The Oyster3 has 3 tracking modes (Oyster3- Tracking Modes).
- GPS Movement Based Tracking
- Accelerometer (Jostle) Based Movement Tracking
- Periodic Tracking
For modes 1 and 2 - the accelerometer is used to wake the device.
For GPS Movement Trips the accelerometer will wake the device on some slight movement, then the device checks the GPS to see if significant movement has occurred and whether to start a trip.
In Jostle Mode the trip is started immediately after some accelerometer activity.
Generally the defaults work well but we can adjust the accelerometer thresholds (intensity and duration of movement) required to wake the device or begin a trip.
Default settings shown below.
Wakeup Threshold and Wakeup Count determine what level of activity will wake the device before it will then start checking against other filtering before deciding if a trip should start.
GPS Tracking Mode Wake Filter
In regular GPS trip tracking mode, the device then checks for a legitimate trip start using the GPS. Two mechanisms are available to prevent small vibrations during asset handling from causing an excessive number of nuisance wake-ups, for instance during the loading of a trailer.
- After each wake up, the device sleeps for a short, fixed, time. This limits the maximum rate of wake-ups, and gives the asset an opportunity to get underway if it really is beginning a trip. In this case, the first GPS fix will be more likely to detect movement.
- If too many jostle event are detected without any real movement being detected, the device will temporarily ignore the accelerometer, and sleep for a longer time before checking the GPS for movement. This provides a stricter limit on the maximum rate of wake ups.
- The Wake-up Delay is the minimum time spent sleeping after jostling has woken the Device. It can be set to zero if low latency is required, but in most cases is best set between 10 and 60 seconds, to give the asset a chance to start moving before the GPS is activated.
- The No Movement Limit is the maximum number of nuisance wake-ups to tolerate before switching to a longer sleep time. Each time the device wakes up, sleeps the Wake-up Delay, and then finds no GPS movement, it increments a counter. When the counter reaches the No Movement Limit, the device starts to sleep the No Movement Sleep Time between GPS checks. It continues this for as long as the jostle continues and no GPS movement is detected.
- The Jostle Upload Delay and Maximum Jostle Upload Delay are the timing parameters relevant to the Advanced Tracking -> Upload On Jostle option.
- The Jostle Upload Delay is the number of seconds to wait after a jostle before scheduling an upload.
- The Maximum Jostle Upload Delay prevents the upload being rescheduled (delayed) indefinitely during continuous jostling by forcing it to take place within a specified number of seconds after the jostling begins.
- The Jostle Upload Threshold optionally limits these uploads to those that show appreciable movement.
Jostle Mode Wake Filter
By default the Oyster3 is in GPS Tracking Mode. Trips can be started based purely on accelerometer movement (vibration) by updating the tracking mode to Jostle Trips. If updating to Jostle Trips, the wake filter parameters would be found in Jostle Tracking Mode Wake Filter.
- 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
Disabling the Wake Filter
The Wake Filter is a setting that 'filters' out the small movements noticed by the accelerometer so the device doesn't start a trip if it is bumped once. You can use this feature to track very small movements such as machinery operation, or vibrations. To disable the wake filter, it would be found in Jostle Trips and would need to set Disable Wake Filter to Yes.
Common Queries/Set Up
Below provides example set ups on different scenarios
We can try extending the Wakeup Delay, and reducing the No Movement Limit.
In the event you would like the device to be placed in a trip on the slightest movement, it can be set to jostle mode and disable the wake filter.