Patent ID: 8342027

Claim:
A method for determining an unknown physical property of an object or fluid in a dynamic multi-path clutter environment, the method comprising: transmitting an RF interrogation signal to a wireless sensor physically coupled to the object or the fluid in the dynamic multi-path clutter environment wherein the transmitted RF interrogation signal generates multipath ringdown signals in the dynamic multi-path clutter environment; receiving a retransmitted reference signal and a retransmitted measurement signal from the wireless sensor, wherein the structure of the wireless sensor is such that, upon receipt of the RF interrogation signal, the wireless sensor produces a reference signal and a measurement signal and retransmits the reference signal and the measurement signal in the dynamic multi-path clutter environment, and wherein the retransmitted reference signal and the retransmitted measurement signal are derived from the RF interrogation signal, the retransmitted reference signal is delayed by a first time delay, the retransmitted measurement signal is delayed by a second time delay that is a function of the unknown physical property, the first and second time delays are associated by a known relationship defined by the wireless sensor and are each long enough to permit retransmission of the reference and measurement signals without substantial overlap in time with the multipath ringdown signals generated by the RF interrogation signal, and the first and second time delays are such that a time period between retransmission of the reference signal and the measurement signal is sufficiently short to minimize data burst calibration errors due to the dynamics of the multi-path clutter environment; using a comparison of the retransmitted reference signal and the retransmitted measurement signal in the time domain to determine the unknown physical property of the object or fluid.