Overview
Introduction
FG Sensors designs and manufactures fluxgate magnetometer sensors, magnetometer kits, and gradiometer systems for measuring weak magnetic fields. Products are used across a range of fields including geophysics, archaeology, metal detection, scientific research, and education.
FG Sensors systems are designed for field deployment and laboratory use, offering both standalone sensor modules and complete integrated systems with data logging, GPS, and software support.
Core Technology
FG Sensors products are based on fluxgate magnetometer technology. A fluxgate sensor uses a magnetically permeable core driven into saturation by an alternating current. Distortions in the resulting signal caused by an external magnetic field are detected and converted into a measurable output proportional to field strength.
Key characteristics of fluxgate technology:
- Detects static (DC) and low-frequency magnetic fields
- Sensitive to field strengths in the nanotesla (nT) to microtesla (µT) range
- No moving parts — solid-state operation
- Suitable for measuring Earth's magnetic field and anomalies within it
1-Axis Sensors
FG Sensors offers two types of 1-axis fluxgate sensors: a raw frequency-output sensor (FG-3+) and a fully calibrated sensor with direct field output (FG-3C).
FG-3+
The FG-3+ is the core sensing element used across many FG Sensors kits and systems.
| Parameter | Value |
|---|---|
| Type | 1-axis fluxgate magnetometer |
| Measurement range | ±50 µT |
| Output | Square wave frequency proportional to field |
| Supply voltage | 5V DC |
| Current draw | ~12 mA |
| Bandwidth | DC to ~20 kHz |
The FG-3+ outputs a square wave whose frequency varies in proportion to the measured magnetic field, connecting directly to a microcontroller timer input without an ADC. Commonly used in DIY magnetometers, gradiometers, and custom electronics systems.
FG-3C
The FG-3C is a fully calibrated and linearized 1-axis fluxgate magnetometer based on the FG-3+ sensing core. It adds digital processing and factory calibration, outputting magnetic field values directly in nanotesla (nT).
| Parameter | Value |
|---|---|
| Type | 1-axis fluxgate magnetometer |
| Measurement range | −60 µT to +60 µT |
| Supply voltage | 5V ±0.25V |
| Current draw | ~35 mA |
| Refresh rate | 100 ms (10 Hz default) |
The FG-3C supports three output interfaces:
- UART digital output — magnetic field value in nT at 115200 bps
- Analog voltage output — 0.5 V at +60 µT, 3.0 V at −60 µT
- Frequency / PWM output — 5V square wave, 30 kHz at +60 µT, 130 kHz at −60 µT
The FG-3C is temperature compensated and factory characterized, removing the need for external calibration. The frequency output maintains compatibility with existing FG-3+ installations.
Product Categories
Gradiometer Kits
Gradiometer kits use two matched FG-3+ sensors separated by a fixed distance to measure the gradient of the magnetic field rather than its absolute value.
- Two factory-matched sensors
- Measures the difference in field between two points
- Cancels out uniform background fields (e.g. Earth's field, electrical interference)
- Increases sensitivity to local magnetic anomalies
- Used for: metal detection, archaeological surveys, geophysical prospecting
Professional 3-Axis Magnetometer Kits
Professional systems integrate 3-axis sensors with data acquisition and logging hardware.
- 3-axis magnetic field measurement (X, Y, Z)
- Integrated GPS for georeferenced surveys
- SD card data logging
- USB and UART data output
- Compatible with FGA Logger software
- Used for: scientific field surveys, magnetic anomaly mapping, research
Typical Applications
| Application | Description |
|---|---|
| Geophysical surveying | Mapping subsurface magnetic anomalies for geological analysis |
| Metal detection | Locating buried metallic objects using gradient measurements |
| Archaeology | Non-invasive detection of buried structures and artefacts |
| Scientific research | Laboratory and field magnetic field studies |
| Magnetic anomaly detection | Identifying deviations from the background geomagnetic field |
| Educational experiments | Teaching magnetic field measurement and sensor principles |
| Aurora and space weather monitoring | Detecting geomagnetic field variations associated with auroras and space weather events |
Aurora Detection and Space Weather Monitoring
Fluxgate magnetometers can detect small variations in the Earth's magnetic field caused by geomagnetic activity. These magnetic disturbances are associated with auroras and space weather events such as geomagnetic storms.
FG Sensors systems — including FG-3+, FG-3C, and FG-4 sensors combined with data loggers — can be used for long-term continuous geomagnetic monitoring. The low noise floor and DC response of fluxgate sensors make them suitable for detecting slow field variations characteristic of geomagnetic disturbances.
Typical uses:
- aurora detection stations
- space weather monitoring networks
- geomagnetic research
- educational observatories
Documentation Structure
This documentation covers the full range of FG Sensors products, hardware components, and software tools.
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Introduction — Product overview, sensor technology, and documentation guide.
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Products
- Sensors — Documentation for individual magnetometer sensors including FG-3+, FG-3C, FG-4, and paired FG-3+ sensors. Includes specifications, pinouts, output formats, and integration notes.
- Boards — Documentation for hardware interface boards including the Converter Circuit Board and MAG-BOARD.
- Loggers — Documentation for magnetic field data logging systems such as the FGA Logger.
- Kits & Systems — Setup guides for complete measurement systems including the DIY Gradiometer Kit, Professional 3-Axis Magnetometer Kit, and DroneRover Enterprise UAV magnetometer system.
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Integration — Hardware wiring diagrams and software integration examples for microcontrollers, embedded systems, UART communication, and data acquisition.
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Data Analysis — Exporting and processing recorded magnetic data using tools such as FGA Logger export utilities, Google Earth mapping, and Surfer software.
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Maintenance — Calibration procedures, firmware updates, troubleshooting, and best practices for maintaining sensor accuracy and system stability.
Next Steps
If you are new to FG Sensors products, start with the Product Selector to identify the correct sensor or kit for your application. The Product Selector provides a comparison of all available systems based on axis count, output type, and intended use case.