Whites TDI SL Owner's Manual page 15

With
Ground Balance
gets will give an audio response, either a high or low tone. New
users are encouraged to use this setup and practice with various
targets to learn their audio responses. A US nickel or small gold
nugget works well for a low conductive target, and a US quarter
makes a good high conductive target. TDI is a motion detector,
so target responses depend on the motion of the coil. If you hold
the coil steady over a target, the audio response will fade back
to the threshold tone.
In some cases there is not enough mineralization to require
ground balancing (e.g. non-mineralized beaches), and
may be turned off. In this mode the audio response is
Balance
high for all targets.
In cases where you have determined that you definitely
need only one of the conductivity modes and not the other, you
will often find that switching to that mode reduces the amount
of audio noise (chatter) and allows you to run a higher gain. To
better illustrate this, let's use a strictly inaccurate but useful dia-
gram. The following is a representation of the audio response,
including a low conductor response, a high conductor response,
and random noise:
The ideal no-noise response is what you would get if you dis-
connect the search coil. With
thing above the ideal response will have a high tone and
anything below the ideal response will have a low tone. If there
is a lot of EMI or the
in a lot of audio chatter.
TDI SL
Owner's Manual
= and
On
Low-conductor
response
Noise
Target Conductivity = ALL
is set aggressively high this can result
Gain
Page 15
Conductivity Mode
Target Conductivity
= , all tar-
All
Ground
Ideal no-noise
response
High-conductor
response
= , any-
All