System and method for automated alerting to geospatial anomalies

• US 6,690,316 B2
• Filed: 09/27/2002
• Issued: 02/10/2004
• Est. Priority Date: 09/27/2002
• Status: Expired due to Fees

• Current Assignee: United States Department of the Army
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Yankielun, Norbert E.
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US10/256,182
• Publication Number:
  US 20030020647A1
• Time in Patent Office: 501 Days
• Field of Search: 342/22, 342/27, 342/196, 735/84, 735/97, 735/98, 736/02, 736/43
• US Class Current: 342/22
• CPC Class Codes: G01S 13/44 Monopulse radar, i.e. simultaneous lobing
• CPC Class Codes: G01S 13/885 for ground probing prospecting or detecting using electromagnetic waves G01V3/12
• CPC Class Codes: G01S 7/412 based on a comparison between measured values and known or stored values
• CPC Class Codes: G01V 3/12 operating with electromagnetic waves operating with millimetre waves G01V8/005

Abstract

An automated inexpensive system and reliable method for detecting spatial anomalies in real time, allows an unsophisticated operator to detect hidden anomalies efficiently and safely. In a preferred embodiment, an FM-CW radar front-end communicates with a personal computer incorporating specific filter and processing circuitry, including an A/D converter and a DSP. A target volume is illuminated from just above its top surface and return signals processed using the PC as programmed with a purpose-built algorithm. Data are down-converted to audio frequencies for ease in handling using inexpensive audio frequency circuitry. For use in avoiding bridged (hidden) crevasses during operation in snowfields, a version is mounted on a long boom extending from the front of the platform on which it is installed, typically a lead vehicle of a convoy. Heretofore, expensive systems requiring full-time monitoring by a well-trained operator were the only safe and reliable solution to insure safe traversal of snowfields.

Claims

1. An inexpensive automated system integrating only the front-end of a commercial-off-the-shelf (COTS) ground-penetrating radar employing as few as one antenna, a COTS personal computer (PC) incorporating purpose-built inexpensive processing circuitry and at least one display mechanism, and as few as one specialized algorithms,

wherein said system provides automatic and timely displays of and alerts to voids beneath a surface, said displays and alerts being intuitive to any person in close proximity to said displays.

2. The system of claim 1 in which said alert is aural, wherein said aural alert indicates the relative proximity of said voids.

3. The system of claim 1 further comprising a visual alert function, wherein said visual alert function indicates at least the relative proximity of said voids.

4. The system of claim 1 further comprising both an aural and visual alert function, wherein each said aural and visual alert functions indicates the relative proximity of said voids.

5. The system of claim 1 in which said void is a crevasse.

6. The system of claim 5 in which said crevasse is a bridged crevasse, said bridge comprising snow, ice, firn, and any combination thereof.

7. The system of claim 1 in which said radar front-end is an FM-CW radar front-end, comprising:

as few as one antenna;

a transceiver in operable communication with said as few as one antenna, said transceiver incorporating a circulator;

a local oscillator in operable communication with said transceiver; and

a mixer in operable communication with said circulator.

8. The system of claim 7 in which said purpose built inexpensive Processing circuitry comprises:

a low pass filter (LPF) in operable communication with said mixer of said radar front-end;

a high pass filter (HPF) in operable communication with said LPF;

an analog-to-digital (A/D) converter in operable communication with said HPF; and

a digital signal processor (DSP) in operable communication with said A/D converter.

9. The system of claim 1 in which said PC further comprises:

a sound card; and

at least one speaker in operable communication with said sound card.

10. The system of claim 1 in which said specialized algorithm processes the same returns from operation of said radar front-end in first and second parallel channels to establish a running average of vectors in said first channel for comparison to each single vector being processed currently by said system in said second channel,

wherein said comparison permits detection of said voids.

11. The FM-CW radar front-end of claim 7 incorporated in a lightweight, inexpensive embodiment mounted on a PC board, the antenna of which may be selected from the group consisting of:

a stripline antenna, a stripline beam antenna, a Yagi stripline beam antenna, and a log periodic array (LPA) stripline beam antenna.

12. The FM-CW radar front-end of claim 11 in which said stripline antenna is a printed circuit wide-band bow-tie dipole antenna.

13. An inexpensive method of automatically detecting voids within a target volume and alerting a person proximate to a display mechanism used with said method, said voids not otherwise evident without use of methods that are expensive, time-consuming, or both, comprising:

illuminating said target volume with electromagnetic energy from a single source placed near a top surface of said volume;

processing reflections of said electromagnetic energy at derived audio frequencies to establish vectors in first and second parallel channels,

wherein a running average of said vectors is maintained in said first channel for comparison to a current vector being processed in said second channel; and

using said comparison to initiate an alert, to display status, or both.

14. The method of claim 13 in which said voids are otherwise hidden from observation.

15. The method of claim 14 in which said voids are crevasses hidden by accretion of snow, ice, firn, and any combination thereof.

16. The method of claim 13 in which said alert is selected from the group consisting of:

aural alerts, visual alerts, and a combination thereof.

17. The method of claim 16 in which said aural alert is established by processing scaled signals in parallel to establish the frequency and volume of said aural alert,

wherein said processing of said scaled signals generates an aural tone that intuitively describes the relative distance from said void to an untrained listener.

18. The method of claim 16 in which said visual alert is established by:

subtracting said running average vector processed in said first channel from said vector processed in said second channel;

filtering said result of said subtracting,

wherein said filtering removes spikes that cause speckle;

stacking by m said filtered result to achieve a stacked value,

wherein m is a pre-specified whole number chosen based on experience or experiment;

clipping said stacked value,

wherein said clipping eliminates some amplitude variability that may introduce adverse effects;

peak extracting said clipped stacked value to establish a bin number for said clipped stacked value,

wherein said bin number provides an estimate of distance to a nearest edge of said spatial anomaly;

using said bin number to drive a visual alarm function; and

displaying said visual alarm upon said display mechanism.

19. The method of claim 13 in which detection of voids within a target volume and alerting a person proximate to a display mechanism further comprises:

transforming each said vector to the frequency domain by a Fast FourierTransform;

calculating the standard deviation of all values in each said vector thus transformed;

establishing a trend of relatively steady-state standard deviation calculations resulting from said reflections over a stable cover surface,

wherein as a void is approached and overridden by electromagnetic energy transmitted from said source, said standard deviation trend increases from said steady state level; and

inferring the proximity of said void by observing said increase in said standard deviation.

20. An inexpensive method of detecting and alerting to spatial anomalies within a target volume, said anomalies not otherwise evident without use of methods that are expensive, time-consuming, or both, comprising:

illuminating said target volume with electromagnetic energy from a source placed near a top surface of said volume;

processing reflections of said electromagnetic energy at derived audio frequencies to establish vectors in first and second parallel channels,

wherein a running average of said vectors is maintained in said first channel for comparison to a current vector being processed in said second channel; and

using said comparison to initiate an alert that may be visual, aural, or both,

wherein said visual alert is established by;

subtracting said running average vector processed in said first channel from said vector processed in said second channel;

filtering said result of said subtracting,

wherein said filtering removes spikes that cause speckle;

stacking by m said filtered result to achieve a stacked value,

wherein m is a pre-specified whole number chosen based on experience or experiment;

clipping said stacked value,

wherein said clipping eliminates some amplitude variability that may introduce adverse effects;

peak extracting said clipped stacked value to establish a bin number for said clipped stacked value, wherein said bin number provides an estimate of distance to a nearest edge of said spatial anomaly;

using said bin number to drive a visual alarm function; and

displaying said visual alarm.

21. An inexpensive method of detecting spatial anomalies within a target volume, said anomalies not otherwise evident without use of methods that are expensive, time-consuming, or both, comprising:

illuminating said target volume with electromagnetic energy from a source placed near a top surface of said volume;

placed near a top surface of said volume;

processing reflections of said electromagnetic energy at derived audio

frequencies to establish vectors in first and second parallel channels,

wherein a running average of said vectors is maintained in said first channel for comparison to a current vector being processed in said second channel; and

using said comparison to initiate an alert,

wherein detection of spatial anomalies further comprises;

transforming each said vector to the frequency domain by a Fast Fourier Transform;

calculating the standard deviation of all values in each said vector thus transformed;

establishing a trend of relatively steady-state standard deviation

calculations resulting from said reflections over a stable cover surface,

wherein, as a spatial anomaly is approached and overridden by electromagnetic energy transmitted from said source, said standard deviation trend increases from said steady state level; and

inferring the proximately of said spatial anomaly by observing said increase in said standard deviation.