Communicating with implanted wireless sensor
First Claim
1. A method for determining a resonant frequency of a wireless sensor, comprising:
- adjusting a phase of an energizing signal using a first phase lock loop (PLL) by;
generating the energizing signal with a first phase and a first frequency;
receiving a calibration signal via a receiver during a first period;
sampling the calibration signal;
determining a first phase difference between the sampled calibration signal and a reference signal; and
based on the first phase difference adjusting the phase of the energizing signal to reduce the first phase difference;
adjusting a frequency of the energizing signal using a second PLL by;
energizing the wireless sensor;
receiving a sensor signal from the wireless sensor during a second period;
processing the sensor signal with the reference signal;
sampling the processed signal;
determining a second phase difference between the sampled signal and the energizing signal;
based on the second phase difference adjusting the frequency of the energizing signal to reduce the phase difference; and
determining the frequency of the energizing signal when the second PLL is locked; and
using the frequency of the energizing signal when the second PLL is locked to determine the resonant frequency of the sensor.
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Abstract
The present invention determines the resonant frequency of a sensor by adjusting the phase and frequency of an energizing signal until the frequency of the energizing signal matches the resonant frequency of the sensor. The system energizes the sensor with a low duty cycle, gated burst of RF energy having a predetermined frequency or set of frequencies and a predetermined amplitude. The energizing signal is coupled to the sensor via magnetic coupling and induces a current in the sensor which oscillates at the resonant frequency of the sensor. The system receives the ring down response of the sensor via magnetic coupling and determines the resonant frequency of the sensor, which is used to calculate the measured physical parameter. The system uses a pair of phase locked loops to adjust the phase and the frequency of the energizing signal.
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Citations
13 Claims
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1. A method for determining a resonant frequency of a wireless sensor, comprising:
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adjusting a phase of an energizing signal using a first phase lock loop (PLL) by; generating the energizing signal with a first phase and a first frequency; receiving a calibration signal via a receiver during a first period; sampling the calibration signal; determining a first phase difference between the sampled calibration signal and a reference signal; and based on the first phase difference adjusting the phase of the energizing signal to reduce the first phase difference; adjusting a frequency of the energizing signal using a second PLL by; energizing the wireless sensor; receiving a sensor signal from the wireless sensor during a second period; processing the sensor signal with the reference signal; sampling the processed signal; determining a second phase difference between the sampled signal and the energizing signal; based on the second phase difference adjusting the frequency of the energizing signal to reduce the phase difference; and determining the frequency of the energizing signal when the second PLL is locked; and using the frequency of the energizing signal when the second PLL is locked to determine the resonant frequency of the sensor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification