User's Manual

pulseEKKO PRO 3-System Setup Parameters
39
3.2.6 Radar Velocity
If an accurate depth axis on the real-time display is desired, or the user wishes to see the approximate
depth of penetration while setting the time window value (Section 3.2.2: P35), the user should supply the
program with the average radar wave propagation velocity (in m/ns or ft/ns).
The best way to determine the radar velocity of the survey area is to extract the velocity using the
Hyperbola Curve Fitting routine (Section 5.5.4.1: P75) or a Common Mid Point (CMP) survey (Section
6.11: P91).
Note that having an incorrect radar velocity value does NOT affect the quality of the GPR data collected. It
will only affect the depth scale on the display. This can be changed later.
If it is not possible to determine the radar velocity directly, refer to the chart below which lists the radar
velocities of various materials.
A velocity of 0.1 m/s or 0.33 ft/ns is a good value to use when uncertain about the velocity of the material
being surveyed.
Material Velocity (m/ns) Velocity (ft/ns)
Air 0.30 0.98
Ice 0.16-0.17 0.52
Dry Soil 0.15 0.49
Dry Sand 0.15 0.49
Granite 0.13 0.43
Dry Salt 0.13 0.43
Dry Rock 0.12 0.39
Limestone 0.12 0.39
Wet Rock 0.10 0.33
Concrete 0.08-0.12 0.26-0.39
Pavement 0.10 0.33
Shales 0.09 0.30
Silts 0.07 0.23
Wet Soil 0.06 0.20
Wet Sand 0.06 0.20
Clays 0.06 0.20
Fresh Water 0.033 0.11
Sea Water 0.033 0.11