System and method for measurement of material property using variable reflector

• US 10,247,680 B2
• Filed: 06/27/2014
• Issued: 04/02/2019
• Est. Priority Date: 06/28/2013
• Status: Active Grant

• Current Assignee: Sensors & Software Inc.
• Original Assignee: Sensors & Software Inc.
• Inventors: Annan, Peter, Redman, David
• Primary Examiner(s): Astacio-Oquendo, Giovanni
• Application Number:
  US14/392,282
• Publication Number:
  US 20160187266A1
• Time in Patent Office: 1,740 Days
• Field of Search: 324640, 324639, 324637, 324629, 324600
• CPC Class Codes: G01N 22/00 Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more G01N3/00 - G01N17/00, G01N24/00 take precedence
• CPC Class Codes: G01N 22/04 Investigating moisture content
• CPC Class Codes: G01N 33/246 for water content for control of watering A01G25/167
• CPC Class Codes: G01N 33/383 Concrete, cement
• CPC Class Codes: G01N 33/46 Wood
• CPC Class Codes: G01S 7/41 using analysis of echo signal for target characterisation; Target signature; Target cross-section

Abstract

A system and method for measuring a material includes at least one transmitter for transmitting a first signal and a second signal. A variable reflector reflects a portion of the first signal at a first reflecting property to produce a first reflected signal, the portion of the first signal having traveled through the material. The variable reflector also reflects a portion of the second signal at a second reflecting property to produce a second reflected signal, the portion of the second signal having traveled through the material. A receiver receives the first received signal and the second received signal, the first received signal includes the first reflected signal having traveled through the material and the second received signal includes the second reflected signal having traveled through the material. The first reflected signal and the second reflected signal providing an indication of at least one property of the material. The at least one property includes permittivity, attenuation, anisotropy, and frequency dependency of the material.

Claims

1. A system for measuring at least one physical property of a material, the system comprising:

at least one transmitter configured to transmit at least a first signal and a second signal;

at least one variable reflector configured to reflect a portion of the first signal to produce a first reflected signal, the portion of the first signal having traveled through the material, and configured to reflect a portion of the second signal to produce a second reflected signal, the portion of the second signal having traveled through the material;

at least one receiver configured to receive at least a first received signal and at least a second received signal, the first received signal comprising the first reflected signal having traveled through the material and the second received signal comprising the second reflected signal having traveled through the material; and

a processor in communication with the at least one receiver;

wherein

the at least one variable reflector is configured to reflect the portion of the first signal with a reflecting property having a first reflecting property value;

the at least one variable reflector is configured to reflect the portion of the second signal with the reflecting property having a second reflecting property value that is different from the first reflecting property value;

the at least one variable reflector is adjustable to change the value of the reflecting property by adjusting a reflectivity of the at least one variable reflector; and

the processor is configured to determine the at least one physical property of the material using the first received signal and the second received signal.

2. The system of claim 1, wherein the at least one transmitter is configured to transmit the first signal and the second signal temporally spaced apart.

3. The system of claim 2, wherein temporally spacing apart the transmitting of the first signal and the second signal permits independent observation of the first reflected signal and the second reflected signal.

4. The system of claim 1, wherein the first signal and second signal are the same.

5. The system of claim 1, wherein:

the processor is configured to isolate the first reflected signal and the second reflected signal, and determine at least one physical property of the material using the isolated reflected signals.

6. The system of claim 5, wherein the first received signal further comprises an unreflected portion of the first signal and the second received signal further comprises an unreflected portion of the second signal, and wherein the processor is configured to isolate the first reflected signal and the second reflected signal from the unreflected portion of the first signal and the unreflected portion of the second signal by calculating a difference between the first received signal and the second received signal.

7. The system of claim 1, wherein the at least one property of the material comprises the dielectric permittivity of the material.

8. The system of claim 1, wherein the at least one property of the material comprises the attenuation coefficient of the material.

9. The system of claim 1, wherein the at least one transmitter is configured to transmit the first signal as a transient pulse and the second signal as a transient pulse;

and

the processor is configured to determine a first time delay between transmitting the first signal and a corresponding pulse in the first received signal and a second time delay between transmitting the second signal and a corresponding pulse in the second received signal and to determine the at least one property of the material using the first time delay and the second time delay.

10. The system of claim 1, wherein the at least one transmitter is configured to transmit the first signal as a periodic signal and the second signal as a periodic signal having the same period as the first signal, and

the processor is configured to determine a first phase delay between the first signal and the first received signal and a second phase delay between the second signal and the second received signal and to determine the at least one property of the material using the first phase delay and the second phase delay.

11. The system of claim 1, wherein the variable reflector is adjustable between a first directional reflectivity to reflect signals having a first polarization, and a second directional reflectivity to reflect signals having a second polarization;

and wherein the processor is further configured to determine the anisotropy of the material.

12. The system of claim 11, wherein the first polarization and the second polarization are orthogonal.

13. The system of claim 12, wherein the first reflecting property value and the second reflecting property value are direction-independent.

14. The system of claim 1, wherein the at least one transmitter is configured to transmit the first signal with a first polarization and to transmit the second signal with a second polarization, and the processor is further configured to determine an anisotropy of the material.

15. The system of claim 14, wherein the first polarization and the second polarization are orthogonal.

16. The system of claim 1, wherein

the at least one transmitter is configured to transmit the first signal in a first frequency range and to transmit the second signal in a second frequency range;

the first reflecting property value is a reflectivity for the first frequency range and

the second reflecting property value is a reflectivity for the second frequency range; and

the processor is configured to determine frequency dependent properties of the material.

17. The system of claim 1, wherein the first signal has a differentiable amplitude in a first frequency range and the second signal has a differentiable amplitude in a second frequency range, and wherein at least one property of the material includes frequency dependent properties of the material.

18. The system of claim 1, further comprising a controller configured to select the value of the reflecting property of the variable reflector.

19. The system of claim 18, wherein the second signal is transmitted after the first signal, and wherein the controller is configured to select the first reflecting property value before the variable reflector reflects the portion of the first signal and to select the second reflecting property value before the variable reflector reflects the portion of the second signal.

20. A system for measuring a material, the system comprising:

at least one transmitter for transmitting at least a first signal and a second signal;

at least one variable reflector for reflecting a portion of the first signal at a first reflecting property to produce a first reflected signal, the portion of the first signal having traveled through the material, and for reflecting a portion of the second signal at a second reflecting property to produce a second reflected signal, the portion of the second signal having traveled through the material;

at least one receiver for receiving at least a first received signal and at least a second received signal, the first received signal comprising the first reflected signal having traveled through the material and the second received signal comprising the second reflected signal having traveled through the material, the first reflected signal and the second reflected signal providing an indication of at least one property of the material; and

a controller for selecting a reflecting property of the variable reflector;

wherein the transmitter sequentially transmits a plurality of signals; and

wherein the variable reflector reflects a first subset of the plurality of signals at the first reflecting property and reflects a second subset of the plurality of signals at the second reflecting property;

wherein the controller adjusts the reflecting property of the variable reflector during the transmission of the plurality of signals.

21. The material measurement system of claim 20, wherein the controller adjusts the reflecting property of the variable reflector independently of the timing of the sequential transmissions of the plurality of signals.

22. A method for measuring a material, the method comprising:

transmitting at least a first signal into the material and a second signal into the material;

controlling at least one reflector to reflect a portion of the first signal at a first reflecting property to produce a first reflected signal, the portion of the first signal having traveled through the material;

controlling the at least one reflector to reflect a portion of the second signal at a second reflecting property to produce a second reflected signal, the portion of the second signal having traveled through the material;

receiving at least a first received signal and at least a second received signal, the first received signal comprising the first reflected signal having traveled through the material and the second received signal comprising the second reflected signal having traveled through the material, the first reflected signal and the second reflected signal providing an indication of at least one property of the material.