position fixing by means of a compass
If no GPS instrument (position fixing via satellites) is available or a hiker wants to avoid all unnecessary weight or if security considerations require alternative technology, special bearing compasses are the obvious solution:
All the abovementioned systems allow for a reading accuracy of up to 0.1 degrees or 0.1 gradian. By eliminating magnetic interference, by taking a bearing on at least three mapped out points and by extensive determination of mean values, instruments such as these can be used in the same way as simple theodolites. The angular distance between the magnetic and the geographic North Pole, called "magnetic variation", is to be determined by consulting current topographic maps.
- lensatic bearing compass
- prismatic bearing compass
- combinations of binoculars and compasses
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