GPS
One of my research topic is about relativistic positioning system.
See papers:
[1] S.Carloni, L.Fatibene, M.Ferraris, R.G. McLenaghan, P.Pinto,
Discrete Relativistic Positioning Systems; arXiv:1805.04741 [gr-qc]
[2] S.Carloni, L.Fatibene, M.Ferraris, R.G.McLenaghan, A.Orizzonte,
Relativistic GPS in 3-dimensions
Relativistic GPS in 3-dimensions
The maple worksheets can be found here.