Groundtech GR-4 3D Ground Scanner

The Groundtech GR-4 is a standalone 3D ground scanner for treasure hunters, relic hunters and anyone who surveys ground for buried objects and wants results in the field without a phone or tablet. Its MFS-2 dual sensor gradiometer reads the ground, a high-resolution color display shows the scan as you work, and Groundtech gives a 3D scanning depth of up to 15 meters (49 feet), depending on the target's size and the soil structure. Scans can also go to Groundtech's G-Portal app on Android and iOS for 3D and 4D analysis and reports.

What is in the box with the Groundtech GR-4

Groundtech's standard contents for the GR-4

• Groundtech GR-4 main unit with built-in color display
• MFS-2 Dual Sensor module
• Charging adapter
• Carrying bag
• User manual

How the Groundtech GR-4 scans

Groundtech says the GR-4's 3D Ground Scanning System detects, measures and locates buried metals, magnetic objects, graves, rooms and cavities such as tunnels. The MFS-2 dual sensor gradiometer has a measurement range of plus or minus 2000 microtesla and works with a 480 MHz processor and a 12-bit A/D converter, and Groundtech says the results graphically show magnetic metals (iron or steel) and non-magnetic metals (gold, silver or copper). Groundtech gives a 3D scanning depth of up to 15 meters (49 feet), with the reach depending on the target's size, the soil structure and the scanning function. We would expect small objects to read at much shallower depths than the headline figure.

Three scanning modes

• 3D Ground Scanning: a systematic survey of an area that maps what the sensors read in three dimensions.
• Live Scanning: Groundtech says it graphically shows underground objects without tying you to a fixed search pattern.
• Pinpointer: helps locate the exact position of an object before you dig.

Live Scanning gives immediate feedback as you walk, and we like it for a first look at a site. A quick live response does not replace a properly run grid scan when you need a detailed analysis.

Built-in screen and the G-Portal app

Settings, scanning modes and results appear on the GR-4's high-resolution color display, so the scanner works on its own in the field, and the GR-4 stores up to ten 3D scans on the device. Over Bluetooth 5 (LE), the G-Portal (Groundtech Portal) app for Android and iOS saves your scan data, lets you examine 3D and 4D analyses in more detail and generates survey reports. Groundtech lists 11 languages on the device and 25 languages in the mobile app.

Design and battery

Groundtech builds the GR-4 with a foldable modular body, an adjustable grip angle and a removable sensor module, and calls it a leader in its class for portability and field adaptability. Power comes from a 7.2 V, 3.2 Ah rechargeable lithium-ion battery that Groundtech rates at up to 10 hours of 3D scanning, charged over USB Type-C with a 25 W charging adapter. The GR-4 weighs 760 grams (1.7 pounds), and Groundtech gives an operating temperature range of minus 10 to 60 °C (14 to 140 °F).

For a pulse induction metal detector in the same body, Groundtech makes the Groundtech GR-4 DUAL.

Who the Groundtech GR-4 suits

The GR-4 suits buyers who want a dedicated 3D magnetic ground scanner. It is a more developed scanning platform, with its own screen and interface plus Groundtech's G-Portal analysis software, and it is made for investigating anomalies below the surface rather than hunting ordinary coins. Its strongest point is magnetic scanning combined with graphical analysis in G-Portal.

What magnetic scanning can tell you

Picture a search of a historic property for buried ferrous objects. The GR-4 records variations in the magnetic field, and its 3D scanning system lets you analyze them as a graphic. A scan shows you where to look, not what an object is worth.

Groundtech GR-4 or GR-3

We would pick the GR-4 over the Groundtech GR-3 for the newer interface and the G-Portal software. We would not claim that it automatically finds every target deeper or more accurately.

One mistake to avoid with the GR-4

The biggest mistake is expecting a metal detector in the standard GR-4. The integrated pulse induction metal detector belongs to the GR-4 DUAL; the GR-4 is a 3D scanner, and that is the most important difference between the two.

Permission and protected sites

We would get the landowner's permission before any survey and check the laws that protect historic sites, archaeological sites and burials where you plan to scan. A Groundtech scanner can show where something is different underground; it does not tell you whether you may dig there.

Groundtech GR-4 specifications

Groundtech covers the GR-4 with a 2-year warranty.

Every GR-4 model we carry is in our Groundtech GR-4 collection, and our Groundtech buyer's guide compares the full Groundtech range.