Radiodetection RD1000 Operation Manual page 25

3.5.4 Gain
Since GPR signals are absorbed by the material being scanned,
deeper targets have weaker signals. Gain acts like an audio volume
control, amplifying the signals and making deeper targets appear
stronger in the image. The Gain varies from 1 to 9 with 1 being no
gain and 9 being the maximum gain.
As the Gain changes, the current image on the display updates so it
is not necessary to re-collect an image with a different gain setting.
Use the lowest gain setting that shows the targets. Try to avoid
over-gaining as understanding the image may become
more difficult.
Figure .1: gain
adjustments
RD1000™ Operation Manual 5