This project focuses on the development of a low-cost system to track the precise 3-D position of large numbers of objects tagged with passive microwave RF transponders at short-range (3-100m) and in real time. The proposed system will allow selection, identification, tracking, and encoding of data from connected sensors to be relayed by the passive tags. These tags can address a multitude of applications, including new human-computer interfaces, robot control, animation and virtual reality, gaming, low-cost tracking of machinery and animals, search and rescue, and warehouse monitoring.