GPS Tracking Mode Wake Filter

In regular GPS trip tracking mode, the device 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. 

1. After each wake-up, the device sleeps for a short, fixed, time. This limits the maximum rate of wake-ups, and allows the asset to get underway if it really is beginning a trip. In this case, the first GPS fix will be more likely to detect movement. 
2. If too many jostle events 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 from 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

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.

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)

Detail:

• 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.

Wake Filter

By default, a wake filter is applied so that not a single, slight jolt will begin a trip. Some sustained movement is required.

Detail:

• 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 does a scan 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.

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 Movement Trips parameter tab and would need to set Disable Wake Filter to Yes.

While in GPS mode, the device will delay the wakeup after accelerometer movement for 30s by default before checking the GPS for movement. We can determine battery life is being drained due to excessive wakeups by looking at the Device Counters. Generally accelerometer wakeups will be around 10x the number of trips. If it is significantly higher than this ratio we may want to adjust parameters.

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. This applies to the Oyster3, Yabby3 and Remora3.

Jostle Trips are not available on Edge devices, so you can just disable the wake filter.

On the Oyster3, Yabby3 and Remora3 devices, we may have configured the device to jostle mode in order to track small trips or run hours. Sometimes we may see additional trips. It is important to note that if accelerometer activity is detected, a trip will start. But we may be able to prevent very slight movements setting off a trip by increasing the wakeup threshold and count to require heavier vibration to start a trip. 

If you have a problem with false trips on the Oyster and Yabby Edge devices, you can attempt to increase the thresholds in the Accelerometer and Wake Filter settings. Increasing the thresholds may improve battery life by lowering the number of unnecessary wakeups, but it increases the chances of a trip start being missed.

These settings could help with the device reporting trips when the asset had moved a few inches, sensed vibrations and moved within a smaller range.
It is highly recommended you test different parameters to confirm what works best for your application and will sense trips when they are indeed in one.
If these settings are too high, the devices will filter movements aggressively and may not record trips when the asset is being transported.