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 device. The beacons are connected to a standard network, and a central computer or server, which tracks the position of the hardware devices.

The TraceME device 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 device 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 hardware devices are equipped with multiple on-boards sensors, including a 3D accelerometer, which is active in the device’s ‘deep sleep’ state. When an object is being moved, the accelerometer triggers the device into its ‘active’ state, transmitting its location and other relevant device information (e.g. battery- and I/O status, temperature, etc) back to the fixed beacons.

Listen before talk

The TraceME device 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 device’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 device is actually moved out of the RF-range of the beacons, the device 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 hardware devices, they are equipped with several technologies to recover the stolen object. In the ‘out-of-range’ state, the device tries to find its current position by using GPS, or optional Iridium satellite, or sense the availability of surrounding cellular GSM- or LoRa networks.