Blog
Notes on finding direction
Longer pieces on the physics of the field, the history of the card, and the failure modes of the sensor in your pocket.
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History
Why the compass rose has 32 points
The rose was built by halving: cardinals, then ordinals, half-winds and quarter-winds. Where the names come from, and why it stopped at 32.
4 min
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Fundamentals
Magnetic declination, explained
True north and magnetic north are different directions, and the angle between them is why your map bearing and your compass disagree. How to correct it.
4 min
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Sensors
Why your phone compass drifts
A magnetometer measures a very weak field, so almost anything nearby wins. What causes drift, what calibration really does, and how to tell them apart.
4 min
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