Communications: directive radio wave systems and devices (e.g. – Transmission through media other than air or free space
Reexamination Certificate
2002-04-05
2003-09-16
Gregory, Bernarr E. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Transmission through media other than air or free space
C342S02500R, C342S027000, C342S118000, C342S145000, C342S146000, C342S147000, C342S158000, C342S175000, C342S176000, C342S179000, C342S190000, C342S191000, C342S195000
Reexamination Certificate
active
06621448
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable
REFERENCE TO A COMPUTER PROGRAM APPENDIX
Not Applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains generally to radar detection systems, and more particularly to a system and method for identifying hidden objects obscured beneath a layer of snow.
2. Description of the Background Art
Detecting objects whose visibility is obscured by accumulated snow has posed a challenge in a number of application areas. Snow removal equipment, such as snow blowers and snowplows, along with other types of vehicles traversing roads or other areas heavily laden with snow, are often subject to collision and damage from guardrails, vehicles, signage, fences, garbage, and other assorted objects hidden by the snow. Other applications exist for detecting objects beneath a layer of snow, such as for use by searchers and law enforcement personnel, which must meet the challenge of finding persons, or objects, which may be buried under one or more accumulated layers of snow. Currently, equipment operators, individuals performing a search, and other individuals subject to activity within snow laden environments have no readily available means of gathering information and images about objects which are otherwise hidden by layers of snow.
Mechanical detectors are conventionally utilized in snow removal equipment for detecting objects, and are an attempt to reduce the amount of damage caused by encounters with obstacles hidden beneath the snow. It will be appreciated that objects buried in the snow may pose a hazard to equipment, such as being ingested by a snow blower when clearing a snow bank. Furthermore, the snow removal equipment may damage items, such as vehicles, the visibility of which is obscured by one or more layers of snow. Detection using a mechanical detector requires a portion of the mechanical detector to make contact with the obstacle, and the technique is not capable of providing an image, or other information, as to the nature of the obstruction, or about those parts of the obstruction which are still hidden beneath the snow. It should be appreciated that the required contact force for such a mechanism is necessarily high so that the unit is not disengaged upon contact with packed snow or icy patches. A high contact force of this nature would often be sufficient to damage trapped vehicles, signage, and so forth. Therefore, mechanical sensing does not provide for the detection of an object prior to contact, and it does not provide imaging of objects hidden beneath the snow. It should also be appreciated that many obstacles typically encountered in a number of applications would not trigger a mechanical detection mechanism, however, they could still represent a significant threat, such as to a moving snowplow vehicle. For example, a number of-smaller objects can be ingested by a rotary plow which may completely entangle the rotary mechanism thereby rendering it inoperative, while requiring extensive time, effort, and expense to repair.
Techniques for detecting individuals buried under avalanches generally utilize forms of cooperative sensing, such as requiring the use of an active transmitter or passive transponder by a buried individual. It will be appreciated that cooperative means are not appropriate when the detection of vehicles, trees, storage containers, snow chains, culvert materials, and other inanimate objects is necessary, or when a priori equipping of an individual with a transmitter is not possible. One proposed non-cooperative technique utilizes at least two, and typically numerous, receiving antennas configured to detect reflected RF energy to determine the direction of the target, however, it is incapable of providing sufficient resolution for imaging obstructions buried in snow.
Techniques are being deployed by the military for obtaining images of the soil by using ground-penetrating radar (GPR). The use of GPR requires transmit/receive antennas which are in contact, or in close proximity, with the ground. Thus, obtaining images using such a system requires the physical relocation of the GPR antenna over the ground area. GPR systems are intended to image objects on or very near the surface of sand or soil, and are not configured for detecting objects within a snow bank, or other accumulation of snow, wherein detecting objects to a depth of about two meters is necessary. It will be further appreciated that the lack of homogeneity within a snow environment presents unique challenges for an object sensing technique. GPR applications generally require complex signal processing to be performed to eliminate unwanted signals and to provide for imaging of the results, as a result of which real-time signal and image processing may not be feasible or cost-effective in these cases. In addition, these GPR systems have been geared toward military applications, such as the detection of unexploded ordinance (UXO). Aside from the aforementioned difficulties, the GPR systems also suffer in the area of system complexity, size, and cost, thereby reducing their applicability such as for civilian transportation applications.
Therefore, a need exists for an apparatus that provides for the detection and imaging of objects obscured beneath a layer of snow which is not subject to the limitations as outlined above. The present invention satisfies those needs, as well as others, and overcomes the deficiencies of previously developed solutions.
BRIEF SUMMARY OF THE INVENTION
The present invention is a non-contact system and method for detecting and/or imaging of objects which are obscured beneath snow, or materials of similar composition. The snow penetrating radar system and method presented herein is applicable to a number of applications and is particularly well-suited for search and rescue situations, and for the prevention of damage to machines operating in snow, such as snow removal equipment. The-system maybe implemented as a compact low-cost unit that may be mounted upon a-movable platform, such as a motor vehicle, aircraft (i.e. helicopters), or a mobile individual (i.e. person on foot or on horseback). By utilizing the present invention on snow removal equipment, collisions with objects hidden beneath the snow may be prevented, and the damage resulting from the ingestion of small objects into the blade mechanism of rotary snowplows, (“blowers”) can be circumvented. The ability to reconstruct object images for identifying objects obscured by snow allows-for the rapid scanning of a snow scene, for example an avalanche site, from several meters above the scene while detecting, locating, and possible victims. The ability to discern victims from debris can facilitate victim rescue operations in snow-laden areas.
The method utilized within the invention for detecting objects beneath a layer of snow is conceptually similar to the ground-penetrating radar utilized by the military. However, the system and method of the present invention does not require the physical movement of an antenna over ground areas to be imaged, and is capable of imaging obscured objects without the need of pulsed radar phase measurements in combination with expensive and complicated digital signal image processing techniques to reconstruct an object image. The present system and method is configured to reconstruct real-time multiple frames per second non-specular object images without making contact with the objects and regardless of the condition of the overlying snow, such as powder, packed snow, very dense snow, dry snow, wet snow, and combinations thereof.
Imaging through snow with the present system allows scanning of a scene in from one to three dimensions, with the preferred use of two dimensions such as azimuth and elevation. The radar utilized herein provides a continuous wave output in preference to the conventional pulsed radar systems which provide imaging through the registration of phase differences. Objects may be registered from several meters distance while providing sufficient resolution to detect objects which could po
Lasky Ty A.
Ravani Bahram
Shahrdad Tabib
Gregory Bernarr E.
O'Banion John P.
The Regents of the University of California
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