Technique and electronic circuitry for quantifying a transient signal using threshold-crossing counting to track signal amplitude

• US 7,113,876 B2
• Filed: 09/08/2004
• Issued: 09/26/2006
• Est. Priority Date: 09/08/2004
• Status: Expired due to Fees

• Current Assignee: SenTech Biomed Corporation
• Original Assignee: SenTech Biomed Corporation
• Inventors: Zeng, Kefeng, Grimes, Craig A., Ong, Keat G.
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Barbee, Manuel L
• Application Number:
  US10/936,125
• Publication Number:
  US 20060064259A1
• Time in Patent Office: 748 Days
• Field of Search: None
• US Class Current: 702/66
• CPC Class Codes: G01N 2291/014 Resonance or resonant frequency
• CPC Class Codes: G01N 2291/02818 Density, viscosity
• CPC Class Codes: G01N 2291/0422 Shear waves, transverse waves, horizontally polarised waves
• CPC Class Codes: G01N 2291/0426 Bulk waves, e.g. quartz crystal microbalance, torsional waves
• CPC Class Codes: G01N 2291/0427 Flexural waves, plate waves, e.g. Lamb waves, tuning fork, cantilever
• CPC Class Codes: G01N 29/032 by measuring attenuation of acoustic waves
• CPC Class Codes: G01N 29/11 by measuring attenuation of acoustic waves
• CPC Class Codes: G01N 29/2412 using the magnetostrictive properties of the material to be examined, e.g. electromagnetic acoustic transducers [EMAT]; investigating the presence of flaws using eddy currents G01N27/90, magnetostrictive transducers B06B1/08, measuring magnetostrictive properties G01R33/18
• CPC Class Codes: G01N 29/4427 with stored values, e.g. threshold values
• CPC Class Codes: G01N 29/46 by spectral analysis, e.g. Fourier analysis or wavelet analysis spectral signal processing per se G06F17/14
• CPC Class Codes: G01N 9/002 using variation of the resonant frequency of an element vibrating in contact with the material submitted to analysis G01N9/34 takes precedence

Abstract

Circuitry adapted for carrying out associated techniques for: (a) calculating a damping factor, e.g., a damping ratio represented by ζ, or a quality factor Q, where ζ≈1/2Q, for a transient signal received, having been emitted from a resonator-type sensor element; (b) determining amplitude, A, of the transient signal; or (c) generating a frequency response dataset of interrelated points for the transient signal. A threshold comparison circuit is included for converting the transient signal received into a first and second digital waveform; the first digital waveform represents cycle crossings of the transient signal associated with a first threshold value, and the second digital waveform represents cycle crossings of the transient signal associated with a second threshold value. The transient signal may be converted, likewise, into third, and so on, digital waveforms, whereby the third digital waveform represents cycle crossings of the transient signal associated with a third threshold value. Respective digital counters are included, each of which is adapted for determining a total number of cycles of the first, second, third, and so on, digital waveform. A processing unit of suitable speed and capacity is employed for the calculating of the damping factor, determining an amplitude, and/or generating a frequency response dataset.

Claims

1. Circuitry for calculating a damping factor for a transient signal received having been emitted from a resonator-type sensor element, the circuitry comprising:

(a) a threshold comparison circuit adapted or converting the transient signal received into a first and second digital waveform;

said first digital waveform representing cycle crossings of the transient signal associated with a first threshold value, and said second digital waveform representing cycle crossings of the transient signal associated with a second threshold value, said first and second threshold value being less than or equal to an initial amplitude value of the transient signal received;

(b) a first and second digital counter, said first counter adapted for determining a first total cycles of said first digital waveform and said second counter adapted for determining a second total cycles of said second digital waveform; and

(c) a processing unit for the calculating of the damping factor using said first and second threshold values, and a difference between said second and first total cycles so counted.

2. The circuit of claim 1 wherein:

(a) said damping factor is a damping ratio represented by ζ

, as expressed;

$\mathrm{\zeta <br><br>}\approx <br><br>\frac{\ln <br><br>\left(A_1<br><br>\text{/}<br><br>A_2\right)}{2<br><br>\mathrm{\pi <br><br>}<br><br>\left(N_2-N_1\right)};<br><br>\mathrm{and}$

(b) said first and second threshold values being represented, respectively, by A₁ and A₂, said second and first total cycles represented, respectively, by N₂ and N₁, and said difference being represented by Δ

N=N₂−

N₁.

3. The circuitry of claim 1 wherein:

(a) said damping factor is a quality factor Q which is related to a damping ratio, ζ

≈

1/2Q, said damping ratio, ζ

, at being governed by the expression;

$\mathrm{\zeta <br><br>}\approx <br><br>\frac{\ln <br><br>\left(A_1<br><br>\text{/}<br><br>A_2\right)}{2<br><br>\mathrm{\pi <br><br>}<br><br>\left(N_2-N_1\right)};<br><br>\mathrm{and}$

(b) said first and second threshold values being represented, respectively, by A₁ and A₂, said second and first total cycles represented, respectively, by N₂ and N₁, and said difference being represented by Δ

N=N₂−

N₁.

4. The circuitry of claim 1:

(a) further comprising a receiver-element for location in proximity to the resonator-type sensor element for receiving the transient signal in electrical communication with said threshold comparison circuit and a microcontroller unit comprising said first and second digital counters and said processing unit; and

(b) wherein the resonator-type sensor element is selected from the group of sensor elements consisting of magnetoelastic elements, quartz crystal microbalance (QCM) elements, and piezoelectric acoustic wave elements.

5. The circuitry of claim 4 wherein the resonator-type sensor element is a magnetoelastic element and said receiver-element is a coil nearby which said magnetoelastic element is located for said receiving of the transient signal emitted therefrom;

and further comprising;

(a) a coil drive circuit comprising an amplifier having a tunable gain in electrical communication with said coil and a first switch disposed between said coil and said coil drive circuit for disconnecting said drive circuit during receipt of the transient signal;

(b) a second switch disposed between a direct current (dc) bias source and said coil to turn-on said dc bias during receipt of the transient signal; and

(c) an inductive element disposed between said direct current (dc) bias source and said coil.

6. The circuitry of claim 1:

(a) wherein said threshold comparison circuit is further adapted for converting the transient signal received into a third digital waveform representing cycle crossings of the transient signal associated with a third threshold value; and

(b) further comprising a third digital counter for determining a third total cycles of said third digital waveform.

7. The circuitry of claim 6 wherein:

(a) said first digital counter is further adapted to determine a number of reference clock cycles, M, associated with a reference clock waveform; and

(b) said processing unit is further adapted for calculating a resonance frequency, f, for the resonator-type sensor element said resonance frequency being governed by the expression

$f=\frac{N_0}{{\mathrm{MT}}_{\mathrm{CLK}}};<br><br>$

where said third total cycles is represented by N₀, and T_CLK represents a period of said reference clock waveform.

8. The circuitry of claim 6:

(a) further comprising a coil for receiving the transient signal, and a microcontroller unit comprising said first and second digital counters and said processing unit;

said coil in electrical communication with said microcontroller unit through said threshold comparison circuit; and

(b) wherein;

said third digital counter is external to, and in electrical communication with, said microcontroller unit;

said first digital counter is further adapted to determine a number of reference clock cycles associated with a reference clock waveform and

said third threshold value, represented by A₀, is a value greater than 2 nV.

9. The circuitry of claim 6:

(a) wherein the resonator-type sensor element is selected from the group of sensor elements consisting of magnetoelastic elements, quartz crystal microbalance (QCM) elements, and piezoelectric acoustic wave elements; and

(b) further comprising;

a coil for receiving the transient signal in electrical communication with said threshold comparison circuit and a microcontroller unit comprising said first, second, and third digital counters and said processing unit; and

said microcontroller unit further adapted for generating a frequency response data set of total-cycle values counted as a function of frequency, each said total-cycle value comprising one of said first, second, and third total cycles.

10. The circuitry of claim 9 wherein each said total-cycle value is a sum of at least said first and second total cycles counted.

11. The circuitry of claim 9 wherein each said total-cycle value is a sum of at least said first, second, and third total cycles counted.

12. A method for calculating a damping factor for a transient signal received, having been emitted from a resonator-type sensor element, the method comprising the steps of:

(a) converting the transient signal received into a first and second digital waveform;

said first digital waveform representing cycle crossings of the transient signal associated with a first threshold value, and said second digital waveform representing cycle crossings of the transient signal associated with a second threshold value, said first and second threshold value being less than or equal to an initial amplitude value of the transient signal received;

(b) determining a first total cycles of said first digital waveform and determining a second total cycles of said second digital waveform; and

(c) calculating the damping factor using said first and second threshold values, and a difference between said second and first total cycles so counted.

13. The method of claim 12 wherein:

(a) said damping factor is a damping ratio represented by ζ

, as expressed;

$\mathrm{\zeta <br><br>}\approx <br><br>\frac{\ln <br><br>\left(A_1<br><br>\text{/}<br><br>A_2\right)}{2<br><br>\mathrm{\pi <br><br>}<br><br>\left(N_2-N_1\right)};<br><br>\mathrm{and}$

(b) said first and second threshold values being represented, respectively, by A₁ and A₂, said second and first total cycles represented, respectively, by N₂ and N₁, and said difference being represented by Δ

N=N₂−

N₁.

14. The method of claim 12 wherein:

(a) said damping factor is a quality factor Q which is related to a damping ratio, ζ

≈

1/2Q, said damping ratio, ζ

, being governed by the expression;

$\mathrm{\zeta <br><br>}\approx <br><br>\frac{\ln <br><br>\left(A_1<br><br>\text{/}<br><br>A_2\right)}{2<br><br>\mathrm{\pi <br><br>}<br><br>\left(N_2-N_1\right)};<br><br>\mathrm{and}$

(b) said first and second threshold values being represented, respectively, by A₁ and A₂, said second and first total cycles represented, respectively, by and N₂ and N₁, and said difference being represented by Δ

N=N₂−

N₁.

15. The method of claim 12 further comprising the steps of:

(a) converting the transient signal received into a third digital waveform representing cycle crossings of the transient signal associated with a third threshold value; and

(b) determining a third total cycles of said third digital waveform.

16. The method of claim 15 further comprising the steps of:

(a) determining a number of reference clock cycles, M, associated with a reference clock waveform; and

(b) calculating a resonance frequency, f, for the resonator-type sensor element, said resonance frequency being governed by the expression

$f=\frac{N_0}{{\mathrm{MT}}_{\mathrm{CLK}}};<br><br>$

where said third total cycles is represented by N₀, and T_CLK represents a period of said reference clock waveform.

17. The method of claim 15 further comprising the step of generating a frequency response dataset of total-cycle values counted as a function of frequency each said total-cycle value comprising one of said first, second, and third total cycles.

18. The circuitry of claim 17 wherein each said total-cycle value is a sum of at least said first and second total cycles counted.

19. The circuitry of claim 17 wherein each said total-cycle value is a sum of at least said first, second, and third total cycles counted.

20. Circuitry for determining amplitude, A, of a transient signal received, having been emitted from a resonator-type sensor element, the circuitry comprising:

(a) a threshold comparison circuit adapted for converting the transient signal received into a first and second digital waveform;

said first digital waveform representing cycle crossings of the transient signal associated with a first threshold value, and said second digital waveform representing cycle crossings of the transient signal associated with a second threshold value, said first and second threshold value being less than or equal to an initial amplitude value of the transient signal received;

(b) a first and second digital counter, said first counter adapted for determining a first total cycles of said first digital waveform and said second counter adapted for determining a second total cycles of said second digital waveform; and

(c) a processing unit for the determining of the amplitude by using;

said first and second threshold values represented respectively, by A₁ and A₂;

a value for at least one or said total cycles; and

a difference between said second and first total cycles so counted, said difference represented by Δ

N=N₂−

N₁, wherein said second and first total cycles are represented, respectively, by N₂ and N₁.

21. The circuitry of claim 20:

(a) further comprising a receiver-element for receiving the transient signal in electrical communication with said threshold comparison circuit and a microcontroller unit comprising said first and second digital counters and said processing unit;

(b) wherein the resonator-type sensor element is selected from the group of sensor elements, consisting of magnetoelastic elements, quartz crystal microbalance (QCM) elements, and piezoelectric acoustic wave elements; and

(c) wherein said amplitude, A, is governed by the expression;

$A={A_2<br><br>\left[\frac{A_1}{A_2}\right]}^{N_2/\mathrm{\Delta <br><br>}<br><br><br><br>N}.$

22. The circuitry of claim 20:

(a) further comprising a receiver-element for receiving the transient signal in electrical communication with said threshold comparison circuit and a microcontroller unit comprising said first and second digital counters and said processing unit;

(b) wherein the resonator-type sensor element is selected from the group of sensor elements consisting of magnetoelastic elements, quartz crystal microbalance (QCM) elements, and piezoelectric acoustic wave elements; and

(e) wherein said amplitude, A, is governed by the expression;

$A={A_1<br><br>\left[\frac{A_1}{A_2}\right]}^{N_1/\mathrm{\Delta <br><br>}<br><br><br><br>N}.$

23. A method for determining amplitude, A, of a transient signal received, having been emitted from a resonator-type sensor element, the method comprising the steps of:

(a) converting the transient signal received into a first and second digital waveform;

said first digital waveform representing cycle crossings of the transient signal associated with a first threshold value, and said second digital waveform representing cycle crossings of the transient signal association with a second threshold value, said first and second threshold value being less than or equal to an initial amplitude value of the transient signal received;

(b) determining a first total cycles of said first digital waveform and determining a second total cycles of said second digital waveform; and

(c) determining the amplitude by using;

said first and second threshold values represented, respectively, by A₁ and A₂;

a value for at least one of said total cycles; and

a difference between said second and first total cycles so counted, said difference represented by Δ

N=N₂−

N₁, wherein said second and first total cycles are represented, respectively, by N₂ and N₁.

24. Circuitry for generating a frequency response dataset for a transient signal received, having been emitted from a resonator-type sensor element, the circuitry comprising:

(a) a threshold comparison circuit adapted for converting the transient signal received into a first and second digital waveform;

said first digital waveform representing cycle crossings of the transient signal associated with a first threshold value, and said second digital waveform representing cycle crossings of the transient signal associated with a second threshold value, said first and second threshold value being less than or equal to an initial amplitude value of the transient signal received;

(b) a first and second digital counter, said first counter adapted for determining a first total cycles of said first digital waveform and said second counter adapted for determining a second total cycles of said second digital waveform;

(c) a processing unit for the generating of the frequency response dataset of total-cycle values counted as a function of frequency, each said total-cycle value comprising one of said first and second total cycles; and

(d) wherein the resonator-type sensor element is selected from the group of sensor elements consisting of magnetoelastic elements, quartz crystal microbalance (QCM) elements, and piezoelectric acoustic wave elements.

25. The circuitry of claim 24 wherein each said total-cycle value is a sum of at least said first and second total cycles counted.

26. The circuitry of claim 24:

(a) wherein said threshold comparison circuit is further adapted for converting the transient signal received into a third digital waveform representing cycle crossings of the transient signal associated with a third threshold value; and

(b) further comprising a third digital counter for determining a third total cycles of said third digital waveform, wherein each said total-cycle value is a sum of at least said first, second, and third total cycles counted.

27. The circuitry of claim 26:

(a) further comprising a receiver-element for receiving the transient signal in electrical communication with said threshold comparison circuit and a microcontroller unit comprising said first, second, and third digital counters and said processing unit; and

(b) wherein said microcontroller unit is further adapted for calculating, a damping factor for the transient signal using said first and second threshold value, and a difference between said second and first total cycles so counted.

28. The circuitry of claim 27 wherein:

(a) said damping factor is a damping ratio represented by ζ

, as expressed;

$\mathrm{\zeta <br><br>}\approx <br><br>\frac{\ln <br><br>\left(A_1<br><br>\text{/}<br><br>A_2\right)}{2<br><br>\mathrm{\pi <br><br>}<br><br>\left(N_2-N_1\right)};<br><br>\mathrm{and}$

(b) said first and second threshold values being represented, respectively, by A₁ and A₂, said second and first total cycles represented, respectively, by N₂ and N₁, and said difference being represented by Δ

N=N₂−

N₁.

29. The circuitry of claim 27 wherein:

(a) said damping factor is a quality factor Q which is related to a damping ratio, ζ

≈

1/2Q, said damping ratio, ζ

, being governed by the expression;

$\mathrm{\zeta <br><br>}\approx <br><br>\frac{\ln <br><br>\left(A_1<br><br>\text{/}<br><br>A_2\right)}{2<br><br>\mathrm{\pi <br><br>}<br><br>\left(N_2-N_1\right)};<br><br>\mathrm{and}$

(b) said first and second threshold values being, represented, respectively, by A₁ and A₂, said second and first total cycles represented, respectively, by N₂ and N₁, and said difference being represented by Δ

N=N₂−

N₁.

30. A method for generating a frequency response dataset for a transient signal received, having been emitted from a resonator-type sensor element, the method comprising the steps of:

(a) converting the transient signal received into a first and second digital waveform;

said first digital waveform representing cycle crossings of the transient signal associated with a first threshold value, and said second digital waveform representing cycle crossings of the transient signal associated with a second threshold value, said first and second threshold value being less than or equal to an initial amplitude value of the transient signal received;

(b) determining a first total cycles of said first digital waveform and determining a second total cycles of said second digital waveform;

(c) generating the frequency response dataset to comprise total-cycle values counted as a function of frequency, such that each said total-cycle value comprises one of said first and second total cycles; and

(d) having selected the resonator-type sensor element from the group of sensor elements consisting of magnetoelastic elements, quartz crystal microbalance (QCM) elements, and piezoelectric acoustic wave elements.

31. The method of claim 30 wherein each said total-cycle value is a sum of at least said first and second total cycles counted.

32. The method of claim 30 further comprising the steps of:

(a) converting the transient signal received into a third digital waveform representing cycle crossing of the transient signal associated with a third threshold value; and

(b) determining a third total cycles of said third digital waveform;

wherein each said total-cycle value is a sum of at least said first, second, and third total cycles counted.

33. The method of claim 30 further comprising the steps of:

(a) generating a second frequency response dataset for a second transient signal received, having been emitted from a second resonator type sensor element said second frequency response dataset to comprise second total-cycle values counted as a function of frequency;

(b) generating a third frequency response dataset for a third transient signal received, having been emitted from a third resonator-type sensor element, said third frequency response dataset to comprise third total-cycle values counted as a function of frequency; and

(c) for each said frequency response dataset so generated, identify a respectively resonant frequency for each said respective first, second, and third sensor element by identifying a peak-value for each said respective frequency response dataset.

34. A method for generating a frequency response dataset for a transient signal received, having been emitted from a resonator-type sensor element, the method comprising the steps of:

(a) converting the transient signal received into a first, second, and third digital waveform;

said first digital waveform representing cycle crossings of the transient signal associated with a first threshold value, said second digital waveform representing cycle crossing of the transient signal associated with a second threshold value, and said third digital waveform representing cycle crossings of the transient signal associated with a third threshold value, said first, second, and third threshold value being less than or equal to an initial amplitude value of the transient signal received;

(b) determining a first total cycles of said first digital waveform, determining a second total cycles of said second digital waveform, and determining a third total cycles of said third digital waveform;

(c) generating the frequency response dataset to comprise total-cycle values counted as a function of frequency, such that each said total-cycle value is a sum of at least said first, second, and third total cycles counted; and

(d) the resonator-type sensor element having been selected from the group of sensor elements consisting of magnetoelastic elements.