What is Geo Fence Timing
Geofence timing allows a virtual timing point to be added to a course. This allows for timing points without the need for someone to be in attendance. This is great for remote timing points such as mountain tops.
How Does a geo fence work?
A longitude /latitude coordinate (timing point) is added to the tracking map. When the geofence radius around the coordinate is reached then the time is recorded, as the tracker gets closer to coordinate the time is updated to reflect the most accurate time. How big the radius around the coordinate needs to be considered carefully. A large radius could allow a competitor to show they have visited a checkpoint without actually doing so. A small radius around the coordinate can result in a competitor visiting a checkpoint but it not being recorded.
When setting up the geo fence around the coordinate we need to take a few things into account such as;
The speed the tracker is travelling
The terrain and physical area (forests and valleys can result in tracker not getting a location fix for example)
The frequency the tracker records its location.
Position of tracker being carried (should have good line of sight to the sky)
In the ideal world the tracker would record its location every second, this is possible but when the tracker is constantly sending reports it very quickly runs down the battery.
Intervals on the Tracker
For a trackers battery on a tracker to last 24 hours the interval needs to be set at 60 seconds. This means the tracker will record and send its location every minute. If the geofence radius was set too small an area the tracker will not record that the coordinate was visited.
If a runners pace was 10kph they would travel at 167 meters every minute, so the minimum the radius would need to be is 84 meters (to ensure that a track point is recorded in the geofence), this would also not allow for any errors from the tracker i.e not getting a location fix.
If a cyclist pace was 40kph they would travel 667 meters every minute, so the minimum the radius would need to be is 333 meters (to ensure that a track point is recorded in the geofence), this would also not allow for any errors from the tracker i.e not getting a location fix.