Wireless sensor reader

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.

1 . A wireless sensor reader comprising:
 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 circuitry to process the response signal; and   a timing and control circuitry configured to activate at least one of the transmit circuit, antenna, and circuitry to process the response signal of the wireless sensor reader.   
     
     
         2 . The wireless sensor reader of  claim 1 , wherein said wireless sensor is configured to change its resonant frequency in proportion to at least one sensed parameter. 
     
     
         3 . The wireless sensor reader of  claim 1 , wherein said circuitry to process the response signal comprises a phase-locked loop. 
     
     
         4 . The wireless sensor reader of  claim 3 , wherein said phase-locked loop circuit further includes circuitry for internal calibration. 
     
     
         5 . The wireless sensor reader of  claim 1 , wherein the timing and control circuitry may place at least one of the transmit circuit, antenna, and circuitry to process the response signal of the wireless sensor reader in a reduced power mode after a specified period of inactivity. 
     
     
         6 . The wireless sensor reader of  claim 5 , wherein the specified period of inactivity is adjustable. 
     
     
         7 . The wireless sensor reader of  claim 1 , wherein the timing and control circuitry includes a configuration buffer that receives timing instructions from an external interface circuitry wherein the instructions establish a timing period before entering into a reduced power mode. 
     
     
         8 . The wireless sensor reader of  claim 1 , wherein the timing and control circuitry includes a wakeup timer to sequence the power up of at least one of the transmit circuit, antenna, and circuitry to process the response signal of the wireless sensor reader. 
     
     
         9 . The wireless sensor reader of  claim 1  further comprising a transmit timer in communication with the transmit circuitry, a receiver timer in communication with the antenna, a phase-locked loop timer in communication with a phase-locked loop, and a frequency counter timer in communication with a frequency counter. 
     
     
         10 . The wireless sensor reader of  claim 9 , wherein the timing and control circuitry is in communication with the transmit timer, the receiver timer, the phase-locked loop timer, and the frequency counter timer. 
     
     
         11 . A wireless sensor reader comprising:
 a transmit circuit configured to generate at least one excitation pulse to cause a wireless sensor to emit at least one response signal corresponding to a sensed parameter value;   at least one antenna configured to transmit said at least one excitation pulse and receive said at least one response signal;   a receiver circuit for amplifying said at least one received response signal;   a phase-locked loop;   a frequency counter;   a timing and control circuitry configured to activate at least one of the transmit circuit, antenna, receiver circuit, phase locked loop, and frequency counter of the wireless sensor reader.   
     
     
         12 . The wireless sensor reader of  claim 11  wherein said wireless sensor reader is a handheld device. 
     
     
         13 . The wireless sensor reader of  claim 11  further comprising a battery for powering said wireless sensor reader. 
     
     
         14 . The wireless sensor reader of  claim 11 , wherein the timing and control circuitry is configured to instruct the frequency counter to conduct a controlled interval count of a voltage controlled oscillator frequency of the phase-locked loop, wherein after the count, the phase locked loop is placed in sleep mode and the count value is transferred to an external interface circuitry. 
     
     
         15 . A system for reading a wireless sensor comprising:
 a wireless sensor including at least one inductor and one capacitor configured to change its resonant frequency in proportion to at least one sensed parameter; and   a reader for transmitting at least one excitation pulse to said wireless sensor and to receive at least one signal from said wireless sensor in response to said excitation pulse, wherein the reader includes:
 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; and 
 a timing and control circuitry to configure and activate components of the reader. 
   
     
     
         16 . The system of  claim 15  wherein said timing and control circuitry places each component of the reader in a powered-down mode after a specified period of inactivity. 
     
     
         17 . The system of  claim 15  wherein said timing and control circuitry further comprises a wakeup timer to communicate with a transmit timer, a receive timer, a phase-locked loop timer, and a frequency counter timer to wake up and control the respective components of the wireless sensor reader. 
     
     
         18 . The system of  claim 15 , wherein the timing and control circuitry includes a configuration buffer that receives timing instructions from an external interface circuitry wherein the instructions establish a timing period before entering into a reduced power mode. 
     
     
         19 . The wireless sensor reader of  claim 15 , wherein the timing and control circuitry includes a wakeup timer to sequence the power up of at least one of the transmit circuit, antenna, and circuitry to process the response signal of the wireless sensor reader. 
     
     
         20 . The wireless sensor reader of  claim 15  further comprising a transmit timer in communication with a transmit circuitry, a receiver timer in communication with an antenna, a phase-locked loop timer in communication with the phase-locked loop circuitry, and a frequency counter timer in communication with a frequency counter, wherein the timing and control circuitry is in communication with the transmit timer, the receiver timer, the phase-locked loop timer, and the frequency counter timer.