Wireless sensor reader

• US 9,305,456 B2
• Filed: 04/09/2013
• Issued: 04/05/2016
• Est. Priority Date: 03/15/2007
• Status: Active Grant

• Current Assignee: Endotronix, Inc.
• Original Assignee: Endotronix, Inc.
• Inventors: Rowland, Harry, Watkins, Roger, Sundaram, Balamurugan
• Primary Examiner(s): Mehmood, Jennifer
• Assistant Examiner(s): Mortell, John
• Application Number:
  US13/859,444
• Publication Number:
  US 20130222153A1
• Time in Patent Office: 1,092 Days
• Field of Search: 340/807.02
• US Class Current: 1/1
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/6882 Anchoring means
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: G08C 17/02 using a radio link

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.

Claims

1. A method of obtaining a measurement from a remote location, the method comprising:

transmitting a plurality of excitation pulses each at a predetermined frequency to a wireless sensor wherein said predetermined frequency is determined during a period of time when said wireless sensor is not being sampled wherein each excitation pulse is transmitted at the predetermined frequency;

receiving a signal from said wireless sensor in response to said plurality of excitation pulses;

sampling and holding said received signal; and

ascertaining the frequency of said received signal;

wherein said wireless sensor is configured to change its resonant frequency in proportion to at least one sensed parameter.

2. The method of claim 1 further comprising generating a count signal at a frequency to match the frequency of said signal from said wireless sensor.

3. The method of claim 2, wherein said count signal is generated by a voltage controlled oscillator.

4. The method of claim 2, wherein the frequency of said count signal is an integer multiple of said ring signal frequency.

5. The method of claim 1, wherein said wireless sensor is a passive sensor.

6. The method of claim 5, wherein said wireless sensor comprises at least one inductor and at least one capacitor.

7. The method of claim 6, wherein at least one of said at least one inductor and said at least one capacitor changes its value in response to said at least one sensed parameter.

8. The method of claim 1, wherein each of said excitation pulses is a different frequency.

9. The method of claim 1, wherein each of said excitation pulses is a radio frequency (RF) pulse.

10. The method of claim 1, wherein said signal from a wireless sensor is a ring signal.

21. The system of claim 1, wherein said predetermined frequency is determined prior to the receipt of a signal from said wireless sensor.

22. The system of claim 1, wherein said predetermined frequency is determined before said plurality of excitation pulses is transmitted.

11. A method of obtaining a measurement from a remote location, the method comprising:

transmitting a plurality of excitation pulses to a wireless sensor, wherein said plurality of excitation pulses are spaced apart at fixed time intervals, wherein a frequency of each of said excitation pulses is determined during a period of time when the wireless sensor is not being sampled wherein each excitation pulse is transmitted at the frequency determined during a period of time when the wireless sensor is not being sampled;

receiving a signal from said wireless sensor in response to said plurality of excitation pulses;

sampling and holding said received signal; and

ascertaining the frequency of said received signal;

wherein said wireless sensor is configured to change its resonant frequency in proportion to at least one sensed parameter.

12. The method of claim 11, wherein said fixed time intervals are equal to one another.

13. The method of claim 11, wherein each of said excitation pulses is transmitted at a predetermined frequency.

14. The method of claim 11, wherein said wireless sensor is a passive device.

15. The method of claim 11 further comprising generating a count signal at a frequency to match the frequency of said signal from said wireless sensor.

16. The method of claim 15, wherein said count signal is generated by a phase locked loop circuit.

17. A system for obtaining a measurement from a remote location, said system comprising:

a wireless sensor configured to change its resonant frequency in proportion to at least one sensed parameter;

a reader configured to transmit a plurality of excitation pulses at only a fixed frequency to said wireless sensor and to receive at least one signal from said wireless sensor in response to said excitation pulses wherein said fixed frequency is determined before said plurality of excitation pulses are transmitted wherein each excitation pulse is transmitted at the fixed frequency.

18. The system of claim 17, wherein said wireless sensor comprises at least one inductor and at least one capacitor.

19. The system of claim 17, wherein said reader includes a circuit for identifying a set of possible values of said resonant frequency of said wireless sensor.

20. The system of claim 17, wherein said reader includes a circuit for identifying a set of possible values of said resonant frequency of said wireless sensor prior to the transmission of said excitation pulse.

23. The system of claim 17, wherein said fixed frequency is determined during a period of time when the wireless sensor is not being sampled.