Methods and apparatus for electromagnetic signal polarimetry sensing

• US 9,857,316 B2
• Filed: 03/15/2013
• Issued: 01/02/2018
• Est. Priority Date: 01/13/2012
• Status: Active Grant

• Current Assignee: University of Notre DAME Du Lac
• Original Assignee: University of Notre DAME Du Lac
• Inventors: Pratt, Thomas G., Mueller, Jeffrey George
• Primary Examiner(s): Toatley, Gregory J
• Assistant Examiner(s): STIFTER JR, TERENCE E
• Application Number:
  US13/837,937
• Publication Number:
  US 20130332115A1
• Time in Patent Office: 1,754 Days
• Field of Search: 702 2, 342 22, 356 731, 324326, 455 73, 455118, 4551901
• CPC Class Codes: G01N 22/04 Investigating moisture content
• CPC Class Codes: G01S 13/885 for ground probing prospecting or detecting using electromagnetic waves G01V3/12
• CPC Class Codes: G01S 7/024 using polarisation effects in waveguides H01P1/165; for aerials H01Q, e.g. H01Q15/22, H01Q15/24, H01Q19/195
• CPC Class Codes: Y02A 90/10 Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Abstract

A system and method of identifying changes utilizing radio frequency polarization includes receiving a reflected and/or transmitted polarized radio frequency signal at a receiver, filtering, amplifying and conditioning the received signal, converting the received signal from an analog format to a digital format, processing the digital signal to elicit a polarization mode dispersion feature of the received signal, and comparing the polarization mode dispersion features to a known calibration to detect a change in a characteristic of the target object.

Claims

1. A method of identifying changes utilizing polarization comprising:

receiving polarized and coherent components of an at least partially polarized multipath signal at a receiver, wherein at least one signal path of the multipath signal is at least one of reflected off of a surface of a target object or transmitted through the target object;

computing the Stokes parameter versus the frequency index of the subcarrier present within the received signal;

calculating polarization as a function of frequency to determine the polarization mode dispersion of the received multipath signal;

detecting a change in a polarization mode dispersion in response to a change in the target object; and

displaying on a user interface the detected change in the polarization mode dispersion as a digital representation of the change in the target object.

2. A method as defined in claim 1, wherein detecting a change in the polarization mode dispersion in response to a change in the target object further comprises comparing the polarization features of the processed signal to a known calibration.

3. A method as defined in claim 2, wherein the known calibration is a predictive model and wherein comparing the polarization features of the processed signal to the known calibration allows for prediction of an impending change in the target object.

4. A method as defined in claim 2, wherein the known calibration is determined by measuring a polarization signature of the processed signal and comparing the measured polarization signature to a known standard measurement.

5. A method as defined in claim 1, wherein detecting a change in the polarization mode dispersion in response to a change in the target object further comprises comparing a polarization mode dispersion feature of the processed signal to a previously elicited polarization mode dispersion feature of the received signal.

6. A method as defined in claim 1, wherein detecting a change in the polarization response of the target object is indicative of a change in a characteristic of the target object comprising at least one of vibration, attitude change, mechanical fault, structural change, or foreign object contamination of the target object.

7. A method as defined in claim 1, wherein an elicited polarization feature in a first subband of the received signal is compared against an elicited polarization feature of the received signal in a second subband.

8. A method as defined in claim 1, wherein the elicited polarization feature is a polarimetric mode dispersion of at least one subband of the received signal.

9. A method as defined in claim 1, wherein detecting a change in the polarization response of the target object is indicative of a change in a characteristic of the target object comprising at least one of electrical fault, electromagnetism, reflectivity, liquid phase, or solid phase.

10. A system for identifying changes utilizing polarization comprising:

a polarized receiver for receiving polarized and coherent components of a polarized multipath signal at a receiver, wherein at least one signal path of the multipath signal is at least one of reflected off of a surface of a target object or transmitted through the target object;

a signal filter for filtering the received signal;

a signal amplifier for amplifying the received signal;

a signal conditioner for conditioning the received signal;

an analog to digital converter for converting the signal from an analog format to a digital format;

a processor for computing the Stokes parameter versus the frequency index of the subcarrier present within the received signal and calculating a polarization mode dispersion feature of the received signal,

wherein the processor detects a change in the polarization mode dispersion signature of the target object; and

a display for displaying on a user interface the detected change in the polarization mode dispersion signature of the target object.

11. A system as defined in claim 10, wherein the processor detects a change in a characteristic of the polarization mode dispersion signature of the target object by comparing the detected polarization mode dispersion signature of the dispersion signature to a known calibration stored in a memory.

12. A system as defined in claim 11, wherein the known calibration is determined by measuring the polarization mode dispersion signature of the target object and comparing the measured polarization mode dispersion signature to a known standard measurement.

13. A system as defined in claim 10, wherein detection of the change in the polarization mode dispersion signature of the target object is indicative of a change in a characteristic of the target object comprising at least one of vibration, attitude change, mechanical fault, structural change, or foreign object contamination of the target object.