Investigations into the relationship between GPSDOP and unit-vector tetrahedron volume

Dilution of Precision (DOP) is an important factor which decides the accuracy of a satellite-based navigation system. There is a globally prevailing statement that DOP depends on the tetrahedron formed due to navigation satellites. However, the definition of tetrahedron volume and its relation to DOP is found ambiguous in the open literature. A review of the existing definitions is made and an attempt is done to identify the proper relation. Data collected from DL-4 plus GPS receiver kept at Osmania University, Hyderabad city is utilised for this purpose. It is found that the unit-vector tetrahedron volume formed due to four satellites is found inversely proportional to the DOP, most of the time. But the relation is not true for all combinations of satellites.