Detecting events

Automatic Vehicle Location (AVL) devices not just provide location and telemetry data, but can also detect certain circumstances, which might be important to user, and report about them as soon as they happen. And the smarter device is, the wider list of such events.

We listed just a few examples of such events in the table below:

Status and Monitoring Security and Sabotage Driving and Maintenance
Engine Start / Off SOS button pressed Speeding
Door opening Car alarm triggering Harsh driving
Machinery use Tow alert Long idling
Fueling, Draining Signal jamming Car crash
Geofence In / Out Antenna cut off Car battery low
Movement detection SIM card ejection Check engine (MIL)
Backup battery low Device On / Off DTC error codes

Depending on the application, specific hardware features (i.e. built-in and connected sensors) there can be even more detectable events.

Some of the events can be easily (and even better) controlled on the server side. For example, determining geofence entering / leaving with the server software gives more flexibility (e.g. drawing multiple polygonal zones) and easier to manage, especially if you have many areas or vehicles. The same applies to fueling / draining, cellular signal jamming, speeding and some other.

However, the majority of events require onboard hardware detection with instant messaging. If your GPS tracking device doesn’t report about the power supply issues, you can’t be sure about the car’s security. In business applications it’s often important to prevent sabotage by employees – and such reports as “Device switched OFF” or “SIM card ejected” help much.

How it works

The general procedure for controlling the events consists of three phases:

  • Firmware processing. There should be firmware code routines that are responsible for corresponding hardware events. For instance, the code that is monitoring the voltage of internal backup battery: when it falls below particular level, it should be noticed and the “battery low” message reported.
  • Hardware triggering. The device must have built-in or external sensors to detect physical phenomena related to the event. For example, to detect towing it must be equipped with an accelerometer (shake & movement sensor). To determine the external power supply there have to be elements in it sensitive to the voltage level.
  • Reporting. There are two primary ways to report about the event: with SMS and GPRS channel. It’s often low-cost GPS trackers use SMS messaging only, and more advanced models support both. GPRS is a cheaper, faster and more informative way to deliver information to the server platform, while SMS better suits for direct device-to-person communication.

On the server side

In all good software platforms user can flexible manage the events he wants to stay aware of, as well as the list of related assets, time schedule and areas. Furthermore, he can choose how these events should be logged and reported about: by an on-screen message, Email, SMS, automatic voice call or, maybe, by an instant notification in a mobile app.

For example, let’s assume the dispatcher must be warned with an on-screen message and email when the temperature of the carried frozen food rises above the temperature of –10°C (15°F). Then the corresponding rule will look like this: