Indoor RF Tracking

In general, the beacons (with fixed location coordinates) are periodically broadcasting their positions. Those beacons can be placed, for example inside a warehouse, creating a detection zone for the assets containing a TraceME module. The beacons are connected to a standard network, and a central computer or server, which tracks the position of the modules.

The TraceME module receives the transmitted beacon signals and calculates its own relative position. Practically most of the time, the objects are not being moved. In this situation the module is in its ‘deep sleep’ state and optionally transmits its location back to the beacons once a day/week/month, consuming a minimum of battery power. All TraceME modules are equipped with multiple on-boards sensors, including a 3D accelerometer, which is active in the module’s ‘deep sleep’ state. When an object is being moved, the accelerometer triggers the module into its ‘active’ state, transmitting its location and other relevant module information (e.g. battery- and I/O status, temperature, etc) back to the fixed beacons.

Listen before talk

The TraceME module is installed in the vehicle, or attached to the object, and remains inactive until the vehicle/objects needs to be located. This ‘listen before talk’ algorithm is essential for a succsful anti-theft systems, since criminal gangs often try to locate and disable most RF transmitting devices. For battery powered devices which are being used for example in logistic applications, minimizing RF-transmissions enlarges the module’s battery lifetime.

Triangulation

Radio propagation systems (especially indoor) are facing many practical difficulties like reflections and obstructions, caused by specific site parameters such as floor layout, walls, and numerous reflecting surfaces. However, by using a minimum of three transmitting beacons and an intelligent software algorithm, accurate (up to 50 cm) indoor positioning based on triangulation is possible.

Stolen vehicle/object recovery

When a module is actually moved out of the RF-range of the beacons, the module can no longer calculate its position and goes into its ‘out-of-range’ state. This could be the case, for example, if an object is being stolen. Depending on the type of the TraceME modules, they are equipped with several technologies to recover the stolen object. In the ‘out-of-range’ state, the module tries to find its current position by using GPS, or optional Iridium satellite, or sense the availability of surrounding cellular GSM- or LoRa networks.