WIRELESS SENSOR READER
First Claim
1. A wireless sensor reader comprising:
- a transmit circuit configured to generate an excitation pulse to cause a wireless sensor to emit a ring signal;
an antenna configured to transmit said excitation pulse and receive said ring signal;
a phase-locked loop circuit configured to receive said ring signal, said phase-locked loop circuit including a voltage-controlled oscillator configured to generate a count signal at a frequency related to said ring signal frequency;
a circuit for identifying a set of possible frequency values of said ring signal for an individual reading;
wherein said phase-locked loop circuit is capable of being placed in a sample mode to receive said ring signal and adjust the frequency of said count signal based on the frequency of said ring signal;
wherein at least one of said transmit circuit, said phase-locked loop circuit, said antenna, and said voltage-controlled oscillator are tunable to the identified set of possible frequency values; and
further wherein said phase-locked loop circuit is capable of being placed in a hold mode to hold the frequency of said count signal constant for a length of time sufficient to determine the frequency of said count signal.
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Accused Products
Abstract
A wireless sensor reader is provided to interface with a wireless sensor. The wireless sensor reader transmits an excitation pulse to cause the wireless sensor to generate a ring signal. The wireless sensor reader receives and amplifies the ring signal and sends the signal to a phase-locked loop. A voltage-controlled oscillator in the phase-locked loop locks onto the ring signal frequency and generates a count signal at a frequency related to the ring signal frequency. The voltage-controlled oscillator is placed into a hold mode where the control voltage is maintained constant to allow the count signal frequency to be determined. The reader uses an ambient reading or other information to select a subset of the possible ring signal frequencies, and tunes or adjusts its circuits and algorithms to focus on that subset.
54 Citations
20 Claims
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1. A wireless sensor reader comprising:
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a transmit circuit configured to generate an excitation pulse to cause a wireless sensor to emit a ring signal; an antenna configured to transmit said excitation pulse and receive said ring signal; a phase-locked loop circuit configured to receive said ring signal, said phase-locked loop circuit including a voltage-controlled oscillator configured to generate a count signal at a frequency related to said ring signal frequency; a circuit for identifying a set of possible frequency values of said ring signal for an individual reading; wherein said phase-locked loop circuit is capable of being placed in a sample mode to receive said ring signal and adjust the frequency of said count signal based on the frequency of said ring signal; wherein at least one of said transmit circuit, said phase-locked loop circuit, said antenna, and said voltage-controlled oscillator are tunable to the identified set of possible frequency values; and further wherein said phase-locked loop circuit is capable of being placed in a hold mode to hold the frequency of said count signal constant for a length of time sufficient to determine the frequency of said count signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of reading a remote sensor comprising:
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identifying a set of possible frequency values of said remote sensor for an individual reading; tuning circuits to operate in a passband defined by said set of possible frequency values; transmitting an excitation pulse to said remote sensor; receiving a ring signal from said remote sensor in response to said excitation pulse; amplifying said ring signal; generating a count signal; adjusting the frequency of said count signal to match the frequency of said ring signal; and holding the frequency of said count signal constant for a length of time to determine the frequency of said count signal. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification