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FGM-3h Geomagnetic Fluxgate magnetometer UK data with Arduino


In summer 2013 I purchased a fluxgate magnetometer from Speake & Co for monitoring the earth's geomagnetic field. Their FGM-3h sensor is extremely sensitive and can measure the 100nT diurnal variation in the Earth's magnetic field.

The sensor is buried approx 60cm deep in the ground in my back garden near Southampton, UK. This is to isolate it from daily temperature variations which would otherwise swamp the reading we are trying to make.

The sensor is connected via a long shielded cable to an Arduino Mega 2560 inside the house. Connected to the Arduino Mega is a circuit of my own devising.

Source code example sketch

Here is a sample sketch for reading the FGM-3h magnetometer that simply counts the pulses from the FGM-3h and sends the result down the serial port.

I'm using a much more complex program in my observatory which includes an internet connection and a GPS for good timing.

There are a number of limitations with the system at present

Select date range for geomagnetic field data to display:  

Current data range: 5 days.
Last update: 2019-02-23 05:53:39
Data averaged over 10 minute intervals;
RED = Sensor Temperature, C
BLUE = Field, nT