Depth & Discrimination - Whites Coinmaster GT Owner's Manual

same responses as foil, nickels, and pull tabs. Likewise, pull
tabs often look like nickels and vice-versa.
Target ID is by no means foolproof and should be consid-
ered only a probability estimate. As we'll see in the next sec-
tion, the probability decreases with depth. An excellent
approach is to work with test targets (especially planted at dif-
ferent depths) to get familiar with target responses.
Depth and Discrimination
The CoinGT has both audio and visual target ID, as well as
the ability to reject certain ranges of targets. It is important to
understand the limitations of target ID — and, because it is
based on target ID, discrimination — to avoid missing good tar-
gets.
As explained in the section on VDI, target ID is based on
the phase shift of a target's received signal. We've already seen
that many different types of targets can share VDI responses.
Depth also plays a role. A strong target signal (either from a
shallow target or a large target) provides for a strong and repeat-
able phase response from which we can extract a pretty reliable
VDI. As the target signal weakens, its VDI becomes less reli-
able. This can show up as an inconsistent target response as the
coil is repeatedly swept over the target. It is not unusual for
deep targets to produce an inaccurate target ID, and perhaps
even cross over into a rejected zone.
Furthermore, ground mineralization can cause errors in tar-
get phase. Even targets of moderate depth can produce an inac-
curate target ID if ground mineralization is severe enough.
Reliance on target ID should be tempered, and discrimina-
tion should be used with care. A "test garden" with multiple
types of targets buried at various depths is a good way to see
how target responses behave and to hone your skills in reading
these responses.
Coinmaster GT
Page 11
Owner's Manual