ARTOA4-formula-overview.md

+## SATFIX estimated time of arrival
+
+For every soundsource where a SATFIX is available, the estimated time of arrival is calculated the following way:
+
+```math
+ETA = windowStartTime [s] - leapSeconds [s] + \frac{distance ~[km]}{soundspeed ~[km/s]} - floatWindowStart [s]
+```
+
+where
+
+```math
+windowStartTime [s] = soundsource.reftime - (float.phasereftime * floatSchedule)~modulo~24
+\newline
+floatWindowStart [s] = float.windowstart
+```
+
+## TOA calculation for soundsource during tracking algorithm
+
+```math
+TOA_{resulting (t, u)} = TOA_{measured} + Offset_{float} + Drift_{float (t)} - Offset_{soundsource} - Drift_{soundsource (u)}
+```
+
+where
+
+- $`Offset_{float}`$ is the offset of the float,
+- $`Drift_{float (t)}`$ is the drift of the float at timestamp t (since start of float),
+- $`Offset_{soundsource}`$ is the offset of the soundsource,
+- $`Drift_{soundsource (u)}`$ is the drift of the soundsource at timestamp u (since start of soundsource).