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If you really want to examine the data, sample by sample value, then use the program traplt. This program generates an old school lineprinter type listing. In addition to a plot of the signal, you also get a frequency spectrum. Let's say we wish to examine the first major trough in trace 41, using bplt, we might execute this command:
bplt twav.seg 1 1 0 41 41 .05 .06 2 1500 300 5 2
That would produce a plot as shown in Figure 4.
However, if we wish to see the actual sample values (in this case, in units of
volts), we execute
the following command:
traplt twav.seg 0. .2 41 0 1
and page down to samples 251 through 300. This is the large negative also
visible in Figure 2
![\includegraphics[scale=1]{FigureD}](img9.svg)
{listtraplt}
max= 0.6539936E+03 min=-0.1014899E+04
j x(j) .....................................................
251 0.3774579E+02 | .* |
252 0.1636029E+02 | * |
253 -0.5172668E+01 | * |
254 -0.2949243E+02 | *. |
255 -0.5731537E+02 | **. |
256 -0.8488977E+02 | ***. |
257 -0.1139543E+03 | ****. |
258 -0.1435989E+03 | ****. |
259 -0.1739700E+03 | *****. |
260 -0.2052856E+03 | ******. |
261 -0.2369359E+03 | *******. |
262 -0.2657293E+03 | ********. |
263 -0.2946696E+03 | *********. |
264 -0.3198569E+03 | **********. |
265 -0.3436373E+03 | **********. |
266 -0.3639295E+03 | ***********. |
267 -0.3823533E+03 | ************. |
268 -0.4009266E+03 | ************. |
269 -0.4172845E+03 | *************. |
270 -0.4305879E+03 | *************. |
271 -0.4431530E+03 | *************. |
272 -0.4572617E+03 | **************. |
273 -0.4737784E+03 | **************. |
274 -0.4913515E+03 | ***************. |
275 -0.5107348E+03 | ***************. |
276 -0.5340413E+03 | ****************. |
277 -0.5633405E+03 | *****************. |
278 -0.5983062E+03 | ******************. |
279 -0.6352686E+03 | *******************. |
280 -0.6775207E+03 | ********************. |
281 -0.7210417E+03 | **********************. |
282 -0.7679259E+03 | ***********************. |
283 -0.8153746E+03 | *************************. |
284 -0.8634789E+03 | **************************. |
285 -0.9100562E+03 | ***************************. |
286 -0.9509911E+03 | *****************************. |
287 -0.9814030E+03 | *****************************. |
288 -0.1004137E+04 |******************************. |
289 -0.1014899E+04 |******************************. |
290 -0.1012347E+04 |******************************. |
291 -0.9976479E+03 |******************************. |
292 -0.9661345E+03 | *****************************. |
293 -0.9193480E+03 | ****************************. |
294 -0.8567044E+03 | **************************. |
295 -0.7788740E+03 | ***********************. |
296 -0.6881360E+03 | *********************. |
297 -0.5870426E+03 | ******************. |
298 -0.4769774E+03 | **************. |
299 -0.3637875E+03 | ***********. |
300 -0.2464730E+03 | *******. |
.....................................................
TMIN= 0.000 TMAX= 0.200 TRACE= 41 DELT=0.0002 FILE: twav.seg
listtraplt
The above example illustrates how one may sort out digital clipping from plotter clip. Trace 41 was recorded at a depth near 840 m elevation. In Figure 1, this first major trough appears clipped. This is only plotter clip, due to the choice of plotting parameters. Figures 2 and 4 show that one could choose other parameters for bplt to investigate the question of clipping. However, traplt takes us right to the sample values themselves. Data which have been digitally clipped are quite different. Such data clipping occurs when the signal is too large for either the geophone or the amplifier. Then a sequence of samples will have identical values out to the precision of the A/D converter. A quick way to quality check for digital clipping is to integrate the data. Clipped data will drift either positive or negative when integrated . You can integrate data with the program bint.