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3-Axis Simple Aurora Monitor (SAM-III) Description and Specifications

The 3-axis Simple Aurora Monitor (SAM-III) magnetometer system is a sophisticated semi-professional geomagnetometer designed by Dirk Langenbach (hardware) and Karsten Hansky (software). 

The primary application of the SAM-III is in the sensing and study of geomagnetism, but it is possible to use the SAM-III in other applications requiring magnetic sensing.  The correspondences between geomagnetic storms, solar events and solar wind, aurora and radio propagation anomalies are well-known.  The SAM-III will be a useful instrument to radio astronomers, radio amateurs, aurora photographers and experimenters. 

Click here for a Geomagnetism Tutorial 

The original SAM and the newer SAM-III forms the basis for a magnetometer network in Europe.  We wish to expand this to a worldwide amateur geomagnetometer network, and our goal is to deploy the SAM or SAM-III on every continent.  The southern hemisphere is under-represented even in professional geomagnetometer chains and networks, so we are particularly interested in deploying the SAM-III in southern latitudes.  To become a member of the SAM network, internet access is required. 

Click here for SAM-III ordering information

The orginal sensors used with the SAM-III were model the FGM-3 fluxgate magnetometer sensor manufactured by Speake & Co Llanfapley. Click here for detailed information. These fluxgates sensors are no longer available and have been replaced by an equivalent model FG3+. The sensor signals are processed by a Microchip PIC16F877 microcontroller operating at 16 MHz and associated logic circuitry. Click here for Frequently Asked Questions (FAQ) associated with the SAM-III.

Sensor outputs, K-index and time and date are shown on a liquid crystal display.  Additional interface circuitry provides serial data, analog K-index and alarm outputs for external processing and display on a PC or voltmeter.  The processor can be set to provide a dry contact alarm relay closure when the K-index exceeds a predetermined value.  The alarm function is useful to aurora photographers and radio amateurs because it could indicate aurora picture and radio propagation opportunities.

The SAM-III may be operated in an autonomous (standalone) mode or it may be used with a PC for logging and viewing. 

The basic specifications for the SAM-III magnetometer system are

  • Range: Approximately 50000 nT

  • Resolution: 1 ~ 2 nT

  • Connection of 1, 2 or 3 sensors  

  • Microprocessor controlled, 16 MHz clock

  • Data displayed on backlit 4x20 LCD (STN yellow/green standard)

  • Measured data transmitted over EIA-232 serial interface as ASCII text

  • K-Index available on one analog output (adjustable 0 ...+5 V or -2.5 ...+2.5 V)

  • Real-time clock with backup battery

  • Form A relay output for K-index alarm (maximum contact rating 30 V dc or V ac-peak, 1.0 a dc or a ac-peak, in a combination not exceeding 20 w)

  • Opto-isolated input for detection of external voltage condition to deactivate measurements

  • Software setup and measurement logging via EIA-232 serial interface

  • Power: 12 V dc at 60-100 mA (depending on number of sensors connected)

  • Dimensions (optional enclosure): 165 mm x 125 mm x 76 mm

  • Temperature sensing capability

  •  Connectors:

  •  I/O: Pluggable terminal block, 8-pin

  • Sensor: Pluggable terminal block, 10-pin

  • EIA-232: DB-9M

  • dc power coaxial 2.1 mm x 5.5 mm, center +

  • Keyboard controls:

  • Command mode (F1)

  • Calibration mode (F2)

  • Software reset (F3)

  • Display backlight (F4)

  • Application software:





  • PC operating systems: Windows XP, 7, 8 and 10

The setup software used with the SAM-III allows the user to adjust the SAM-III onboard parameters for standalone operation.  When the SAM-III is connected to a PC running the included logging and viewing software, the software collects data from the SAM-III and provides additional downstream processing and archiving of magnetometer data.  The software also produces a graphics file that may be viewed locally by any graphics viewing program or transmitted by File Transfer Protocol (FTP) to a web server for viewing on the internet.

Click here to download the SAM-III construction manual and software setup manual and other information.

Logging and viewing software screenshot showing the effects of a coronal hole high-speed stream.Click on the image to go to real time data from our
Anchorage observatory

Because of the magnetometer sensor sensitivity to both temperature and man-made disturbances, it normally is installed at a remote location and buried in the ground. We are aware of sensor installations greater than 60 m from the SAM-III processor.  The documents above including the SAM-III Construction Manual provide information for siting the sensor and for constructing a sensor fixture. For information on calculating the burial depth in soil to reduce temperature variations, see Burial Depth of SAM-III Magnetometer Sensors.

The SAM-III consists of a main controller printed circuit board (PCB), keyboard PCB and Liquid Crystal Display (LCD) module and up to three sensors  The controller PCB is shown below.

Although the SAM-III includes viewing and logging software specifically designed for it, it can be used with other logging methods. When in standalone mode (not connected to a PC), SAM-III only displays the real time data and does not remember it. If a user needs to log data but does not wish to have SAM-III connected to a PC, the EIA-232 serial interface can be connected to a serial data recorder.

The SAM-III has been tested with the Acumen Instruments SDR2-CF serial data recorder, which uses a compact flash card to save the serial data. When set to a 1 Hz sampling rate (the fastest rate available), the SAM-III produces approximately 3.7 MB of ASCII text data per day or about 115 MB per month. Each data sample includes a time/date stamp and magnetic induction values followed by Carriage Return/Line Feed characters.

The SAM-III also has an analog output that can be used to display or record the K-index. The analog output can be adjusted for a range of 0 to +5 v or -2.5 to +2.5 v.

Some users have written custom application programs that use the EIA-232 serial port to collect data for analysis and display but we presently do not have any information on these applications.

Click here for real time display of the SAM-III running in our Anchorage observatory

Click here for SAM-III ordering information

Click here for some SAM data