Patent ID: 7321290

Claim:
A method for use with a system comprising a first area-wide antenna, and nearby to the first area-wide antenna a multiplicity of passive tags, each passive tag lacking a battery, each passive tag having respective first and second passive tag antennas, and nearby to the first area-wide antenna at least first and second active tags, each active tag having respective first and second active tag antennas; the method comprising the steps of: emitting, by means of the first area-wide antenna, a power and clock field at a first frequency, the first frequency lower than 1 MHz; at each of the passive tags, receiving the power and clock field by means of its respective first passive tag antenna, deriving motive power therefrom, and generating a clock that is at least twice the frequency of the power and clock frequency, the generation achieved without use of a crystal or resonator; at each of the active tags, receiving the power and clock field by means of its respective first active tag antenna wherein each of the active tags is adapted to deriving motive power and, generating a clock that is at least twice the frequency of the power and clock frequency, the generation achieved without use of a crystal or resonator; at one of the active tags, transmitting by means of its respective second active tag antenna a data signal, the data signal phased by the clock generated at the one of the active tags; at least one of the passive tags, receiving the data signal by means of its respective second passive tag antenna, and by reference to the clock generated at the at least one of the passive tags, deriving a serial data stream therefrom.