINES  =8,  LEFT_IND
=97,
RIGHT_IND =104

IND PIXELS UNITS  PIX_PER_UNIT_TO_LEFT
97)   390  -3           0.00
98)   593  -2           203.00
99)   802  -1           209.00
100)  1000  0           198.00
101)  1203  1           203.00
102)  1409  2           206.00
103)  1610  3           201.00
104)  1813  4           203.00

Note that human time setting is based upon the human timeline drawn at the seismogram; this procedure does not depend on scaling procedure described. After the both procedures are completed, the varying time scale is automatically bound to the absolute (astronomic) time.

 
 
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