Recommended for most hunting environments
What’s a VLF metal detector?
The most commonly-used metal detectors are Very Low Frequency (VLF) models, which continually transmit energy at a single powerful frequency, generally ranging between 3 kHz and 30 kHz.
Advantages of VLF Detectors
Most soils you will search contain only light to moderate mineralization. In these environments, the single frequency of a VLF offers greater depth capabilities, enhanced Target ID, and better discrimination. VLF detectors are also very energy efficient and are less susceptible to external noise and interference.
In short, it is the most appropriate technology for detecting the broadest range of targets over the most common ground conditions.
Things to Know About VLF Detectors:
- VLF metal detectors are also commonly referred to as Single-Frequency or Continuous Wave detectors.
- Saltwater environments and heavily mineralized soils can cause a loss of detection depth and Target ID accuracy. Pulse induction detectors are often favored here.
- Lower frequency detectors tend to be more sensitive to more highly conductive metals such as silver or brass. Higher frequencies are generally more sensitive to lower conductivity metals such as gold, platinum, and lead.
VLF Tip: Ground Balance Feature
Soil mineralization levels often change in the field, and this can create unstable detector performance. Higher-end detector models with Ground Balance features allow the user to adjust the detector’s ground balance as these conditions change. Ground balancing a detector calibrates it to the soil conditions, resulting in deeper target detection, more accurate target information, and stable detector operation.
PULSE INDUCTION (PI) DETECTORS
Recommended for heavily mineralized ground and saltwater environments.
Advantages of PI Detectors
Pulse detectors provide the best performance over mineralized ground and in saltwater environments due to their ability to ignore minerals by virtue of their pulse characteristics.
Iron Check Techniques
To help determine if a target is ferrous (iron), some users employ a reverse discrimination technique to check the item. With either Garrett pulse detector, simply increase Discrimination to maximum. If the target still produces a substantial signal, there is a good chance it is iron.
The Garrett ATX additionally offers a true Iron Check feature that produce a low-tone growl sound (Iron Audio) for many iron items.
Things to Know About Pulse Induction Detectors:
- Pulse induction metal detectors are also commonly referred to as multiple frequency detectors.
- Target ID accuracy is reduced or nonexistent as compared to a VLF detector.
- Less energy efficient than VLF detectors, requiring more batteries and/or more frequent battery changes.
- More susceptible to external noise (EMI) and interference.
All PI detectors cancel most of the saltwater response by nature of their operation. In some of the more challenging saltwater environments when operating a Garrett Sea Hunter, you can add a small amount of Discrimination (or Delay) to cancel out the remaining saltwater response. With a Garrett ATX, however, it can be quickly ground balanced to the saltwater to provide the smoothest audio threshold and performance.
TECHNOLOGY, FEATURES: AT Gold, AT Pro
PROPORTIONAL AUDIO FEATURE
The AT Gold and AT Pro feature advanced, proportional (Pro) audio modes. This allows the user to hear subtle changes in a target’s response. Proportional audio also helps the user to better judge a target’s size, shape and depth and has the additional benefit of a much faster recovery time when detecting adjacent targets.
The AT Pro also includes three Standard audio modes, which provide a full-strength beep regardless of a target’s amplitude. Many detectorists prefer this simpler, binary (either on or off) target response.
HIGH-RES IRON DISCRIMINATION™
With adjustable levels of iron discrimination (40 points on the AT Pro and 44 points on the AT Gold), the user can apply only the minimal amount of discrim needed to reject iron trash targets. The detector will continue to find desirable targets that might otherwise have been “masked” by iron.
DIGITAL TARGET ID (0 TO 99 SCALE)
This scale on the LCD screen helps to more precisely identify buried targets. Items with a value near 1 are the most ferrous, while the most conductive targets (such as thick silver) register closer to 99 on the Digital Target ID.
IRON AUDIO™ AND ALL-METAL IRON AUDIO
Iron objects can mask good targets or create “ghost signals” that appear to be good. Garrett’s selectable Iron Audio feature allows the user to hear discriminated iron (normally silenced) to help avoid being tricked into digging an undesired target.
For many detectors, bottle caps, steel washers, etc. sound like good targets, producing a high tone response. The bottle cap’s shape and flat surface resembles a coin, which tricks the detector. With Iron Audio however, the bottle cap will produce a very distinctive response with multiple tones, compared with a coin’s high-tone response.
The AT Gold also feature All-Metal Iron Audio to identify problematic iron targets while in a True All-Metal Mode, another Garrett exclusive!
TONE ROLL AUDIO™
Provides more audible target information to help identify targets, particularly iron. Detectors with binary audio produce a single target tone based on the target’s strongest signal. Tone Roll audio provides a variance of target tones as the searchcoil approaches, passes above and departs from a target. These varying phases provide better overall target information.
This AT Gold feature allows the user to select 33 levels of constant background audio (“hum”). By operating with a barely audible threshold level, this feature helps to maximize the user’s ability to hear faint signals thereby maximizing detection depth.
Garrett AT detectors are engineered with waterproof housings and connectors to protect in dusty, muddy, wet and humid environments. They can be submerged to a 10-foot depth (maximum).
Note: Waterproof headphones must be used if the headphones are submerged in water. The standard headphones provided with the AT Pro and the AT Gold cannot be submerged, however the cord leading to the headset is submersible.
GROUND BALANCE OPTIONS
Each AT detector has both manual and automatic ground balance features to allow the user to reduce the detrimental effects of ground mineralization. The AT Gold additionally offers Ground Balance Window, a Garrett exclusive feature allowing the user to simultaneously ground balance to a range of values. This smooths out the All Metal Audio by reducing the subtle ground responses and allows the user to better hear faint target signals.
HOW SEARCHCOILS WORK
Understanding the basics of searchcoils will empower you with the ability to choose the best searchcoil for each application. Searchcoils generally consist of two internal sets of coiled wires, a Transmit coil (TX) and a Receive coil (RX). Mono coils can be different in that one coil acts as both the TX and the RX. When the detector is turned on, the TX coil generates a magnetic field in the surrounding space.
When a metallic object is within this generated magnetic field, it will create a distortion in the magnetic field. The RX coil will sense this distortion and send a signal to the control housing.
As a rule of thumb, the detection depth of a searchcoil will be approximately equal to its diameter, for a coin-sized object.
As a searchcoil’s size increases, its field pattern becomes larger, less concentrated and it begins to miss small objects. For a coin-sized object, this effect becomes noticeable when using searchcoils larger than about 15″ in diameter.
SEARCHCOIL SHAPES AND SIZES
To help determine the best searchcoil size and shape for your needs, consider the hunting environment in which it will be used and the targets being sought.
- Elliptical Searchcoils—more maneuverable than a circular searchcoil. Provides greater coverage than a circular coil due to its elongated length.
- Circular searchcoils—most commonly used shape. Provides slightly more detection depth and sensitivity in non-mineralized soil. Searchcoils also come in a 2-box configuration, which are used for detecting deeply buried targets.
Small Searchcoils (Less than 6″ diameter)
- Concentrated magnetic field; the best choice for hunting in areas with a lot of metal debris.
- Ideal for detecting very small objects.
- Less coverage per sweep; more scans required.
Medium Searchcoils (8″-9″ diameter)
- Best choice for general-purpose hunting (including coins and coin-sized targets).
- Provides the best combination of magnetic field concentration, detection depth and capability to detect the greatest range of target sizes within the detection area.
- Lightweight and easy to maneuver.
Large Searchcoils (More than 9″ diameter)
- Provides greater depth and coverage due to wider and deeper magnetic fields.
- Best choice for hunting targets that are large and deeply buried, such as caches and large relics.
- Larger scan area can be a problem in trashy areas where the searchcoil is detecting several targets at once.
MULTIPLY YOUR FINDS WITH THE RIGHT SEARCHCOIL
There are five basic searchcoil configurations: Concentric, Mono, Imaging, DD and 2-box. Hunting applications and ground conditions help determine which is the best choice for you.
- TX and RX are usually arranged as shown.
- This configuration provides the largest possible detection field and greatest detection depth, making the concentric coil potentially the most sensitive configuration available.
- Provides the most symmetrical detection field, allowing ease in pinpointing and consistency in target identification.
- Unfortunately, this configuration is the most susceptible to interference from ground minerals, resulting in substantial performance loss over heavily mineralized ground.
- Variation of the concentric configuration. Can be made with the TX and the RX coils located together or as a single coil acting as both the TX and RX.
- Detection and performance characteristics of mono coils are essentially the same as concentric coils.
- Both TX and RX are in the shape of a “D”.
- Provides greater detection depth and performance in heavily mineralized ground and saltwater.
- A long, narrow detection field runs beneath the DD’s overlapping center section from front to back.
- The DD configuration is less sensitive than a concentric searchcoil of the same size, over non-mineralized ground or in air testing.