Depth - Fisher Labs Gemini-3 Operating Manual

DEPTH

The GEMINI-3 was designed to locate large, deep objects such
as an iron chest, pipe or an ore vein. It will not detect small coin-
sized objects. A quart jar full of coins, however, may be detected
one-to-three feet deep. A 55-gallon drum may be detected as
deep as 10 feet. A very large object, like an automobile, may be
detected at 20 feet or more.
The ability of the GEMINI-3 to detect objects at various depths
depends on several factors:
1. Ground Mineralization: The penetrating power of the
2. Size and Depth of Object: A 4-inch diameter target
3. Length of Time Object is Buried: An object that has
4. Shape of an Object: Ring or looped shaped objects
5. Operator Skill: Probably the most important factor of
GEMINI-3 is adversely affected by the presence of
magnetite (a black iron oxide) and wet conductive
mineral salts. For example, an object that can be
detected at 15 feet in neutral ground may be
detected no deeper than 5 feet in highly mineralized
ground.
will produce signal 64 times stronger than a similar
1-inch diameter target at the same depth. An object
1-foot underground will produce a signal 4,000 times
greater than the object 4 feet deep.
been buried for a long time may be easier to detect
than a newly buried object. Rust and other oxides as
well as mineralization caused by the interaction of
the metal with soil chemicals are good conductors
and aid detection.
lying flat produce the best results. Flat or dish shaped
targets are also easy to detect. Rod shaped objects,
especially when scanned on end, are very difficult
to detect.
all, practice over known buried targets is essential.
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