User's Manual

Document MV0319P.N
© Xsens Technologies B.V.
MVN User Manual
105
Figure 62: Show magnetic disturbances
In Figure 62, the MT on the left hand shows a warning and is probably close to a wall or an iron object.
The rest of the circles are green which indicates that the magnetic field is suitable to perform a
calibration. The advice is to move to a different location in such way that the red circle becomes yellow
or (preferably) green.
When some circles are green and some are yellow or red, try to find a spot in the room or building where
the red circles disappear. When the red circles around the feet remain at all locations, you can step onto
an object to gain some distance from the floor (e.g. you can use the MVN suit case) and perform a
calibration. After the calibration you can then step on to the floor and work there for quite some time
before performance degrades. When all circles are red and remain red when walking around, the room
or building is not suitable for capturing with MVN. This is extremely rare. Try to use another location if
possible.
When a circle turns red for a short period; it indicates that the field is locally disturbed. The MVN Fusion
Engine offers a high grade of rejection against temporary disturbances and you can continue with
recording without worrying.
19.2.2 Magnetic Norm
Since MVN Studio 3.1.5, it has been possible to view the magnetic field norm in the graphs. This is
found in > Sensor data > Magnetic Field and is represented by the black line in the graph.
Magnetic norm facilitates the finding of a magnetically sound environment needed for calibrations and
preferred for measurements.
Note: Mag Field Norm is not an exported value. However it can be calculated as follows:
Mag Field Norm = squareroot (xˆ
2
+yˆ
2
+ zˆ
2
)
The following figures and explanations show how best to use the Magnetic Field Norm data in a practical
situation. The upper graph of both Figure 63 and Figure 64 is the head, and the lower graph is of the