Groundtech GR-3 3D Ground Scanner

The Groundtech GR-3 is a handheld 3D ground scanner for treasure hunters and relic hunters who want to start 3D ground scanning with a light, simple wand. It weighs 600 grams (1.3 pounds), has no cables or external battery, and sends its scan to the Conrad GR-3 app on an Android or iOS phone or tablet in real time. Groundtech gives a scanning depth of up to 7 meters (23 feet), depending on the target's size and the soil structure.

What is in the box with the Groundtech GR-3

Groundtech's standard contents for the GR-3

• Groundtech GR-3 main unit
• 25 W charging adapter and USB-C charging cable
• Carrying case
• User manual

How the Groundtech GR-3 scans

Groundtech builds the GR-3 on a single CN-D sensor and the GR-3 PLUS on a dual CN-D sensor; both work with a 240 MHz processor and a 12-bit A/D converter. The scan data appears in real time on your phone or tablet over Bluetooth 4.2 BLE, and Groundtech says the software graphically displays magnetic metals (iron or steel) and non-magnetic metals (gold, silver or copper), as well as cavities such as graves, rooms and tunnels. Groundtech gives up to 7 meters (23 feet) for the GR-3 and says it can be used on sandy, rocky or clay soil. Groundtech's maximum depth figure depends on the target's size and the soil structure, so we would expect small objects to read at much shallower depths than the headline figure.

Four scanning modes

• Auto: automatic 3D ground scanning.
• Manual: manual 3D ground scanning.
• Live Scan: quick graphical scanning without a fixed search pattern.
• Pinpointer: helps locate the exact position of an object before you dig.

Scanning technique on the GR-3

Consistent scanning matters more on the GR-3 than anything else. Walk every line of the grid at the same pace, in the scanning pattern the Groundtech manual sets out. If you walk one line slowly and the next one quickly, the data gets hard to interpret, and a real anomaly can look like noise. We would learn that pattern before the first real survey.

App, battery and size

Scans save to your mobile device so you can review them after the survey, and Groundtech lists the GR-3 app in 23 languages. The 3.7 V, 3.2 Ah rechargeable lithium-ion battery is internal and runs up to 10 hours, according to Groundtech, and charges over USB Type-C with a 25 W charging adapter. The GR-3 measures 810 x 70 x 70 mm (31.9 x 2.8 x 2.8 inches). Groundtech gives an operating temperature range of minus 10 to 60 °C (14 to 140 °F).

For up to 15 meters (49 feet) of 3D scanning depth with a dual sensor in the same body, Groundtech makes the Groundtech GR-3 PLUS.

Who the Groundtech GR-3 suits

The GR-3 suits buyers who specifically want to investigate magnetic ground anomalies with a portable 3D scanner. Instead of a conventional search coil, it uses a magnetic sensor to measure changes in the ground's magnetic field. In our experience that makes it interesting for possible buried structures, large ferrous objects and unusual ground conditions. Its strongest point is portable magnetic scanning with graphical analysis.

What a GR-3 scan shows, and what it does not

Picture an older property where a large iron object may be buried. You walk a systematic grid, the GR-3 records magnetic measurements, and the app turns them into a graphic of the area. That graphic can point you to a spot worth investigating further. It is not a photograph of the buried object.

Your phone or tablet is the screen

The GR-3 shows its data in the Conrad GR-3 app, so you read your scans on a device you already know, which we like. Check that your phone or tablet is compatible with the app before you buy.

One mistake to avoid with the GR-3

The biggest mistake is reading every magnetic anomaly as buried treasure. An anomaly shows you where the ground reads differently and is worth a closer look, and a consistent grid scan is what makes that reading worth trusting.

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-3 specifications

Groundtech covers the GR-3 with a 2-year warranty.

Both GR-3 models are in our Groundtech GR-3 collection, and our Groundtech buyer's guide compares the full Groundtech range.