Harry's GPS Suite Forum

When I use iPhone 14's internal GPS, the trigger works fine and starts the timer automatically at around the start line.

However, if I use DUAL XGPS 160, the trigger kicks in very often (every 20 to 30 seconds) and starts the timer even when I'm still waiting at the grid that is far away from the start line. Other than the trigger issue, GPS data looks very accurate so I don't think this is a GPS issue.

Have you changed the Expert Setting on "trigger at low speeds"? By default it is off to workaround false starts from triggers detected accidentally. This occurs because GPS data is noisy. Depending on signal strength and atmospheric disturbances, the position jumps around in a certain area around your real position. In case these jumps are interpreted as crossing a trigger, you get these false starts. In case "trigger at low speeds" is OFF, LapTimer will ignore any trigger as long as you do not drive something like 5 km/h or more. The probability you get a false start from a 10 Hz devices is 10 times that of one with 1 Hz.

I don't remember if I ever changed the "trigger at low speeds" setting but "Allow Low Speeds" is set to on.
So I should set "Allow Low Speeds" to off to avoid the false start, then?

Yes.