Determining physical properties of objects or fluids in multi-path clutter environments
First Claim
1. 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 whereinthe 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, andthe 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.
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Abstract
A method for determining a physical property of an object or fluid in a dynamic multi-path clutter environment comprises transmitting an RF interrogation signal to a wireless sensor physically coupled to the object or fluid (gas or liquid) in the dynamic multi-path clutter environment, wherein the wireless sensor is operable to receive the RF interrogation signal, produce a reference signal and a measurement signal, and retransmit the reference signal and the measurement signal in the dynamic multi-path clutter environment. The reference signal and measurement signal are delayed by the wireless sensor by an amount of time that may be a function of the unknown physical property. The method also comprises receiving the retransmitted reference signal and the retransmitted measurement signal and comparing them in the time domain in order to determine the unknown physical property of the object or fluid. The method further comprises setting the time delays of the retransmitted reference and retransmitted measurement signals to be long enough for the ringdown time to be over but not so long so that the differential time is distorted by the dynamics of the system.
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Citations
20 Claims
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1. A method for determining an unknown physical property of an object or fluid in a dynamic multi-path clutter environment, the method comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A system for determining an unknown physical property of an object or a fluid in a dynamic multi-path clutter environment, the system comprising a transponder, a wireless sensor, and a signal processing unit, wherein:
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the transponder is operable to transmit an RF interrogation signal to the 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; the transponder is further operable to receive a retransmitted reference signal and a retransmitted measurement signal from the wireless sensor in the dynamic multi-path clutter environment, produce a reference signal and a measurement signal, and retransmit the reference signal and the measurement signal in the dynamic multi-path clutter environment; the reference signal and measurement signal are derived from the RF interrogation signal; the reference signal is delayed by a first time delay; the 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; 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; and the signal processing unit is electrically coupled to the transponder and is operable to compare the reference signal and the measurement signal in the time domain and, using this comparison, determine the unknown physical property of the object or the fluid.
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Specification