METHOD AND SYSTEM FOR DETECTING MOTORIZED OBJECTS

• US 20110199861A1
• Filed: 03/12/2008
• Published: 08/18/2011
• Est. Priority Date: 03/12/2007
• Status: Abandoned Application

• Current Assignee: ELTA Systems Limited (Government of Israel)
• Original Assignee: ELTA Systems Limited (Government of Israel)
• Inventors: Lapidot, Dror
• Application Number:
  US12/530,973
• Publication Number:
  US 20110199861A1
• Time in Patent Office: Days
• US Class Current: 367/74
• CPC Class Codes: G01V 1/001 Acoustic presence detection

Abstract

Sensor unit for detecting a motorized object producing a seismic or acoustic signal in the form of at least one spectral line, comprising at least one seismic sensor or at least one acoustic sensor for collecting a signal, an analog-to-digital converter for receiving said signal and generating a digital signal, a memory for storing portions of said digital signal, and a processing unit configured for performing the following operations: generating a first set of Fast Fourier Transform (FFT) values indicative of a portion of to said signal, associating said first set of FFT values with a second set of values being a partition, calculating an entropy value H of said partition, repeating the above operations, thereby constituting a sequence of entropy values H(t) corresponding to a plurality of portions of said signal, and determining a detection in case a predetermined criterion is met, said criterion is based at least on said sequence of entropy values, thereby enabling detecting of said seismic or acoustic signal.

Claims

1. Sensor unit for detecting a motorized object producing a seismic or acoustic signal in the form of at least one spectral line, comprising:

at least one seismic sensor or at least one acoustic sensor for collecting a signal;

an analog-to-digital converter for receiving said signal and generating a digital signal;

a memory for storing portions of said digital signal; and

a processing unit configured for performing the following operations;

(i) generating a first set of Fast Fourier Transform (FFT) values indicative of a portion of said signal;

(ii) associating said first set of FFT values with a second set of values being a partition;

(iii) calculating an entropy value H of said partition;

(iv) repeating said operations (i)-(iii) thereby constituting a sequence of entropy values H(t) corresponding to a plurality of portions of said signal, and determining a detection in case a predetermined criterion is met, said criterion is based at least on said sequence of entropy values,

thereby enabling detecting of said seismic or acoustic signal.

2. A sensor unit according to claim 1 wherein said motorized object is a motor vehicle or a stationary object.

3. A sensor unit according to claim 1 further comprising a communication unit operable by said processing unit for notifying a remote unit in response to a detection of said object.

4. A sensor unit according to claim 3 wherein said communication unit is further operable for receiving communication.

5. A sensor unit according to claim 1 wherein said generating includes:

(ia) generating a first set of Fast Fourier Transform (FFT) values indicative of a portion of said signal defined by pre-selected boundary frequencies.

6. A sensor unit according to claim 1 wherein said operation (i) includes:

(ia) generating a multiplicity of first sets of Fast Fourier Transform (FFT) values indicative of a portion of said signal, each defined by pre-selected boundary frequencies;

and wherein said operations (ii)-(iii) are carried out with respect to each first set in said multiplicity of first sets.

7. A sensor unit according to claim 1 wherein said predetermined criterion is met when a predetermined number of said entropy values H(t) falls below a threshold for a predetermined duration of time.

8. A sensor unit according to claim 1 wherein said indicating includes:

(iv) associating each of said entropy H(t) values with first or second binary values, if a certain value from among said entropy values H(t) falls below or above a binary threshold, respectively; and

(v) defining detection in case said first binary value is obtained for a predetermined duration of time.

9. A sensor unit according to claim 6 wherein said indicating includes:

(iv) per set from among said multiplicity, associating each of said entropy H(t) values with a first or second binary values, if a certain value from among said entropy H(t) values falls below or above a threshold, respectively, thereby constituting a multiplicity of binary values; and

(v) defining detection in case said in case a predetermined criteria is met by said multiplicity of binary values.

10. A sensor unit according to claim 7 wherein said threshold is dynamically determined.

11. A sensor unit according to claim 7 wherein said threshold is predetermined.

12. A sensor unit according to claim 1 wherein said repeating is carried out such that said operations (i)-(iii) are carried out with respect to consecutive portions of the digital signal.

13. A sensor unit according to claim 1 wherein said repeating is carried out such that a part of each set corresponding to a portion overlaps with a part of a set corresponding to a previous or a consecutive portion.

14. A sensor unit according to claim 1 being an Unattended Ground Sensor (UGS).

15. A computerized method for detecting a seismic or acoustic signal in the form of at least one spectral line, comprising:

(i) receiving a first set of Fast Fourier Transform (FFT) values indicative of a portion of seismic or acoustic signal;

(ii) associating said first set of FFT values with a second set of values being a partition;

(iii) calculating an entropy value H of said partition; and

(iv) repeating said operations (i)-(iii) thereby constituting a sequence of entropy values corresponding to sequential portions of said signal, and indicating a detection in accordance with a predetermined criterion, said criterion is based at least on said sequence of entropy values,

thereby enabling detecting of said seismic or acoustic signal.

16. A method according to claim 15 further comprising:

(v) associating each of said entropy H(t) values with one of two possible binary values, respectively, if a certain value from among said entropy H(t) values falls below or above a threshold; and

(vi) defining detection in case said first binary value is obtained for a predetermined duration of time.

17. A method according to claim 15 wherein said threshold is dynamically determined.

18. A method according to claim 15 wherein said threshold value is predetermined.

19. A method according to claim 15 wherein said repeating is carried out such that operations (i)-(iii) are carried out on a plurality of first sets corresponding to consecutive portions of said seismic or acoustic signal.

20. A method according to claim 15 wherein said repeating is carried out such that each first set, corresponding to a portion, overlaps with a part of a first set corresponding to a previous or a consecutive portion.

21. A method according to claim 15 wherein said operation (i) includes:

(ia) receiving a first set of Fast Fourier Transform (FFT) values indicative of a portion of said signal defined by pre-selected boundary frequencies.

22. A method according to claim 15 wherein said operation (i) includes:

(ia) receiving a multiplicity of first sets of Fast Fourier Transform (FFT) values indicative of a portion of said signal, each defined by pre-selected boundary frequencies.

23. A method according to claim 15 further comprising:

(vii) transmitting a corresponding signal to a remote station in response to defining a detection.

24. A method according to claim 15 wherein said predetermined criterion is met when part of said entropy values falls below a threshold for a predetermined duration of time.

25. A method according to claim 15 wherein said indicating includes:

(vi) associating each of said entropy H(t) values with a first or second binary values, if a certain value from among said entropy H(t) values falls below or above a threshold, respectively; and

(vii) defining detection in case said first binary value is obtained for a predetermined duration of time.

26. A method according to claim 15 wherein said indicating includes:

(iv) per set from among said multiplicity, associating each of said entropy H(t) values with a first or second binary values, if a certain value from among said entropy H(t) values falls below or above a threshold, respectively, thereby constituting a multiplicity of binary values; and

(v) defining detection in case a predetermined criterion is met, said criterion is based at least on said multiplicity of binary values.

27. A method according to claim 15 wherein at least operations (i)-(iv) are carried out by an Unattended Ground Sensor (UGS) having limited power and processing sources.

28. A method according to claim 15 wherein said seismic or acoustic signal is caused by any motorized object.

29. A method according to claim 15 wherein said seismic or acoustic signal is periodic.

30. A computerized method for detecting a seismic or acoustic signal, comprising:

receiving a digital representation indicative of a time-framed portion of seismic or acoustic signal;

calculating an entropy value H of said digital representation;

repeating said calculating for a succession of time-framed portions of said signal; and

indicating a detection in case a similarity criterion is met with respect to part of said time-framed portions, said similarity criterion is based at least on an entropy reference value and on said entropy values H or derivatives thereof, thereby enabling detecting of said seismic or acoustic signal, if such signal exists.

31-35. -35. (canceled)