Groundtech A2: A Technical Look at the App, 3D Ground Scanner, and Metal-Detecting Capabilities

The GroundTech A2 integrates a pulse-induction (PI) metal detector, a 3D ground-imaging scanner, and the G-Portal companion app (iOS/Android). It is designed for deep anomaly mapping and target confirmation in mineralized soils, where conventional VLF detectors often struggle.

I evaluated an A2 after an organization hired me to locate a lost cache had already purchased the unit. The team had limited experience with cache hunting, metal detectors, and 3D scanners, so I conducted an independent field assessment. I have prior hands-on experience with other brands of metal detectors and 3D ground scanners, and I was interested in how the A2 performs and whether its capabilities justify the price.

GroundTech A2 as the Ground Scanner

Groundtech A2 System Overview

• Hybrid engine: Integrated pulse-induction detector (1 kHz) + MFS-3 dual-sensor gradiometer for magnetic field mapping. This pairing lets you both detect and visualize subsurface anomalies.
• Scan modes (six): 3D Ground Scanning, Live Scanning, Pinpointer, Detector Quick Scan, Detector Advanced Scan, and 3D Detector Scanning.
• Depth envelope: Developers/Company claims up to ~20 m in 3D scanning (highly dependent on object size and soil).
• Onboard + mobile analysis: Results appear on the A2’s built-in screen and can be analyzed in real time and in 3D on the G-Portal app (Bluetooth 4.2 BLE).
• Platform details: 240 MHz CPU with 12-bit A/D, device UI in 11 languages; the mobile app supports 25 languages.

A2-GEO variant: adds a geo-electric (resistivity) system with automatic/manual resistivity scan modes and a 100 V/66 mA output for deeper void/water/tunnel investigations; kit includes probes and cables.

Sample of 3 of the 6 Scanning Modes

Groundtech A2 Unit, Case & Accessories

Headphones That Come With the Groundtech A2

The G-Portal App – Needed to Use the Best Features of the A2

GroundTech’s G-Portal turns your phone/tablet into a 3D analysis station: connect, run scans, and review anomalies with full 3D visualization. It exposes the A2’s scanning modes (e.g., 3D Ground, Live, Pinpointer, Quick Scan) and supports device switching across GroundTech models. Available on iOS and Android.

Practically, you use it to:

1. Start a scan (grid or live) and watch color-coded 3D volumes of metals/voids develop.
2. Tag, save, and compare passes; repeat from a second axis to confirm shape/extent.
3. If you have A2-GEO, run a confirmatory resistivity pass over the same grid to cross-validate anomalies.

Field Notes From Testing

The G-Portal mobile app exceeded expectations: it’s well-coded, has an intuitive UX, and pairs reliably with the A2 over Bluetooth. In testing, it reconnected seamlessly after deliberate disconnects. 3D ground scans display in real time and are immediately available on the phone. Local file storage lets you step into an air-conditioned vehicle on hot days to review results instead of standing in the sun. Files can be saved locally and are easy to retrieve for reanalysis.

From an operational standpoint, the app’s rich controls—allowing deeper A2 tuning than the on-device interface—materially improve workflow efficiency.

The 3D Ground Scanner (MFS-3 dual sensor)

The MFS-3 is a magnetometer/gradiometer module in the A2 family with a ±3000 µT dynamic range, designed to measure spatial variations in the Earth’s magnetic field. By resolving small differential changes in magnetic intensity, it delineates large ferrous masses and magnetically enhanced soils (e.g., fired or disturbed sediments), making features such as walls, foundations, tunnels/chambers (via disturbed/backfilled signatures), and rooms visible that a conventional metal detector may miss. In practice, the MFS-3 is used for gradiometric mapping to pre-identify void-related indicators and structural anomalies, as well as large ferrous disturbances, before committing time to coil sweeps.

A2 Unit with the Scanner

Testing Finding Buried Caches Using the 3D Ground Scan Mode

In the photos and screenshots below, we buried a coin cache consisting of 100 U.S. quarters (in paper rolls, placed in a small box inside a nylon bag) at ~12 inches (≈30 cm) in a freshly tilled field. Using the GroundTech A2 in 3D Scanner mode, the target produced only a weak, low-contrast anomaly—visible as a faint, non-coherent hotspot on the heat map. The response was not repeatable or sufficiently distinct from background noise and soil disturbance, making interpretation ambiguous.

Conclusion: Based on this test, I would not recommend the GroundTech A2 for locating small coin-roll–scale caches at ~12″ in disturbed soils. The combination of non-ferrous currency, distributed geometry (multiple narrow rolls), and heterogeneous, tilled ground likely reduces anomaly strength and coherence in the 3D volume.

Practical alternative: For cache hunting, a simple $22 bottle probe (available on Amazon) is a far more reliable tool for locating small to large caches buried in the ground.

A2 Testing Finding Voids Under Concrete

Using the GroundTech A2 in 3D Scanner mode, sub-slab voids were detected reliably and with high interpretive confidence. On the 3D heat maps, the anomalies presented as coherent, high-contrast volumes with sharp lateral boundaries and repeatable responses across adjacent survey lines—signatures consistent with volumetric discontinuities beneath concrete.

Conclusion: The A2 appears well-suited for locating tunnels, abandoned wells (empty or water-filled), septic tanks (empty or full), and larger conduits/utilities, where the contrast between the host material and an air- or fluid-filled cavity produces a distinct, easily interpretable response.

Next Set of Tests (For another article): Given its demonstrated effectiveness in detecting subsurface voids, I plan to further evaluate whether this technology can also differentiate Native American midden sites. As some of you may know, I work with an archaeology firm specializing in cultural resource management (CRM). If the system can reliably identify midden deposits, it could offer a non-invasive and efficient method for locating and delineating such sites during survey and pre-construction assessments.

Testing the A2 Groundtech Metal Detector Function

The A2 Metal Detecting Coils (Three Sizes & When To Use Them)

The A2 series supports PiD-series coils; official A2 kits commonly include PiD25 and PiD30, and GroundTech documentation also shows a PiD35 option in the family. Names reflect size class (≈ 25/30/35 cm).

• PiD25 (smallest): Highest sensitivity to small conductors; best separation in trashy or rocky ground; tight pinpointing.
  
• PiD30 (mid): Balanced choice for mixed sites; good general-purpose depth with manageable footprint.
  
• PiD35 (largest): Maximizes depth and ground coverage on medium-to-large targets (caches, relic clusters); expect broader footprints and less finesse in dense trash.
  

Testing the Groundtech A2 with the PiD30 (mid) General-Purpose Coil

Groundtech A2 Field Performance Evaluation

My detecting partner, an experienced relic hunter highly proficient with the Bounty Hunter Tracker IV, conducted an initial field test of the Groundtech A2 at a local park. Using a controlled set of metallic targets—including keyfob and small non-ferrous items—he observed that the A2 failed to register several targets that his Bounty Hunter detects easily. Based on his report, I suspected possible user error or incorrect settings and decided to replicate and expand the test under controlled conditions.

During a second controlled field evaluation of the Groundtech A2, we buried a coin cache composed of 100 U.S. quarters (rolled in paper, sealed in a small box, and enclosed within a nylon bag) at an approximate depth of 12 inches (≈30 cm) in a freshly tilled field. Each of the three coils — PiD25, PiD30, and Pi30 — was systematically tested over the target and sweep speeds. Despite trying all three coils, no detectable signal was produced. This result was highly unexpected given the size, density, and metallic composition of the target, which should fall well within the detection capabilities of both pulse induction (PI) and high-end VLF systems. The A2’s inability to register a signal raised serious concerns regarding its detection capabilities.

Controlled test-garden trials were subsequently conducted to quantify the detector’s true performance envelope and verify the operational integrity of its detection circuitry.

Controlled Test Garden Comparison

Testing was conducted in my backyard test garden, which features a PVC tube set one foot deep into the ground. A series of wooden rulers with targets securely attached(glued) at measured depth intervals can be lowered into the tube, allowing for repeatable and controlled testing conditions. The Groundtech A2 (mid-size coil) was directly compared with the following detectors:

• Minelab Manticore equipped with the M9 coil
• Nokta Legend fitted with the LG24 coil
• Bounty Hunter Tracker IV as a baseline reference

All detectors were operated using default or recommended park/general stock modes with sensitivity cranked to the highest, with identical sweep speeds and target separations to ensure consistency.

NOTE: For this test, I maintained a consistent setup and operated at the highest sensitivity setting. However, it’s important to note that when metal detecting in general, running at maximum sensitivity isn’t the best approach, as it can introduce instability and false signals depending on ground conditions.

Observations and Results Testing the Metal Detecting Feature

Across multiple controlled tests, the Groundtech A2 consistently failed to detect both small metallic targets (e.g., costume jewelry, key fob) and larger metallic masses (e.g., buried coin cache at 12″). Target acquisition lacked a repeatable tone response and exhibited signal instability.

In contrast, the Minelab Manticore and Nokta Legend detected all test items with clear, repeatable signals. Even the entry-level Bounty Hunter Tracker IV—a basic analog detector costing a fraction of the A2—demonstrated superior sensitivity and stability.

Under every test condition, the Groundtech A2 underperformed across sensitivity, target consistency, and depth response metrics. Based on these findings, the unit does not meet expected performance standards for relic or coin detection compared to detectors of similar or significantly lower cost.

GroundTech A2 — Ergonomics & Compactness (Technical Notes)

Based on field use alongside owning 15 other metal detectors and testing various ground-scanning devices, the A2’s human-factors profile is mixed. I frequently hike into remote sites, so I prioritize systems that are compact, light, and quick to deploy; the A2 meets those transport requirements well, but its on-body ergonomics constrain longer, precise transects.

From an ergonomics standpoint, the fixed-length shaft provides no anthropometric adjustment for taller operators. This forces a lower hand position and mild forward trunk lean, increasing wrist pronation and the moment arm at the shoulder over time. The absence of an arm cuff reduces forearm stabilization, which raises torsional load at the wrist and introduces micro-sway during passes—both of which can degrade line fidelity and height control in 3D scans.

Where the A2 excels is in packability. The unit is lightweight, folds quickly, and has a small stow volume that fits easily in a daypack or can be hand-carried on approaches. This compact form factor is important where weight and bulk are limiting factors.

Excels in Packability, Folds Down & Light

Conclusion: In practice, the A2’s form factor is well-suited to short surveys, spot checks, and scenarios where rapid mobility is critical. For taller users or extended grid work, a shaft extension (if/when available), an aftermarket arm support, or a simple shoulder sling can materially reduce fatigue and improve path stability and elevation consistency across lines.

Other Items to Consider

Note: The standard A2 package lists PiD25 + PiD30 plus the MFS-3 sensor; A2-GEO adds resistivity hardware (probes/cables). PiD35 availability can vary by bundle/region as an accessory. Always verify your kit contents.

Final Assessment: Who the Groundtech A2 Is (and Isn’t) For

The Groundtech A2 occupies a niche space between metal detection and geophysical surveying. Its integrated 3D ground-imaging capabilities and G-Portal app interface make it well-suited for users focused on void detection, structural mapping, and large anomaly reconnaissance—particularly in construction assessment, archaeological mapping, or locating underground utilities, septic tanks, wells, and tunnels. When used for these applications, the A2 provides repeatable, interpretable 3D data and performs reliably on large, high-contrast subsurface features.

However, for metal detection and cache hunting, the A2’s performance falls well below expectations. Despite its high cost and advertised PI technology, it lacks the sensitivity and target stability required for detecting coins, jewelry, or small to medium metallic caches. Even basic entry-level detectors such as the Bounty Hunter Tracker IV outperformed it in side-by-side field and test-garden comparisons.

In short, the Groundtech A2 is best viewed as a geophysical survey instrument rather than a detectorist’s field tool. It is appropriate for professionals needing to visualize large voids or subsurface anomalies, but it is not recommended for relic, coin, or cache detection. Those seeking reliable target acquisition for metallic objects—especially in variable soils—will achieve far better results with a dedicated VLF or PI metal detector at a fraction of the price.