Tracking a moving radio beacon

A radio beacon trackable by a mobile device, said beacon comprising:

• an accelerometer, a transmitter and a controller;
• said beacon configured to measure a momentary acceleration in a locally defined coordinate system (XT-YT) with origin at the beacon centre, and periodically broadcast signals communicating said measured acceleration;
• and configured to enable the mobile device to measure at least one of:
• the Difference in Time of Arrival (DToA) or Difference in Angle of Arrival (DAoA) between these signals, or Time of Arrival (ToA) or Angle of Arrival (AoA) of these signals in a mobile coordinate system (XM-YM) with origin at the mobile device centre;
• and enable the mobile device to determine the distance and direction to the beacon, based on said acceleration measurement, and on said measured at least one of:
• DToA or DAoA or ToA or AoA, by solving a set of equations wherein distance of movement of the beacon is estimated by integrating its communicated acceleration measurement by time of movement.

A mobile device for tracking a radio beacon, said device comprising:

• a receiver, an accelerometer, and a controller;
• said device configured to detect signals transmitted by the beacon indicating a momentary acceleration of the beacon measured in a beacon local coordinate system (XT-YT) with origin at the beacon centre;
• and to measure at least one of:
• the Difference in Time of Arrival (DToA) or Difference in Angle of Arrival (DAoA) between these signals, or Time of Arrival (ToA) or Angle of Arrival (AoA) of these signals;
• and determine the distance and direction to the beacon based on said communicated acceleration measurement, and on said measured at least one of:
• DToA or DAoA or ToA or AoA, by solving a set of equations wherein distance of movement of the beacon is estimated by integrating its communicated acceleration measurement by time of movement.