Compass Reading near North Pole

[Bolek Mellerowicz]

How does the geographic location e.g. near the Equator vs closer to North Pole affect the the heading readings (compass reading) of the UM7 sensor? Specifically I need to use this sensor up North in Summit, Greenland to measure the angular position as a regular compass would.

I am afraid that because the horizontal intensity is about three times less the UM7’s compass reading may not be reliable Is there a min. Horizontal Intensity the sensor requires to function (assuming calibraton and no hard iron distortions)?

NOAA has a magnetic field calculator see link below and I used it to compare the magnetic fields in Los Angeles vs Summit, Greenland.

http://www.ngdc.noaa.gov/geomag-web/#igrfwmm

Greenland:
Declination = -28 deg
Inclination = 81.1 deg
Horizontal Intensity = 8400 nT
North Comp. = 7400 nT
East Comp. -3990 nT
Vertical Comp 54000 nT
Total field = 54700 nT

Los Angeles:
Declination = 13 deg
Inclination = 58 deg
Horizontal Intensity = 24300 nT
North Comp. = 23800 nT
East Comp. 5100 nT
Vertical Comp 40100 nT
Total field = 46900 nT

Thank you,

Bolek

[Michael]

Hi Bolek,
This is a very interesting question I have had similar thoughts about using the sensor at the equator, but thats another story.

To be safe I think you should calibrate your unit in the local magnetic surroundings, and the sensor should operate as specified.
Are you able to perform Calibration on site, or are these being deployed from a test platform, and delivered to the area you mentioned?

However the UM7’s only limitation is the sensor itself, its sensitivity is ±4800 uT at full scale range.
so this gives the sensor about (9600 uT/ 2^14 bits) = apx 585.98 nT resolution.

However the figures you have posted look within these values, so I don’t think this would be an issue.

Regards,
Michael Malloy

[Author]

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