Appeal No. 1997-2455
Application 08/318,235
Independent claims 29 and 30 are representative of the
invention:
29. A tag for use with a plurality of readers, a reader
interrogating a tag by transmitting a carrier, the tag
comprising:
a transducer having a resonant frequency, the resonant
frequency being settable to any one of a plurality of
predetermined values;
a modulator connected across the transducer;
a control means for causing the modulator to drive the
transducer with one or more message waveforms after
interrogation by a reader, the tag identity being embedded in
each of the message waveforms, the control means setting the
resonant frequency of the transducer.
30. A tag for use with a plurality of readers, a reader
interrogating a tag by transmitting a carrier, the tag
comprising:
a transducer;
a modulator connected across the transducer;
a control means for causing the modulator to drive the
transducer with one or more message waveforms after
interrogation by a reader;
a two-stage power developer connected across the
transducer for supplying power to the components comprising
the tag, the power developer obtaining power from the voltage
induced in the transducer by a reader's carrier, a first
portion of the power supplied by the reader's carrier being
supplied by the power developer directly to the tag
components, a second portion of the power supplied by the
reader's carrier being stored by the power developer and
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