By Chris Gholson
From page 56 of the March, 2011 issue of Lost Treasure
Copyright © 2011 Lost Treasure, Inc. all rights reserved
Anyone that has been involved with metal detecting for any length of
time will have undoubtedly heard the name Garrett.Garrett has done
wonderful things for the industry in four decades by supplying quality
detectors and through their efforts to help promote the hobby. Their
products have been responsible for finding millions of dollars worth of
ancient coins, relics, jewelry and gold nuggets, and are revered by
treasure seekers.In addition to the hand-held products, Garrett produces
a range of detectors for use in security screening, crime scene
investigation and for military de-mining operations. One of the newest
additions to their consumer line is a detector known as the AT Pro.The
AT Pro (ATP) is a VLF detector, which operates at approximately 15 kHz
and is outfitted with a waterproof 8.5" x 11" elliptical Double-D coil.
The machine weighs in at roughly 3.2 pounds and is powered by four AA
batteries. It features an updated panel with an LCD screen and all
pushbutton controls.But what really sets this machine apart is its
versatility. It is a true multi-purpose detector that has the ability to
locate all types of buried treasure-coins, relics or gold. And with
its unique All-Terrain design, this machine can be used just about
anywhere.The entire detector can be submerged under water to a depth of
10 feet! With this level of weatherproofing, the ATP is an excellent
choice for streams, ponds, or in shallow water.The ATP includes
Garrett’s exclusive Target ID technology and patented discrimination
features. It offers six detection modes, which can be adjusted using the
MODE button-three STANDARD and three PRO.The Standard detection modes
include: Custom, Coins and Zero. The Pro modes also include: Custom,
Coins and Zero.The difference between the Standard and Pro modes has to
do primarily with a target’s audio response. In all three Standard
modes, the detector provides a full-strength binary audio response
regardless of the target’s size or distance from the coil. In other
words, while hunting in any of the Standard modes, the detector will
make a beep when passed over a metal target. The pitch will vary
depending on the conductive properties of the target, but it will be
just a beep.The Standard modes offer quieter, more stable operation and
may be a good place for new users to start while familiarizing
themselves with the detector.However, to truly unlock the power of the
ATP, the user will want to explore the Pro modes. The benefits of these
modes include the ability to hear and determine a target’s approximate
size and depth via the Proportional Audio and Tone Roll Audio.Pro mode
also offers faster recovery speeds for separating targets that are in
close proximity. The advanced audio features of Pro mode are intended
for skilled users who wish to hear the signature of targets versus the
simpler target response provided in Standard. Basically, the Pro mode
will allow you to hear targets as they really are.For example, if there
is a coin near the surface, the detector will produce a loud signal
response. If we take that coin and bury it at six inches, the signal
produced will be weaker, thereby telling the operator that the target is
a reasonable distance away from the coil. Whereas in the Standard
mode, the detector will give the same type of signal response whether
the coin is near the surface deeper.As mentioned, there are six
operating modes to choose from. The ZERO Mode is essentially an
All-Metal mode. There will be no discrimination and all metals will be
detected. This is a good option for relatively clean, trash-free
ground.The COINS mode can be used to find most types of coins and
jewelry, while eliminating many trash targets like iron and foil. In
this mode, the discrimination level has been preset to 35 and one notch
that is associated with foil has been excluded. Pull-tabs have not
been eliminated because they have properties similar to small coins and
jewelry. This mode will be a good choice for those that like to hunt
parks, playgrounds, or perhaps along the beach.The CUSTOM mode has been
left open for the user to customize. The factory preset for this mode
is the same as ZERO. Any changes or adjustments made in CUSTOM will be
retained after the detector has been switched off. Changes made to the
ZERO or COINS modes will not be retained.The Digital Target ID system
found on the ATP provides a specific value to help the user identify
targets more accurately. Unknown targets are identified in the LCD with
a number. This number is a representation of the target’s conductive
properties. Numbers closer to 1 are the most ferrous; numbers closer to
99 are the most conductive. The Digital target ID number can be used
in conjunction with the Target ID Cursor, which is found just beneath
the Target ID Legend.The Target ID Cursor will move along the Target ID
Legend and settle on the place that best represents the target found.
Ferrous targets show up on the left half, non-ferrous targets that are
lower in conductivity will show in the middle, and highly conductive
targets will show on the right half. The Digital Target ID is more
precise than the Target ID Cursor, however, when used together, it is
fairly easy for the operator to get a general idea of what type of
target has been detected.Another way for the operator to quickly
determine the probable identity of a target is by listening to the
audio tone. The ATP is equipped with a Tone ID feature that produces
three distinct tones based on a target’s composition and conductivity.
Low tones indicate ferrous items, such as nails, wire, boot tacks, etc.
Medium tones indicate small or thin non-ferrous items. Including gold
nuggets, foil, small jewelry, and some hammered coins. High tones
indicate non-ferrous targets with medium to high conductivity, such as
most coins and larger jewelry.The ATP can be ground balanced manually
and automatically. Ground balancing is a crucial part of detecting and
must be done every time the machine is turned on. Sometimes, if
conditions are severe, it may be required several times a day. Persons
that do not take the time to ground balance will leave good targets
behind.The automatic ground balance procedure is quick and was my
preferred method. To balance, simply find a clean piece of ground free
of metallic targets. Push and hold the GND BAL button while pumping the
search coil towards the ground. If the machine is out of balance you
will hear a noise when the coil is lowered or pulled away from the
ground. Continue to hold the button until there is very little change
in audio when the coil is moved. In some cases, the manual setting may
achieve a more precise balance, but it is not recommended for new
users.The ATP has eight sensitivity settings shown on the LCD. I
recommend using the highest sensitivity setting, as this will allow
smaller and deeper targets to be found. However, the level used will
ultimately be determined by the conditions present in the area. High
settings can be used when hunting ground with low mineralization and
electromagnetic interference (EMI). Lower settings may be required if
the ground mineralization is severe, or there are high levels of EMI.If
you find the detector is behaving erratically, try re-ground
balancing. If this does not alleviate the problem, try lowering the
sensitivity. If this still does not solve the problem, you may need to
adjust the frequency. The ATP has the ability to slightly alter its
operating frequency to help combat noise caused by power-lines, other
metal detectors, electric fences, etc. There are four slightly
different frequencies to choose from. These adjustments are small and
will not affect detection performance.As far as discrimination goes,
the ATP has plenty of it. It features a high-resolution iron
discrimination adjustment called IRON DISC. This feature is adjustable
from 0 to 39. Low settings offer less iron discrimination, while high
settings will eliminate more iron. The user should never apply more
discrimination than is necessary; otherwise the detector may mask a good
target that is in close proximity to a bit of iron.In addition to the
high-res Iron Discrimination, there are also 12 "notches" available
This is called Notch Discrimination and can be used to eliminate trash
targets. Any combination of these can be switched on or off. We will
not discuss them in detail simply because I feel they should be used
with caution.Turning off a notch in the wrong place could cost the user
a nice piece of gold. I found this when passing a nugget across the
coil and intentionally hitting the ELIMINATE button. When I ran the
nugget across again there was no target response - the nugget had been
eliminated!For gold prospecting, I would recommend that none of the
notches be eliminated. Instead, I found myself relying more on the IRON
DISC. With this I could run at fairly high levels (25-30) with very
little risk of ignoring a nugget.In order to test the gold finding
capabilities of the ATP, I took it deep into the mountains of central
Arizona. I chose this area because I had found gold there in the past,
and because much of the ground was shallow with little trash. I started
off in a mid-sized wash that meandered through the hills for nearly a
mile with exposed bedrock full of cracks.I opted to start in the Pro
Zero mode first. I increased the Sensitivity to its maximum level and
began the ground balance procedure. I quickly discovered this setting
was too high and could not cope with the abundant black sands and hot
rocks. After dropping the sensitivity to four and re-ground balancing,
the ATP ran smoothly. EMI was not a problem, so there was no need to
adjust the Frequency.My first target came within five minutes. It
produced a medium pitched signal and a Target ID of 40. My excitement
grew when I increased the IRON DISC to a 25 and the target still rang
true. Fortunately, I didn’t have to dig much of a hole before
discovering it was only a .22 bullet. At least I knew all was working
well with the unit.The next two targets I found were a bit out of the
ordinary for a remote location. I swung the coil upwards towards the
bank and got a loud, high-pitched signal. While attempting to pinpoint
it, I picked up an equally strong signal about five inches away. Neither
was affected by the IRON DISC and both gave high Target IDs, ranging
from 75-80.The ATP told me they were coins, but I had a hard time
believing there were coins this far from town. After digging them out I
found the ATP had not lied. One was a 1976 penny and the other a 1981
dime.I walked nearly a quarter mile more of the wash and only passed
over the occasional target that was obviously iron. These signals gave a
low Target ID, usually in the 20’s, and would only trigger a broken
signal or no signal at all. I dug a few of them just to be safe and
found all were nails or fragments of iron.I was considering moving to
new spot when I received a mellow, but definite signal from a piece of
bedrock. It was not strong and I believe if I had been swinging the coil
any faster I would have missed it. It gave a medium pitched tone with a
Target ID that wavered between 35-40 and was not affected by the
discriminator. Things were looking positive, but I knew it could be
another bullet.The rock was fractured and it was difficult to determine
which crack the signal was coming from, so I made use of the PINPOINT
feature. This allowed me to stop the coil directly above the target
without losing it.I chipped away until there was nothing left but broken
bedrock and sand. Finally, I spotted the source - it was indeed a
nugget! Although the piece weighed nearly one gram, and had only been
concealed by an inch or so of material, it did not give the strong
signal I would have expected. The only explanation I came up with was
that it must have been turned on edge.I found the ATP a pleasant machine
to hunt with. Some of its strong points were: easy operation, light
weight, automatic ground balance, highly versatile, and extremely
weatherproof. The ATP is a true All-Terrain detector that can be used on
land, in the water, in the mud, or even snow.I did not have the
opportunity to test it underwater, but have been reassured the entire
detector can be taken up to 10 feet deep, providing the supplied
headphones are not submerged. Optional waterproof headphones are
available.The biggest con in my opinion was the lack of a Threshold. The
threshold is a constant background "hum" emitted by the detector. The
ATP is a silent search machine, which means no sound will be heard
unless a target is found. I know there are hunters that prefer silent
search detectors, but I am not one. The humming of a threshold can be
annoying, but that hum is packed with valuable info.Often a small, or a
deep nugget, will not produce a clear, distinct signal. Many will only
trigger a slight waver in the threshold and a silent search machine
could miss them. I don’t mind the extra noise and, if Garrett decides to
release an updated model, I hope they consider the addition of an
adjustable threshold.I would also ask for an adaptor that would allow
different brands of headphones to be used, and a backlight in the LCD
would have been a nice addition.The new AT Pro is a unique detector with
something to offer every hunter. It can be used for all types of
detecting and can be taken just about anywhere.At only $699.95, it
offers versatility and performance at a reasonable price. It comes with a
full 2-Year Warranty and is made right here in the USA.