Wireless sensor reader
First Claim
1. A method of obtaining a measurement from a remote location, the method comprising:
- transmitting at least one excitation pulse at a fixed frequency to a wireless sensor;
receiving at least one signal from said wireless sensor in response to said at least one excitation pulse;
sampling said received signal; and
holding the frequency of said received signal constant by a reader for a length of time sufficient to ascertain said received signal, wherein said wireless sensor is configured to change its resonant frequency in proportion to at least one sensed parameter.
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Accused Products
Abstract
A wireless sensor reader is provided to interface with a wireless sensor. The wireless sensor reader transmits a narrowband, fixed frequency excitation pulse to cause the wireless sensor to generate a ring signal. The ring signal corresponds to the value of the physical parameter being sensed. 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 low power, simple circuitry required to generate the excitation pulse allows the reader to be a small, battery operated unit. Alternative methods of frequency determination are also disclosed.
228 Citations
43 Claims
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1. A method of obtaining a measurement from a remote location, the method comprising:
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transmitting at least one excitation pulse at a fixed frequency to a wireless sensor; receiving at least one signal from said wireless sensor in response to said at least one excitation pulse; sampling said received signal; and holding the frequency of said received signal constant by a reader for a length of time sufficient to ascertain said received signal, wherein said wireless sensor is configured to change its resonant frequency in proportion to at least one sensed parameter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for obtaining a measurement from a remote location, said system comprising:
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a wireless sensor configured to change its resonant frequency in proportion to at least one sensed parameter; and a reader configured to transmit at least one excitation pulse at a fixed frequency to said wireless sensor, to receive at least one signal from said wireless sensor in response to said excitation pulse, to sample said received signal, and to hold the frequency of said received signal constant for a length of time sufficient to ascertain the frequency of said received signal. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A wireless sensor reader comprising:
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a transmit circuit configured to generate at least one excitation pulse to cause a wireless sensor to emit at least one response signal; at least one antenna configured to transmit said excitation pulse and receive said response signal; a phase-locked loop circuit configured to receive said response signal from said at least one antenna, said phase-locked loop circuit including a voltage-controlled oscillator configured to generate a count signal at a frequency related to said response signal frequency; a first circuitry configured to sample a control voltage input of said voltage-controlled oscillator; a second circuitry configured to generate a control voltage signal for input to said voltage-controlled oscillator; wherein said phase-locked loop circuit is capable of being placed in a sample mode to receive said response signal and adjust the frequency of said count signal based on the frequency of said response signal; wherein said phase-locked loop circuit is further capable of being placed in a hold mode to hold the frequency of said count signal constant to extend the duration of said count signal for a length of time sufficient to determine the frequency of said count signal; and wherein said first circuitry and said second circuitry reconfigure said phase-locked loop circuit between said sample mode and said hold mode. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
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40. A method of reading a wireless sensor comprising:
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transmitting at least one excitation pulse to a wireless sensor; receiving at least one response signal from said wireless sensor in response to said excitation pulse; amplifying said response signal;
locking an oscillator to a frequency harmonically related to said response signal;
digitally sampling the control voltage of said oscillator;
regenerating said digitally sampled control voltage of said oscillator; and
switching said regenerated voltage to control said oscillator, and holding said regenerated voltage in control of said oscillator constant for a length of time sufficient to determine the frequency of said oscillator. - View Dependent Claims (41, 42, 43)
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Specification