Logger Export
FGA Logger stores magnetic field and GPS data on a removable SD card as comma-separated value (CSV) files. Each row corresponds to a single sample from the connected sensors, along with precise time and location information. The files can be opened with spreadsheet software (Excel, LibreOffice), scripting languages (Python, MATLAB) or specialized magnetic data tools (Surfer, PolarWave DATA).
Retrieving Data
- Stop logging. Press the logger's start/stop button to end the recording session. The SD logging LED will stop flashing when logging is complete.
- Connect via USB or remove the SD card. You can either attach the logger to your computer using the USB-C port, or eject the SD card and insert it into a card reader.
- Copy the CSV file. Navigate to the SD card's storage directory and copy the
.csvfile(s) to your computer for analysis.
CSV File Format
Each CSV file includes a header row followed by one data line per sample.
| Column | Description |
|---|---|
| Timestamp_ms | Timestamp in milliseconds — indicates the exact time each data row was recorded |
| B1x_nT | Magnetic field component along the X-axis from sensor 1, in nanoteslas |
| B1y_nT | Magnetic field component along the Y-axis from sensor 1, in nanoteslas |
| B1z_nT | Magnetic field component along the Z-axis from sensor 1, in nanoteslas |
| B1v_nT | Total magnetic field magnitude from sensor 1 (vector magnitude of B1x, B1y and B1z) |
| B2x_nT | Magnetic field component along the X-axis from sensor 2, in nanoteslas |
| B2y_nT | Magnetic field component along the Y-axis from sensor 2, in nanoteslas |
| B2z_nT | Magnetic field component along the Z-axis from sensor 2, in nanoteslas |
| B2v_nT | Total magnetic field magnitude from sensor 2 |
| Lat_deg | Latitude in decimal degrees |
| Lon_deg | Longitude in decimal degrees |
| Alt_m | Altitude above sea level, in metres |
| SIV | Satellites In View — number of satellites the GPS receiver can detect |
| Fix | GPS fix status (0 = no fix, 1 = valid fix) |
| HDOP_m | Horizontal Dilution of Precision — indicates GPS positional accuracy; lower values are better |
Example Data
A header row followed by data samples:
Timestamp_ms,B1x_nT,B1y_nT,B1z_nT,B1v_nT,B2x_nT,B2y_nT,B2z_nT,B2v_nT,Lat_deg,Lon_deg,Alt_m,SIV,Fix,HDOP_m
66691,3.59,-0.26,1.04,3.75,68273.24,68275.54,68272.28,118253.50,46.2485761,13.5737527,300.70,7,1,2.65
66791,3.05,1.97,-1.31,3.86,68274.20,68271.66,68267.43,118249.00,46.2485763,13.5737528,300.685,7,1,2.65
66891,2.71,3.35,4.09,5.94,68271.02,68267.31,68269.26,118245.72,46.2485766,13.5737532,300.646,7,1,2.65
Using the Data
- Excel / LibreOffice — open the CSV file directly to view and chart the magnetic and GPS data
- Python / MATLAB — use built-in CSV readers (e.g.
pandas.read_csv) to load the file for custom analysis - GIS software — import the data to map magnetic anomalies over geographic coordinates
- PolarWave DATA™ — upload the CSV for automated visualization and advanced processing
Tips and Best Practices
- Always ensure the SD card is formatted as FAT32 before logging
- Check the SD card logging LED — blinking indicates logging is in progress; a solid light may indicate an error
- If a logging error occurs, verify that the SD card is properly inserted or try another card
- Keep the GPS antenna unobstructed to maintain a good satellite fix and accurate position data
With this knowledge you can confidently export, interpret and analyse your FGA Logger data.