Interrogation method for passive sensor monitoring system
First Claim
1. A method of interrogating a plurality of resonant devices to determine the respective resonant frequencies of the devices comprising the steps of:
- (1) determining, for each resonant device, an optimal interrogation frequency;
(2) repeating the interrogation of each resonant device a plurality of times at its respective optimal interrogation frequency as determined by step (1);
(3) performing spectrum estimations on the data accumulated as a result of step (2); and
(4) determining the average of the frequencies derived from step (3).
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Abstract
A method of determining the frequency of a plurality of resonant devices (for example three SAW devices) includes determining optimal interrogation frequencies for each of the devices, the optimal interrogation frequencies having maximum power spectral densities, accumulating a plurality of responses for each sensor, performing discrete Fourier transforms on the sampling results to estimate the three resonant frequencies, and averaging the results of the Fourier transforms to provide an indication of resonant frequencies. The averaging step may include the calculation of a standard deviation and the rejection of any results which fall more than a pre-determined multiple of the standard deviation from the average frequency result. The frequency determined by the method may be employed to calculate the pressure and temperature of the sensor devices. The sensor devices may be located in a vehicle tire.
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Citations
20 Claims
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1. A method of interrogating a plurality of resonant devices to determine the respective resonant frequencies of the devices comprising the steps of:
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(1) determining, for each resonant device, an optimal interrogation frequency; (2) repeating the interrogation of each resonant device a plurality of times at its respective optimal interrogation frequency as determined by step (1); (3) performing spectrum estimations on the data accumulated as a result of step (2); and (4) determining the average of the frequencies derived from step (3). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of interrogating a plurality of resonant devices to determine the respective resonant frequencies of the devices comprising the steps of:
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(1) determining, for each resonant device, an interrogation frequency; (2) repeating the interrogation of each resonant device a plurality of times at its respective interrogation frequency as determined by step (1); (3) performing spectrum estimations on the data accumulated as a result of step (2); and (4) determining the average of the frequencies derived from step (3). - View Dependent Claims (17, 18, 19, 20)
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Specification