IMPROVEMENTS RELATING TO POSITION DETERMINATIONS

摘要

A signalling system for tracking players on a sports field or other objects in a wide range of circumstances. Scanning beams sweep over a region in which the players are active and sweep related information is simultaneously transmitted. Portable devices carried by the players detect each pass of the scanning beams and store relevant parts of the sweep related information for each beam. The information is transmitted by the devices to a central site where position calculations are carried out. Various embodiments have a range of methods for transmitting and receiving information to and from the portable devices. Position information may then be used for statistical analyses or graphical displays for example.