WIRELESS SENSOR READER

• US 20140306807A1
• Filed: 04/11/2013
• Published: 10/16/2014
• Est. Priority Date: 03/15/2007
• Status: Active Grant

• Current Assignee: Endotronix, Inc.
• Original Assignee: Endotronix, Inc.
• Inventors: Rowland, Harry D., Watkins, Roger Dwight, Sundaram, Balamurugan, Ahn, In Soo, Nagy, Michael, Paul, Brian
• Granted Patent: US 10,003,862 B2
• Time in Patent Office: Days
• US Class Current: 340/10.3
• CPC Class Codes: H04Q 9/00 Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom

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.

Claims

1. A method of reading a wireless sensor comprising:

calibrating a reading device such that a correlation is obtained between an oscillator control voltage and the frequency of oscillation of said oscillator;

transmitting at least one excitation pulse from said reading device 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 said oscillator to a frequency harmonically related to said response signal;

digitally sampling the control voltage of said oscillator; and

evaluating said control voltage using said correlation to obtain said response signal frequency.

2. The method of claim 1, wherein said calibrating involves counting the frequency of said oscillator.

3. The method of claim 1, wherein said calibrating involves introduction of a reference signal having a known frequency in place of said response signal.

4. The method of claim 1, including the additional step of controlling said voltage-controlled oscillator with a reference voltage during at least a portion of the time when said response signal is not present.

5. The method of claim 1, including the additional step of supplying a reference signal for frequency locking in place of said response signal, during at least a portion of the time when said response signal is not present.

6. The method of claim 1 wherein said response signal is a ring signal.

7. 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 receive circuit for amplifying said at least one received response signal;

a digital sampling circuit for converting said at least one amplified received response signal to digital representation;

a spectrum analysis circuitry for converting said digital representation of said at least one response signal to a frequency domain representation; and

a frequency domain circuitry for processing of said frequency domain representation to determine said wireless sensor sensed parameter value.

8. The wireless sensor reader of claim 7, wherein said converting of said digital representation of said response signal to a frequency domain representation is performed at least partially by hardware.

9. The wireless sensor reader of claim 7, wherein said converting of said digital representation of said response signal to a frequency domain representation is performed at least partially by software.

10. The wireless sensor reader of claim 7 wherein said response signal is a ring signal.

11. The wireless sensor reader of claim 7 wherein said wireless sensor reader is a handheld device.

12. The wireless sensor reader of claim 7 further comprising a battery for powering said wireless sensor reader.

13. A method of reading a wireless sensor comprising:

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 at least one response signal;

sampling the value of said at least one response signal to obtain multiple time domain samples;

converting said time domain samples to the frequency domain to obtain frequency domain information; and

evaluating said frequency domain information to obtain the frequency of said response signal.

14. The method of claim 13, including the additional step of processing said frequency domain information.

15. The method of claim 13, including the additional step of analyzing said frequency domain information.

16. The method of claim 13, including the additional step of storing said frequency domain information.

17. The method of claim 13, including additional steps of:

forwarding said time domain samples to a remote processing device;

receiving said time domain samples at said remote processing device; and

evaluating said time domain samples at said remote processing device to obtain said frequency of said at least one response signal.

18. The wireless sensor reader of claim 13 wherein said response signal is a ring signal.

19. The wireless sensor reader of claim 13 further comprising the step of powering said reader with a battery.