When you set up InSight Alerts™, the system monitors the regular reports from vehicles to detect when a vehicle does what you are looking for.
When the system detects that the vehicle has done what you are looking for, the alert goes on. The alert stays on until a subsequent report indicates that the vehicle is no longer doing what you are watching for, at which point it is turned off.
An alert can go on and off without you ever seeing an indication that the condition was met. That is because each alert has an associated time to trigger. The time to trigger allows you to ignore transient states that do not concern you. For example, if a vehicle temporarily exceeds the speed limit while overtaking another vehicle, you probably do not want to be notified of a speeding alert. InSight Alerts only report exceptions that are still on after the time to trigger has elapsed. Once an alert triggers, you can see it in the InSight Alerts Inbox and any email notifications associated with the alert are sent.
There are two ways that an alert can trigger:
- If the alert is aggressive, it triggers as soon as the minimum time to trigger elapses, without waiting for another message to confirm that it is still on.
- If the alert is not aggressive, it triggers at the first regularly scheduled report that occurs after the time to trigger elapses. That is, if the time to trigger is not zero, the system waits for confirmation that the alert is still on.
When the time to trigger is zero, there is no distinction between aggressive and non-aggressive alerts: the alert triggers as soon as the alert goes on.
Note that making an alert aggressive can lead to false positives. The following example illustrates how this can occur:
A vehicle has a regularly scheduled report interval of 3 minutes. It starts speeding to overtake another vehicle 1 minute after a regularly scheduled report, and continues to exceed the speed limit for a total of 4 minutes. The minimum time before triggering the speeding alert has been set to 5 minutes. After returning to a valid speed, the vehicle moves temporarily out of range of any cellular coverage, so that the next report is delayed. These events are illustrated in the following time line:
- At 0 minutes, the regular report indicates no exception.
- At 1 minute, the vehicle starts speeding. Because there is no report at that time, the system is unaware of the exception.
- At 3 minutes, the vehicle sends its next regularly scheduled report. When this report is received, the alert goes on.
- At 5 minutes, the vehicle stops speeding.
- At 6 minutes, the vehicle generates its next regularly scheduled report. This report includes the information that the exception has stopped. However, this report is delayed because the vehicle is temporarily out of range of any cellular coverage, so the system does not yet know to turn the alert off.
- At 8 minutes, the system does not yet know that the alert should be turned off because it has received no reports since the one at 3 minutes. At this point, an aggressive alert triggers.
- At 9 minutes, the vehicle is back in range, and the reports for 6 minutes and for 9 minutes come in. Based on these reports, the alert is turned off as of time 6 minutes. However, because the alert was aggressive, it has already triggered at 8 minutes: any emails associated with the alert have been sent and the alert appears in the InSight Alerts Inbox. If the alert was not aggressive, this is the point when a decision is made whether the alert triggers or not (and it would not because the vehicle was not speeding for five minutes).