System for detection of objects with given, known characteristics against a background
First Claim
1. A system for the detection of objects with given, known characteristics against a background, comprising a transmitter means for transmitting one of either electromagnetic or acoustic waves having characteristics adapted for the objects to be detected or correspondingly adapted to suppress the background prior to the detection of the objects, said waves being composed of a number of coherent frequency components whose frequency is a function of time, and a receiver means for receiving backscattered electromagnetic or acoustic waves and for coherent demodulation using signal adaptive filters and comprising more than one homodyne detector, wherein at least one of said transmitter means and said receiver means comprise at least two apertures for coherent transmission or reception of the waves and wherein a distance between said at least two apertures is larger than one wavelength of the transmitted waves, and wherein signals derived from the received waves by said demodulation and filtering, and related to at least two simultaneously transmitted frequencies and at least two apertures respectively, undergo complex multiplication, wherein a signal detected by one of said more than one homodyne detectors at one frequency and at one of said at least two apertures, is subjected to said complex multiplication with another signal detected by another of said more than one homodyne detectors at another simultaneously transmitted frequency at another of said at least two apertures separated from said one aperture by at least one wavelength of said waves, said complex multiplication providing a product which constitutes a matched filter for a given object or background.
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Accused Products
Abstract
The invention is primarily addressed to the problems relating to the detection and identification of vessels against the sea area. A radar sensor connected to powerful data processing equipment can give a monitoring capability having been impossible hitherto, by employing optimal radar structures and signal processing algorithms. There is described which functions which may be operated independently on the transmitter side and the receiver side. Depending upon the purpose such a radar may be applicable for: searching for vessels, searching for wake traces, simultaneous searching for vessels and accompanying wake traces, tracking vessels and wake traces, identifying vessels based upon various filters. As a consequence of the data control such a radar or possibly a corresponding sonar system may be able to reconfigurate as needed, which involves that the requirement for signal processing is reduced and the utilization of the resources improved. In order to form an interference pattern corresponding to the object or objects to be detected, transmitter means and/or receiver means in the system comprise two or more apertures (7A, 7B, 8A, 8B) for the coherent transmission and reception respectively of waves, the mutual distance between these apertures being larger than one wavelength of the waves transmitted.
42 Citations
15 Claims
- 1. A system for the detection of objects with given, known characteristics against a background, comprising a transmitter means for transmitting one of either electromagnetic or acoustic waves having characteristics adapted for the objects to be detected or correspondingly adapted to suppress the background prior to the detection of the objects, said waves being composed of a number of coherent frequency components whose frequency is a function of time, and a receiver means for receiving backscattered electromagnetic or acoustic waves and for coherent demodulation using signal adaptive filters and comprising more than one homodyne detector, wherein at least one of said transmitter means and said receiver means comprise at least two apertures for coherent transmission or reception of the waves and wherein a distance between said at least two apertures is larger than one wavelength of the transmitted waves, and wherein signals derived from the received waves by said demodulation and filtering, and related to at least two simultaneously transmitted frequencies and at least two apertures respectively, undergo complex multiplication, wherein a signal detected by one of said more than one homodyne detectors at one frequency and at one of said at least two apertures, is subjected to said complex multiplication with another signal detected by another of said more than one homodyne detectors at another simultaneously transmitted frequency at another of said at least two apertures separated from said one aperture by at least one wavelength of said waves, said complex multiplication providing a product which constitutes a matched filter for a given object or background.
Specification