White’s Electronics TDI - Manual (Page 19)

PulseScan TDI Owner’s Guide 9
GAIN -
What it does
Gain controls the sensitivity of the detector, and the range at which the detector
will hear a given target. It increases or decreases the amplification of the receive
signal. In other words, it determines how deep the detector will hear a target.
How to use it
Ground mineralization gets in the way of hearing target signals. This so-called
bad ground can be balanced out by a ground balance procedure (a form of
filtering) so that targets can be heard clearly. This process can be accomplished
more easily and effectively if the gain is set at an appropriate level.
Never assume that the higher gain is set, the deeper the detector will go.
Although environmental noise EMI (electromagnetic interference) can affect the
level of gain that can be used, the ground mineralization has the most influence
on how high the gain can be set for optimum performance.
By attempting to use more gain than the ground minerals will allow, the detec-
tor circuit can go into overload, and at that setting will not be able to operate
properly. In this situation, reducing the gain will allow the detector to be ground
balanced, and thus operate correctly.