Identification and analysis of source emissions through harmonic phase comparison

Patent metadata

Field	Value
Publication number	US-10416286-B2
Application number	US-201313967557-A
Country	US
Kind code	B2
Filing date	Aug 15, 2013
Priority date	Oct 23, 2009
Publication date	Sep 17, 2019
Grant date	Sep 17, 2019

Abstract

The present invention is a signal processing method to significantly improve the detection and identification of source emissions. More particularly, the present invention offers a processing method to reduce the false alarm rate of systems which remotely detect and identify the presence of electronic devices through an analysis of a received spectrum the devices' unintended emissions. The invention identifies candidate emission elements and determines their validity based on a frequency and phase association with other emissions present in the received spectrum. The invention compares the measured phase and frequency data of the emissions with a software solution of the theoretically or empirically derived closed-form expression which governs the phase and frequency distribution of the emissions within the source. Verification of this relationship serves to dramatically increase the confidence of the detection.

First claim

I claim:

1. A method of determining a targeted electronic or electrical device as a source or a non-source of emission of electromagnetic energy, said method comprising the steps of:
receiving, with a receiver, coupled to an antenna, emissions of electromagnetic energy;
digitizing, with an analog-to-digital converter, an output signal from said receiver into a digitized signal;
selecting, with a processor, a spectral region of said received electromagnetic energy that spans an expected emission variation of a harmonic of said targeted electronic or electrical device, said harmonic being associated with a frequency location and a harmonic index;
selecting, with a processor, a candidate emission from said emissions of electromagnetic energy for said harmonic;
determining, with said processor, based on said frequency location, an existence of one or more additional harmonics;
identifying, with said processor, a phase and a frequency relationship between said harmonic and said one or more additional harmonics;
generating, with said processor, a time vector for each of said harmonic and said one or more additional harmonics based on phase values for said one or more additional harmonics;
identifying an existence or an absence of at least a single value in an intersection vector of all time vectors; and
determining, with said processor based on said existence or said absence of said single value, said targeted electronic or electrical device as said source or said non-source of said emission of electromagnetic energy.

2. The method of claim 1 , wherein the step of identifying said phase and frequency relationship includes a step of comparing harmonic spacing in frequency of said electromagnetic energy emission.

3. The method of claim 1 , wherein the step of identifying said phase and frequency relationship includes a step of one of measuring, comparing and a combination thereof, one of amplitude, phase, and a combination thereof between said at least two harmonics of said electromagnetic energy emission.

4. The method of claim 1 , wherein the step of identifying said phase and frequency relationship between said harmonic and said one or more additional harmonics of said electromagnetic energy emission comprises a step of revealing a phase and magnitude of said electromagnetic energy emission.

5. The method of claim 1 , wherein the step of identifying said phase and frequency relationship between said harmonic and said one or more additional harmonics of said electromagnetic energy emission comprises a step of using Fourier series of a time-domain waveform.

6. The method of claim 1 , wherein the step of identifying said phase and frequency relationship between said harmonic and said one or more additional harmonics of said electromagnetic energy emission comprises a step of generating a range of phase values.

7. The method of claim 6 , further including a step of identifying, with a time vector, a condition wherein a harmonic has an instantaneous phase within said range of phase values.

8. The method of claim 1 , wherein the step of identifying said phase and frequency relationship between said harmonic and said one or more additional harmonics of said electromagnetic energy emission includes a step of predicting a location of additional harmonics.

9. The method of claim 1 , further including a step of identifying interference unrelated to said source of said electromagnetic energy emission.

10. The method of claim 1 , wherein the step of receiving said emission of electromagnetic energy includes a step of receiving at least two emissions of electromagnetic energy, a step of using a multi-channel receiver and a step of collecting said at least two electromagnetic energy emissions simultaneously at all applicable channels.

11. The method of claim 10 , further including a step of identifying phase and frequency values of components of said at least two electromagnetic energy emissions prior to the step of identifying said at least one phase and frequency relationship between said harmonic and said one or more additional harmonics of said electromagnetic energy emissions.

12. The method of claim 1 , further comprising locating or geolocating said electronic or electrical device.

13. The method of claim 1 , further comprising determining an instantaneous phase of an underlying source signal to identify at least one short term event.

14. The method of claim 1 , further comprising differentiating harmonic content of said source from electro-magnetic background noise.

15. The method of claim 1 , further comprising detecting at least one electronically triggered event.

16. The method of claim 1 , further comprising monitoring, verifying or predicting a health of one of said electronic device, an electrical component, and a combination thereof.

17. The method of claim 1 , further comprising identifying that a set of harmonics is being related to a specific class of said electronic or electrical device.

18. The method of claim 1 , further comprising identifying that a set of harmonics is being related to a specific electronic or electrical device.

19. The method of claim 1 , wherein said emission of electromagnetic energy is an unintended emission.

20. The method of claim 1 , wherein said target electronic or electrical device comprises a pre-characterized emission pattern and pre-characterized variation.

21. The method of claim 1 , comprising amplifying, using a low noise amplifier, said emission of electromagnetic energy received with said receiver.

22. A method of determining a targeted device with a pre-characterized emission pattern and pre-characterized variation as a source or a non-source of emissions of electromagnetic energy, said method comprising:
receiving, with a sensor, emissions of electromagnetic energy in an electromagnetically noisy environment;
digitizing, with an analog-to digital converter (ADC), an output signal from said receiver into a digitized signal; and
processing said digitized signal with a processor to:
reveal a phase and a magnitude information;
identify a spectral region of said received electromagnetic energy that spans an expected emission of a harmonic h a of said targeted device, said harmonic h a being associated with a harmonic index k a ;
select a candidate emission in said spectral region for said harmonic h a ;
measure a frequency location of said candidate emission;
record, in a memory, said frequency location of said candidate emission as f a ;
determine, based on said frequency location f a , an existence of a harmonic h b , being associated with a harmonic index k b , at a frequency location f b =f a *k b /k a ;
determine, based on said frequency location f a and said existence of said harmonic h b , an existence of a harmonic h c , being associated with a harmonic index k c , at a frequency location f c =f a *k c /k a ;
measure phase values of each of said harmonic h b and said harmonic h c ;
convert, by adding an error term, each phase value into a phase range;
generate, using a Fourier series, a time vector for each harmonic h a , h b , and h c as t a , t b , and t c respectively;
determine an existence or an absence of at least a single value in an intersection vector t int of times t a , t b , and t c at which phase ranges of harmonics h a , h b , and h c occur simultaneously; and
identify said targeted device as said source of said emissions of electromagnetic energy upon existence of said at least single value i

Assignees

• Nokomis Inc

Inventors

• Freeman Stephen Dorn
• Keller Iii Walter John

Classifications

• G01V3/12

  operating with electromagnetic waves {(operating with millimetre waves G01V8/005)} · CPC title

• G01S7/38

  Jamming means, e.g. producing false echoes · CPC title

• G01R29/0892 Primary

  Details related to signal analysis or treatment; presenting results, e.g. displays; measuring specific signal features other than field strength, e.g. polarisation, field modes, phase, envelope, maximum value · CPC title

• G01S13/88

  Radar or analogous systems specially adapted for specific applications (electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00) · CPC title

• G01S7/41 Primary

  using analysis of echo signal for target characterisation; Target signature; Target cross-section · CPC title