Communications: directive radio wave systems and devices (e.g. – Return signal controls radar system – Receiver
Reexamination Certificate
1999-01-05
2001-04-24
Gregory, Bernarr E. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Return signal controls radar system
Receiver
C342S021000, C342S022000, C342S027000, C342S089000, C342S175000, C342S189000, C342S192000, C342S195000
Reexamination Certificate
active
06222481
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
1. The present invention relates to a method of detecting and classifying objects using radar.
Description of the Related Art
2. There are large areas in Asia, Africa, and the Middle East covered with mines. At a rough estimate, 100 million mines are laid in more than 60 countries. Today there does not exist any technology capable of detecting these mines quickly and with large probability. As an example, it has been estimated that with the present pace of clearance 2500 years would be needed to clear Afghanistan of mines.
One problem is all metal fragments surrounding the mines in the ground. For each mine it finds, a metal detector on average also detects a thousand fragments. If the false alarm rate could be reduced to only a hundred per mine, the clearance pace would be increased ten times. Another problem is the non-metallic mines, which are very hard to detect using conventional techniques.
Earlier attempts at classifying detected targets using radar have been concentrated toward air targets. The predominant method has been to compare the amplitude of the returned echo signal for one or more polarizations. The method is aspect dependent, which involves large amounts of data with ensuing handling problems. Systems tend to be either unmanageable or capable of classifying only a small amount of targets or both.
SUMMARY OF THE INVENTION
The present invention solves the problem in question, viz., to be able to classify a large amount of different targets, independently of the aspect angle of the target by designing it as the corresponding stored values of an analysis of possible targets. Convenient realizations of the invention include basing the analysis on the first portion of the returned signal, including the specular reflex, as well as its later portion, including the returned radiation from creeping waves induced in the target and, where appropriate, reflexes from the interior of the target, such as its rear edge. In addition, captured signals may be amplified with increasing amplification according to the distance before they are analyzed, and mines buried in the ground or targets in the atmosphere may be chosen as intended targets.
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International Conference on Ultra-Wideband, Short-Pulse . . . , vol., Apr. 1994, (Brooklyn, USA), H Ling et al, “Time Frequency Processing of Wideband Radar Echo: From Fixed Resolution to Multiresolution and Superresolution”, p. 531, line 15—p. 533, line 19, figure 5, pp. 527-534.
Abrahamson Staffan
Axelsson Dan
Brusmark Bertil
Gustafsson Anders
Strifors Hans
Forsvarets Forskningsanstalt
Gregory Bernarr E.
Jacobson Price Holman & Stern PLLC
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