Fisher Research Labs Gold Bug, Owner'S Manual

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TARGET DISPLAY and AUDIO
SIGNAL Indicator
The lower-left bargraph designates
SIGNAL strength only when operating in
Discrimination Mode.
The signal strength indicator at the bottom-
left of the screen indicates how large or
close the buried metal target is.
If all bars are illuminated, the target is
large or close to the searchcoil.
If one or two bars are illuminated, the
target is far away or small, or both.
DEPTH Indicator
When operating in Discrimination Mode, a
target’s location and size can be verified
using the PINPOINT control.
Press PinPoint to temporarily detect metal
without searchcoil motion, and a
monotone hum.
While holding the PinPoint button, the
DePTH indicator will appear. The
number beneath DePTH represents the
distance of the object, in inches, from the
searchcoil. The Depth scale is calibrated
to coin-sized objects. For objects other
than a coin, the numeric value is a relative
measure of the target’s depth.
AUDIO FEEDBACK
When a target is detected, the Gold Bug
®
will respond with two types of sound:
1. v.C.O. (voltage Controlled
Oscillator) is an audio response
with variable pitch and volume.
2. LOW or HIGH tone beeps.
In Discrimination Mode, targets which fall
into the zone along the arc whose
segments are shaded will be identified
with a LOW tone beep and solid segments
with a HIGH tone.
As the user sets the discrimination level
with the
+
and
-
buttons, he is determining
which targets will induce the low tone, and
which will be eliminated.
All targets’ audio responses in All Metal
Mode will be v.C.O.
V.C.O. (voltage Controlled Oscillator) is
an audio response which provides a good
feel for the target.
The stronger the target signal, the higher
the volume and the higher the audio pitch.
very weak signals will have the faintest
volume and lowest pitch.
For this reason, the use of headphones
is always recommended for detecting the
smaller and deeper targets.
2-DIGIT TARGET INDICATOR
In Discrimination Mode the 2-digit target
indicator, in the middle of the screen,
provides a specific target value to help
identify buried targets more accurately.
With practice in the field, you will learn to
associate target values with the probable
identification of buried objects. The target
value can vary each time the searchcoil
passes over the target, depending upon
the orientation of the object and its
distance from the searchcoil.
As a starting point, refer to the table below.
TARGET Readout
The table below lists some common
approximate
target values. With
experience in the field, you will recognize
many types of metal objects by their
numeric value.
OBJECT TARGET-ID
foil from gum wrapper 47 - 48
U.S. nickel (5¢ coin) typically 58
aluminum pull-tab 60 - 75
aluminum screw cap 70 - 80
zinc penny (dated after 1982) typically 78
aluminum soda pop can
75 - 85
copper penny, clad dime typically 83
U.S. quarter (25¢ coin), clad typically 85
50¢ coin, modern clad typically 87
old silver dollar coin typically 89
US silver eagle $1 coin typically 91
Caution:
The target indications are
visual references. Many other types of
metal can also be represented by a given
Target-ID
2. + and -
In Discrimination Mode,
+
and
-
change the level of discrimination (target
rejection)
CONTROL PANEL
GAIN versus THRESHOLD
“Gain” increases, or multiplies, the strength of signals from buried metal objects.
For maximum detection of the smallest or most deeply buried objects, increase
the Gain. To minimize the weakest signals, reduce the Gain.
“Threshold” controls the detector’s audio level. Positive threshold values
amplify the audio response of weak target signals. Negative threshold
values suppress sensitivity.
For searching at maximum sensitivity, first set the gain at a low level. Then
set threshold into the positive region, with a comfortable background-hum
volume level. Then increase Gain to a comfortable level, free of chatter.
For silent searching, set threshold to a negative number, and also reduce
Gain if necessary. Silent searching will result in the loss of some sensitivity.
TOUCHPAD CONTROLS
1. GROUND GRAB ® COMPUTERIZED GROUND BALANCING / PINPOINT
This button has a dual function, depending on the detection mode.
a. In DISC Mode, press-and-hold the button to activate PINPOINT.
Pinpoint temporarily engages a no-motion detection mode. Searchcoil
motion is not necessary to detect metal. Any metal within the searchcoil’s
detection field will induce a sound. Pinpoint is generally used to verify a
target previously detected in Discrimination Mode.
b. In ALL MeTAL Mode, press-and-hold the button to activate GrOUND GrAB
®
Computerized Ground Balancing.
Ground Grab
®
Computerized Ground Balancing allows you to set the
detector’s internal ground setting equal to the phase of the ground you are
searching over. See the section on Ground Balancing for a more thorough
explanation of this feature and the reason for using it.