In this mode, the device starts/ends trips based on accelerometer movement. 

• Accelerometer wakes the unit
  • By default, a wake filter is applied. The filter only starts a trip when it has seen 1 second’s worth of above-threshold movement in a 4 second period, or repeated short movements over several 4 second periods. Disabling the filter results in any accelerometer movement above the Wakeup Threshold (in Accelerometer Settings section of System Parameters) waking the unit.

• Unit immediately determines it is moving – this is the same as entering a trip.
• Once moving, the accelerometer no longer wakes the unit
• It wakes every three minutes on a timer, and does two things:
  • Asks the accelerometer if there was any movement in the last 3 minutes
  • If it is time to log a position, it gets a fix and records it

• Once the accelerometer claims there has been no movement for a while, (default is 5 mins - Movement End Time parameter), the device declares movement has stopped.

Periodic tracking mode is used to get position update on an interval (i.e. once daily) for greater battery life. When the device is set to "periodic only", it disables movement tracking and can give updates on an interval. There are two types of 'interval':

1. By default, if we set the Heartbeat Interval to 12hrs, the device will simply heartbeat initially when powered on, then every 12hrs after this
2. We can configure Scheduled Uploads to have the heartbeats occur at specific times (i.e. 9am and 3pm)