The Oyster3 operates in a similar way to its predecessor model, the Oyster 2.
Default Parameters - Out of the box, the device will:
- Heartbeat every 12 hours
- Log a position every 2 min, and upload every 30 min while in trip.
The Sony GPS module used in the Oyster3 has two operation modes
- Performance: The default mode of operation. The GPS works slightly harder to get a fix, scanning for a bit longer. This leads to the best performance. In good signal, power consumption is very similar to the low power mode.
- Low Power: Consumes marginally less battery compared to the performance mode. More power efficient in poor signal conditions (but it's likely we'd want to use performance mode to increase the chances of getting a fix anyway)
The Oyster3 revolves around the concept of a 'trip' for tracking. When the device detects it is in a trip, the update rate is increased.
In this mode, the device starts/ends trips based on GPS movement. There is filtering in place so that small movements do not start trips. E.g. if you move your car from one side of the street to the other, a trip will not start. But if you drive a block away, it will.
This default mode is ideal for most applications where we are looking to record trips/activity where some distance is covered (typically assets that are driven or towed)
- The device waits in a low power sleep state for accelerometer activity.
- Once woken by accelerometer movement, it checks the GPS for movement periodically
- If the device is being repeatedly woken up by accelerometer movement, but there is no GPS movement, it wakes up on a timer every few minutes instead (to save battery)
- If the GPS shows movement over the start threshold (250m by default), a trip is started.
- Once in trip, the accelerometer is turned off
- It wakes up every few minutes and gets a fix
- It checks the trip is still in progress by looking at the fix
- When the fixes suggest movement has stopped, it ends the trip
- If GPS signal is lost for some time the trip ends also
Trips can be started based purely on accelerometer movement (vibration). Applications include
- Tracking run hours on a stationary piece of equipment. When it is turned on there will be accelerometer activity and run hours can be accumulated
- Tracking very small trips (i.e. a piece of equipment in a yard)
- Instant alerts on movement for theft prevention (GPS tracking mode will take a bit of time to start a trip and upload)
- 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 two minutes on a timer, and does two things:
- Asks the accelerometer if there was any movement in the last 2 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.
- The device will also wait until the speed reported by the GPS has dropped to 0, to prevent movement ending when the movement is very steady and constant – e.g. a train where acceleration is minimal
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 trip tracking and can give updates on an interval. vThere are two types of 'interval':
- By default, if we set the Heartbeat Interval to 12hrs, the device will simply heartbeat initially when powered on, then every 12hrs after this
- We can configure Scheduled Uploads to have the heartbeats occur at specific times (i.e. 9am and 3pm)