User's Manual

4-Running in Scope Mode pulseEKKO PRO

4.1 Scope Screen

A sample of a screen data plot while in Scope mode is shown in Figure 4-2. The radar amplitude (in

millivolts) is plotted in the vertical axis while the time axis is plotted in the horizontal axis. The length of the

time axis depends on the Time Window value. Each division in the time axis is 10% of the length of the

Time Window. In the case shown in Figure 4-2, the Time Window is 100 ns so each division is 10 ns wide.

Below the plot, the vertical amplitude scale, trace number, time window, sampling interval (DeltaT),

timezero offset, number of points, stacks and frequency are listed. It also indicates that the data trace is

being filtered with a 25 point DEWOW filter (see Appendix B: GPR Signal Processing Artifacts).

Pressing the START button begins data collection. The STOP pauses acquisition and displays a menu

with further options.

Figure 4-2: A sample of a screen data plot while using Scope mode. The parameters below the graph, the trace number, time win-

dow, sampling interval (DeltaT), points, stacks and frequency are listed (Section 3: P31). The Offset parameter listed is explained

below.

The Offset is the value used to adjust the first break to the ideal region. The value has no importance to

the radar data; it is only used for the adjustment of the initial radar pulse to the desired position within the

time window. It compensates for changes in cables and differences in electronic components.

4.1.1 Adjusting Timezero (Offset)

Assuming that data are coming in, the first step is to ensure ‘timezero’ is in the correct location. Timezero,

for our purposes, is defined as the first arrival of the radar wave; it is used as a convenient reference

starting point for the trace, hence the name: timezero.

Timezero should be located near the beginning of the second vertical division on the screen (Figure 4-2).

Locating timezero to the right (further in time) of the second division has no ill effect on the data, it just

means possible reflectors may be lost off the bottom of your recording window. Locating timezero to the

left of the second division should be avoided.