User Manual

Geophysical Survey Systems, Inc. Model 4108F Antenna
System Settings and User’s Notes
MN34-550 Rev A
4
Gain: Data collection gain for the 4108F antenna should be adjusted so that the peak amplitude
of the pavement surface reflection is approximately 2/3 of the total screen width. For example, in
Figure 2 the pavement surface reflection has an amplitude of approximately 20000 and the full
screen width is 32000. Using the filter settings described in Table 1, a gain of 13-14 dB is typical
for most pavement surfaces. However, for more highly reflective surfaces, such as concrete, the
user may have to decrease the gain value. It is very important that the pavement surface
reflection amplitude (and metal plate reflection when performing calibration) never reach
its maximum. Figure 3 shows an improperly gained signal.
Figure 3: Example of Model 4108F data scan collected with too much gain.