Patent ID: 8305842

Claim:
A location system, for the tracking of personnel or products for establishing the location of an identification tag attached to a person or product, the location system comprising a tag, wherein the tag comprises: (i) a power source; (ii) an ultrasonic transducer; (iii) a transmitter is connected to an output from said transducer and operable to transmit multiple frequencies to establish the unique ID of said tag in question, the location system further comprising: (iv) a plurality of strategically located ultrasonic receivers; and (v) processing means including a reader operable to process output signals from said ultrasonic receivers to establish the ID of said read tag and its location, wherein the transmitter is operable to transmit a first frequency solely to identify when said tag is about to start transmitting data, and wherein the reader incorporates a number of Goertzel filters corresponding to the number of frequencies transmitted to process the output signals from the ultrasonic receivers.