Radiation source detection by recording spectral records at different times or locations and collating the spectral records

• US 6,021,269 A
• Filed: 04/09/1997
• Issued: 02/01/2000
• Est. Priority Date: 10/14/1994
• Status: Expired due to Fees

• Current Assignee: TEL Evaluations Limited
• Original Assignee: Owen Melfyn Lewis
• Inventors: Lewis, Owen Melfyn
• Primary Examiner(s): VU, VIET DUY
• Application Number:
  US08/817,136
• Time in Patent Office: 1,028 Days
• Field of Search: 395/500.26, 395/500.23, 395/500.27, 707/104, 345/355, 345/356, 345/4, 345/6, 704/237, 455/150.1, 455/154.1, 455/154.2, 455/157.2, 455/160.1, 455/161.1, 455/158.1, 455/161.3, 455/184.1, 455/226.1, 455/227, 455/228, 455/229, 324/76.12, 324/76.19, 324/76.33
• US Class Current: 703/5
• CPC Class Codes: G01S 5/0009 Transmission of position information to remote stations involving assistance data G01S5/0236
• CPC Class Codes: G01S 7/021 Auxiliary means for detecting or identifying radar signals or the like, e.g. radar jamming signals
• CPC Class Codes: G06F 17/00 Digital computing or data processing equipment or methods, specially adapted for specific functions information retrieval, database structures or file system structures therefor G06F16/00

Abstract

In an apparatus and method for detecting radiation transmitters (such as "bugs" or leaky data cables), spectral records are recorded at different times and/or locations. The records are displayed graphically and compared to identify transmitters. Spurious signals, for example as caused by taxi radio transmissions, can be eliminated since these will not appear in all records. A local transmitter of the type to be detected will appear in all records for a given location, but not in records for other locations. The strength of the transmitter signal varies as the reciprocal of the distance squared, and the presence of the transmitter and its position can be located by moving the recorder and detecting the rise or fall of the displayed graphical signal.

Claims

1. A method of detecting an unknown local radiation source in an environment where other radiation sources constitute significant levels of background noise, the method comprising:

operating a radiation receiving device at different locations within a site of interest to obtain plural spectral records, each such spectral record recording a spectrum of radiation present at a respective location from the different locations; and

collating the spectral records for the site of interest to distinguish spectral features associated with a specific location from the different locations within the site from features generally present throughout the site.

2. A method according to claim 1, wherein the spectral records are collected in a computer-based analysis apparatus, the analysis apparatus being adapted by programming to display, overlaid or juxtaposed for visual comparison, graphs representing the different spectra.

3. A method according to claim 2, including:

operating the analysis apparatus to select and display superimposed in a graph one or more subsets of said spectral records, so as to allow direct visual comparison of at least a part of the spectrum, as recorded at different times and locations.

4. A method according to claim 2, including:

operating the analysis apparatus to select and display in a graph data from one or more subsets of said spectral records, so as to allow direct visual comparison of the radiation levels present at a selected frequency within the radiation spectrum at different times and different locations.

5. A method according to claim 2, including:

operating the analysis apparatus to select and display data from one or more subsets of said spectral records in a three-dimensional graph, so as to allow direct visual comparison of at least a part of the radiation spectrum, as recorded at different times or at different locations, the three-dimensional graph having a first axis representing radiation frequency, a second axis representing radiation strength, and a third axis along which the different records are separated.

6. A method according to claim 5, further comprising operating the analysis apparatus to display a two-dimensional graph of signal strength at a selected frequency, corresponding to a cross-section of the three-dimensional graph parallel to the third axis.

7. A method according to claim 5, wherein in said two-dimensional graph spectral records are sorted according to location, date, time or weekday.

8. A method according to claim 2, wherein the analysis apparatus is operated so as to:

identify peaks of signal strength in a given spectral record, according to user defined criteria;

select a peak of interest from among the identified peaks; and

display the selected peak juxtaposed with corresponding portions of other spectral records so as to enable visual comparison.

9. A method according to claim 8, wherein the strengths of the different spectral records at the frequency of the selected peak are displayed on a two-dimensional graph.

10. A method according to claim 1, wherein said radiation receiving devices comprises a radio frequency scanning receiver.

11. A method according to claim 10, wherein the receiver provides harmonic scanning, such that activity at a given frequency of radiation is recorded at a plurality of frequencies in each recorded spectrum.

12. A method according to claim 10, wherein each spectral record represents activity recorded over a plurality of successive scans of the receiver frequency, each scan taking a finite period of time.

13. A method according to claim 12, wherein the receiver outputs a strength value for each of a plurality of frequency bins and the strength value for each bin is updated in response to each successive scan only if it exceeds the strength value obtained in previous scans.

14. A method according to claim 1, wherein a plurality of spectral records are made for each location during different time periods, and wherein plural spectral records for a given location are compared to distinguish spectral features permanently associated with the given location from transient spectral features that appear to be associated with the given location only because of the time of making a particular spectral record.

15. A radiation monitoring method comprising:

operating a radiation receiving device to obtain plural spectral records, each record comprising a spectrum of radiation present at a given time and location;

collecting the spectral records in a computer-based analysis apparatus having a display; and

operating the analysis apparatus to select and display superimposed in a graph one or more subsets of said spectral records, so as to allow direct visual comparison of the spectrum present at different times or locations.

16. A radiation monitoring method comprising:

operating a radiation receiving device to obtain plural spectral records, each record comprising a spectrum of radiation present at a given time and location;

collecting the spectral records in a computer-based analysis apparatus having a display; and

operating the analysis apparatus to select and display in a graph data from one or more subsets of said spectral records, so as to allow direct visual comparison of the radiation levels present at a given frequency in the radiation spectrum at different times or different locations.

17. A radiation monitoring method comprising:

operating a radiation receiving device to obtain plural spectral records, each record comprising a spectrum of radiation present at a given time and location;

collecting the spectral records in a computer-based analysis apparatus having a display; and

operating the analysis apparatus to select and display in a three-dimensional graph data from one or more subsets of said spectral records, so as to allow direct visual comparison of at least a part of the radiation spectrum at different times or at different locations, the three-dimensional graph having a first axis representing radiation frequency, a second axis representing radiation strength, and a third axis along which the different records are separated.

18. A method according to claim 17, further comprising operating the analysis apparatus to display a two-dimensional graph of signal strength at a selected frequency, corresponding to a cross-section of the three-dimensional graph parallel to the third axis.

19. A method according to claim 18, wherein in said two-dimensional graph spectral records are sorted by the analysis apparatus according to location, date, time or weekday.

20. An analysis apparatus for use in detecting an unknown radiation source in an environment where other radiation sources constitute significant levels of background noise, the apparatus comprising:

a receiver for receiving plural spectral records obtained by a radiation receiving device operated at different locations within a site of interest, each spectral record recording the spectrum of radiation present at a respective location; and

a collator for collating the spectral records for the site of interest to distinguish spectral features associated with a specific location within the site from features generally present throughout the site.

21. An apparatus according to claim 20 in the form of a programmed computer, the collator comprising means adapted by programming to display, juxtaposed for visual comparison, graphs representing the different spectra.

22. An apparatus according to claim 20, wherein the collator includes:

means adapted to select and display superimposed in a graph one or more subsets of said spectral records, so as to allow direct visual comparison of at least a part of the spectrum, as recorded at different times and locations.

23. An apparatus according to claim 20, wherein the collator includes:

means adapted to select and display in a graph data from one or more subsets of said spectral records, so as to allow direct visual comparison of the radiation levels present at a selected frequency within the radiation spectrum at different times and different locations.

24. An apparatus according to claim 20, wherein the collator includes:

means adapted to select and display data from one or more subsets of said spectral records in a three-dimensional graph, so as to allow direct visual comparison of at least a part of the radiation spectrum, as recorded at different times or at different locations, the three-dimensional graph having a first axis representing radiation frequency, a second axis representing radiation strength, and a third axis along which the different records are separated.

25. An apparatus according to claim 24, wherein the collator further comprises means adapted to display a two-dimensional graph of signal strength at a selected frequency, corresponding to a cross-section of the three-dimensional graph parallel to the third axis.

26. An apparatus according to claim 24, wherein said two-dimensional graph spectral records are sorted according to location, date, time or weekday.

27. An apparatus according to claim 20, wherein the collator includes:

means for identifying peaks of signal strength in a given spectral record, according to user defined criteria;

means for the user to select a peak of interest from among the identified peaks; and

means for displaying the selected peak overlaid or juxtaposed with corresponding portions of other spectral records so as to enable visual comparison.

28. An apparatus according to claim 27, wherein the strengths of the different spectral records at the frequency of the selected peak are displayed on a two-dimensional graph.

29. An apparatus according to claim 20, specifically adapted to receive and collate plural spectral records made at different times at a common location.

30. An apparatus according to claim 20, specifically adapted to receive spectral records from a radiation receiving device in the form of a radio frequency scanning receiver.

31. An apparatus according to claim 20, wherein said receiver comprises a direct communications link for a local radiation receiving device.

32. An apparatus according to claim 20, wherein said receiver includes a means for receiving spectral records from a remote radiation receiving device.

41. A record carrier or signal conveying instructions for causing a programmable processing apparatus to become configured as an apparatus as claimed in claim 20 or claim 37.

33. A radiation monitoring method, comprising the steps of:

operating a radiation receiving device to obtain plural spectral records, each such record comprising a spectrum of radiation present at a given time and location;

collecting the spectral records in a computer-based analysis apparatus having a display; and

operating the analysis apparatus to select and display data from a plurality of said spectral records, so as to allow direct visual comparison thereof.

34. A method according to claim 33, wherein the radiation receiving device is operated to obtain each of said spectral records at a different respective time at the same location.

35. A method according to claim 33, wherein the radiation receiving device is operated to obtain at least one spectral record at a plurality of different respective locations.

36. A method according to claim 35, wherein the radiation receiving device is operated to obtain a plurality of spectral records at each respective location, each being recorded at a different respective time.

37. An analysis apparatus for use in monitoring radiation, comprising:

a receiver for receiving plural spectral records, each record comprising a spectrum of radiation recorded by a radiation receiving device at a given time and location;

a store for storing the spectral records in accordance with time and location of recording; and

a selector for selecting data from a plurality of the spectral records for display so as to allow direct visual comparison thereof.

38. An apparatus according to claim 37, wherein the selector is operable to select data from one or more subsets of the spectral records as selected data and to generate data for display showing the selected data superimposed in a graph which allows direct visual comparison of the spectrum present at different times or locations.

39. An apparatus according to claim 37, wherein the selector is operable to select data from one or more subsets of the spectral records as selected data and to generate data for display showing the selected data in a graph which allows direct visual comparison of the radiation levels present at a given frequency in the radiation spectrum at different times or different locations.

40. An apparatus according to claim 37, wherein the selector is operable to select data from one or more subsets of the spectral records as selected data and to generate data for display showing the selected data in a three-dimensional graph which allows direct visual comparison of at least a part of the radiation spectrum at different times or at different locations, the three-dimensional graph having a first axis representing radiation frequency, a second axis representing radiation strength, and a third axis along which the different records are separated.