How does traccar server determine if a device has stopped?
Traccar creates deviceStopped event when previous position has speed more than zero and current position has speed about zero.
What is the threshold? What is considered more than zero and what is considered about zero?
Threshold is 0.01 knots. It can be configured using "event.motion.speedThreshold" parameter.
Is the speed in positions table in knots? If not what unit is it?
Yes, it is in knots.
Traccar server sends a deviceStopped event via socket whenever a device stops.
But how is it done? I basically need to know this because I am planning to set my gps tracker to send device updates only 4 times a day to save battery. This deviceStopped event is very essential to my implementation of the app I am creating, so I want to know if traccar server can still effectively report device stop event having only 4 position reports per day.