The goal of dopcalc is to forecast or hindcast GPS satellite constellations and associated positioning precision metrics for arbitrary locations. Use cases include GPS mission planning, i.e. determining times of good GPS coverage at a survey location, or post-hoc precision estimation for GPS data that lacks signal quality information.

The initially targeted use-case is focussed on seabirds at sea, so horizon shading by terrain or the built environment is currently not considered.

Calculations are based on GPS almanac data. Optional automatic downloads of the required almanac files from the US Coast Guard Navigation Center when necessary are part of the planned functionality.

The R package draws on previous work by others, in particular [Master's thesis]

This is a basic example which shows you how to solve a common problem:

## basic example code