System And Method For Pressure Wave Transmission And Measurement

• US 20080037371A1
• Filed: 08/03/2007
• Published: 02/14/2008
• Est. Priority Date: 08/09/2006
• Status: Active Grant

• Current Assignee: New Jersey Institute of Technology
• Original Assignee: New Jersey Institute of Technology Office of Research and Development
• Inventors: Chang, Timothy, Cheng, Biao
• Granted Patent: US 7,492,668 B2
• Time in Patent Office: Days
• US Class Current: 367/137
• CPC Class Codes: G01S 7/52004 Means for monitoring or calibrating short-range imaging G01S7/5205
• CPC Class Codes: G01S 7/524 Transmitters
• CPC Class Codes: G01S 7/539 using analysis of echo signal for target characterisation; Target signature; Target cross-section

Abstract

A system and method for measurement are disclosed which may include providing an input command signal; convolving the input command signal with a plurality of impulse signals to produce a transducer drive signal; and activating a first pressure transducer with the drive signal to transmit a pressure wave output from the transducer.

Claims

1. A method for measurement comprising:

providing an input command signal;

convolving the input command signal with a plurality of impulse signals to produce a transducer drive signal; and

activating a first pressure transducer with the drive signal to transmit a pressure wave output from the transducer.

2. The method of claim 1 further comprising:

transmitting the pressure wave output toward a target using the first pressure transducer; and

receiving reflected pressure wave energy from the target at a second pressure transducer.

3. The method of claim 2 further comprising:

calculating at least one geometric characteristic of a surface topology of the target based on the reflected pressure wave energy.

4. The method of claim 2 wherein the target includes a heterogeneous three-dimensional structure.

5. The method of claim 4 further comprising:

calculating at least one acoustic property of the structure.

6. The method of claim 1 further comprising:

transmitting the pressure wave output from a first point along a medium to a second point along a medium using the first pressure transducer;

receiving pressure wave energy using a second pressure transducer located at the second point along the medium; and

calculating at least one characteristic of the medium based on the received pressure wave energy.

7. The method of claim 6 wherein the medium includes at least one material selected from the group consisting of:

solid, liquid, and gas.

8. The method of claim 6 wherein the medium includes at least one material selected from the group consisting of:

bone, body tissue, wood, metal, concrete, plastic, glass, and ceramic.

9. The method of claim 1 wherein the input command signal is a function selected from the group consisting of:

a rectangular step function;

a triangular function;

a sinusoidal function; and

a Gaussian function.

10. The method of claim 1 wherein the convolving step comprises:

convolving the input command signal with first and second impulse signals.

11. The method of claim 8 wherein the second impulse signal has a lower magnitude than the first impulse signal.

12. The method of claim 1 wherein the transmitting step comprises:

transmitting only a selected number of cycles of the pressure wave output.

13. The method of claim 1 wherein the pressure wave output comprises an acoustic signal.

14. The method of claim 13 wherein the acoustic signal is one of:

a) subsonic; and

b) ultrasonic.

15. The method of claim 13 wherein the acoustic signal has a frequency within a range audible to human beings.

16. The method of claim 13 wherein the acoustic signal has a frequency between 20 Hz (Hertz) and 18 kHz (kilohertz).

17. The method of claim 1 wherein a first said impulse signal has an amplitude A₁ equal to about:

1/(1+M_pⁿ), wherein

$M_p^n={\left({\mathrm{<br><br>}}^{-\frac{\mathrm{\zeta <br><br>}<br><br><br><br>\mathrm{\pi <br><br>}}{\sqrt{1-{\mathrm{\zeta <br><br>}}^2}}}\right)}^n,$

ζ

is the damping factor; and

n is the number of half ringing cycles.

18. The method of claim 17 wherein a second said impulse signal has an amplitude A₂ equal to about:

M_pⁿ/(1+M_pⁿ), wherein

$M_p^n={\left({\mathrm{<br><br>}}^{-\frac{\mathrm{\zeta <br><br>}<br><br><br><br>\mathrm{\pi <br><br>}}{\sqrt{1-{\mathrm{\zeta <br><br>}}^2}}}\right)}^n,$

ζ

is the damping factor; and

n is the number of half ringing cycles.

19. The method of claim 1 wherein a first said impulse signal has an amplitude A₁ determined according to:

A₁=1/(1+M_pⁿ), wherein

$M_p^n={\left({\mathrm{<br><br>}}^{-\frac{\mathrm{\zeta <br><br>}<br><br><br><br>\mathrm{\pi <br><br>}}{\sqrt{1-{\mathrm{\zeta <br><br>}}^2}}}\right)}^n,$

ζ

is the damping factor; and

n is the number of half ringing cycles.

20. The method of claim 19 wherein a second said impulse signal has an amplitude determined according to:

A₂=M_pⁿ/(1+M_pⁿ), wherein

$M_p^n={\left({\mathrm{<br><br>}}^{-\frac{\mathrm{\zeta <br><br>}<br><br><br><br>\mathrm{\pi <br><br>}}{\sqrt{1-{\mathrm{\zeta <br><br>}}^2}}}\right)}^n,$

ζ

is the damping factor; and

n is the number of half ringing cycles.

21. The method of claim 1 wherein a time period between a first said impulse signal and a second said impulse signal is determined according to:

Δ

T=nπ

/(ω

_n√

{square root over (1−

ζ

²)}), wherein;

n is the number of half ringing cycles, ω

_n is the natural frequency of the first pressure transducer; and

ζ

is the damping factor of the first transducer.

22. The method of claim 21 wherein the drive signal includes a pulse corresponding to each said impulse signal, and wherein the pulse width of each said pulse is equal to Δ

T.

23. The method of claim 21 wherein the drive signal includes a pulse corresponding to each said impulse signal, and wherein the pulse width of each said pulse is equal to 4Δ

T/3.

24. A method for measurement comprising:

providing an input command signal;

convolving the input command signal with an impulse signal to produce a transducer drive signal;

activating a pressure transducer with the drive signal to transmit a pressure wave output from the transducer; and

setting a pulse width of the drive signal equal to a value within +/−

20% of k2π

/ω

_d where ω

_d is a ringing frequency of the transducer, and where k is equal to any integer greater than or equal 1.

25. The method of claim 24 wherein the step of setting the pulse width comprises setting the pulse width of the drive signal equal to a value within +/−

5% of k2π

/ω

_d.

26. A measurement system comprising:

a signal generator operable to;

provide an input command signal, and

convolve the input command signal with a plurality of impulse signals to produce a transducer drive signal; and

a first pressure transducer operable to transmit a pressure wave output from the transducer upon being excited by the transducer drive signal.

27. The measurement system of claim 26 wherein the signal generator comprises:

at least one timer for controlling the scheduling of the plurality of impulse signals.

28. The measurement system of claim 26 further comprising a second pressure transducer, located proximate to the first pressure transducer, for receiving reflections of the transmitted pressure wave output.

29. The measurement system of claim 26 further comprising a second pressure transducer, located at a distance D from the first pressure transducer, for receiving pressure wave energy transmitted along the distance D.

30. The measurement system of claim 29 wherein axial wave transmission occurs between the first transducer and the second transducer.

31. The measurement system of claim 26 further comprising:

at least one additional transmitting pressure transducer, thereby providing a plurality of transmitting pressure transducers; and

at least one receiving pressure transducer for receiving pressure wave energy from the plurality of transmitting pressure transducers.