Electromagnetic signal proximity detection systems and methods

• US 7,541,995 B1
• Filed: 09/25/2007
• Issued: 06/02/2009
• Est. Priority Date: 09/25/2007
• Status: Expired due to Fees

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Murphy, John J. Jr.
• Primary Examiner(s): CHEN, SHIH CHAO
• Application Number:
  US11/860,734
• Time in Patent Office: 616 Days
• Field of Search: 343/703, 343/757, 343/766, 343/893
• US Class Current: 343/703
• CPC Class Codes: H01Q 3/00 Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system means for positioning H01Q1/125

Abstract

Various methods and systems directed to electromagnetic signal proximity detection are disclosed. For example, an EM detector may include an antenna array for sensing electromagnetic radiation produced by a source of radio-frequency electromagnetic radiation, one or more amplitude demodulation circuits coupled to the antenna array configured to perform an amplitude demodulation of one or more signals provided by the antenna array to produce one or more respective demodulated output signals, and an analysis circuit coupled to the amplitude demodulation circuit configured to determine at least one relative characteristic between the antenna array and the source of radio-frequency electromagnetic radiation. The relative characteristic may be the relative distance and/or angle between the antenna array and the source of radio-frequency electromagnetic radiation. The embodiments allow for signal source detection and location determination without knowledge of the frequency of a target emitter.

Claims

1. An electromagnetic signal proximity detector comprising:

an antenna array including one or more antennas for sensing electromagnetic radiation produced by a source of radio-frequency electromagnetic radiation;

one or more amplitude demodulation circuits coupled to the antenna array, the one or more amplitude demodulation circuits configured to perform an amplitude demodulation on one or more signals provided by the antenna array, the one or more amplitude demodulation circuits producing one or more respective demodulated output signals each representative of a signal strength of the sensed electromagnetic radiation received by the antenna array; and

an analysis circuit coupled to the amplitude demodulation circuit, the analysis circuit configured to determine at least one relative characteristic between the antenna array and the source of radio-frequency electromagnetic radiation.

2. The electromagnetic signal proximity detector of claim 1, wherein the relative characteristic is the relative distance between the antenna array and the source of radio-frequency electromagnetic radiation.

3. The electromagnetic signal proximity detector of claim 2, wherein the analysis circuit is configured to determine the relative distance between the antenna array and the source of radio-frequency electromagnetic radiation based on a logarithm of the inverse square of the signal strength of the one or more respective demodulated output signals.

4. The electromagnetic signal proximity detector of claim 2, wherein the analysis circuit is configured to determine the relative distance of the antenna array and the source of radio-frequency electromagnetic radiation based on a logarithm of the inverse cube of the signal strength of the one or more respective demodulated output signals.

5. The electromagnetic signal proximity detector of claim 2, wherein the analysis circuit is configured to determine the relative distance between the antenna array and the source of radio-frequency electromagnetic radiation based on a logarithm of the inverse Nth power of the signal strength of the one or more respective demodulated output signals, wherein N is a number between about 2.0 and about 3.0.

6. The electromagnetic signal proximity detector of claim 5, wherein the analysis circuit is further configured to determine the relative angle between the antenna array and the source of radio-frequency electromagnetic radiation.

7. The electromagnetic signal proximity detector of claim 1, wherein the analysis circuit is configured to determine the relative angle between the antenna array and the source of radio-frequency electromagnetic radiation.

8. The electromagnetic signal proximity detector of claim 7, wherein the relative angle is determined by comparing the apex of the one or more demodulated output signals to timing information provided by a timing circuit operatively connected to the analysis circuit.

9. The electromagnetic signal proximity detector of claim 1, wherein the antenna array includes a single antenna configured to move by physical rotation.

10. The electromagnetic signal proximity detector of claim 1, wherein the antenna array includes a dual antenna configured to move by physical rotation.

11. The electromagnetic signal proximity detector of claim 1, wherein the antenna array includes a plurality of antennas configured to rotate virtually by means of a multiplexing circuit.

12. The electromagnetic signal proximity detector of claim 11, wherein the multiplexing circuit provides a differential signal to the one or more amplitude demodulation circuits.

13. An electromagnetic signal proximity detector comprising:

an antenna array including one or more antennas for sensing electromagnetic radiation produced by a source of radio-frequency electromagnetic radiation;

an amplitude demodulator coupled to the antenna array configured to perform an amplitude demodulation of one or more signals provided by the antenna array, the amplitude demodulator producing one or more respective demodulated output signals each representative of a signal strength of the sensed electromagnetic radiation received by the antenna array; and

an analysis circuit coupled to the amplitude demodulator, the analysis circuit configured to determine the relative distance between the antenna array and the source of radio-frequency electromagnetic radiation and the relative angle between the antenna array and the source of radio-frequency electromagnetic radiation.

14. The electromagnetic signal proximity detector of claim 13, wherein the antenna array includes a dual antenna configured to move by physical rotation.

15. The electromagnetic signal proximity detector of claim 13, wherein the antenna array includes a plurality of antennas configured to rotate virtually by means of a multiplexer, wherein the multiplexer provides a differential signal to the amplitude demodulator.

16. The electromagnetic signal proximity detector of claim 13, wherein the analysis circuit is configured to determine the relative distance between the antenna array and the source of radio-frequency electromagnetic radiation based on a logarithm of the inverse Nth power of the signal strength of the one or more respective demodulated output signals, where N is a real number between about 2.0 and about 3.0.

17. A method for detecting the presence of a source of radio-frequency electromagnetic radiation, comprising:

sensing electromagnetic radiation produced by a source using an antenna array including one or more antennas for sensing electromagnetic radiation produced by the source of radio-frequency electromagnetic radiation;

performing an amplitude demodulation process on one or more signals provided by the antenna array to produce one or more respective demodulated output signals each representative of a signal strength of the sensed electromagnetic radiation received by the antenna array; and

analyzing the one or more respective demodulated output signals to determine a relative distance between the antenna array and the source of radio-frequency electromagnetic radiation.

18. The method for detecting the presence of a source of radio-frequency electromagnetic radiation of claim 17, wherein the step of analyzing the one or more respective demodulated output signals is performed based on a logarithm of the inverse Nth power of the signal strength of the one or more respective demodulated output signals, wherein N is a number between about 2.0 and about 3.0.

19. The method for detecting the presence of a source of radio-frequency electromagnetic radiation of claim 17, wherein the antenna array includes a plurality of antennas configured to rotate virtually.

20. The method for detecting the presence of a source of radio-frequency electromagnetic radiation of claim 17, wherein the step of analyzing the one or more respective demodulated output signals includes the step of determining a relative angle between the sensing means and the source of radio-frequency electromagnetic radiation based on the one or more respective demodulated output signals.