Tag tracking

摘要

A tracking system is described in which a mobile tag having an unknown position is tracked in space over time. The mobile tag transmits a signal comprising a sequence of frequency components at different frequencies. The transmitted signal is received at each of a plurality of receivers, each having a known location. Each of the receivers measures the phase of each of the tones and the phase measures are passed to a central processing unit. The central processing unit then uses the determined phase measures to determine the position of the tag at the time of the transmission. Various novel tag arrangements are described which generate new transmission signals which improve accuracy and reliability of the position measurements obtained.