WO2005054892A1 - Target detecting method - Google Patents

Target detecting method Download PDF

Info

Publication number
WO2005054892A1
WO2005054892A1 PCT/EP2004/011190 EP2004011190W WO2005054892A1 WO 2005054892 A1 WO2005054892 A1 WO 2005054892A1 EP 2004011190 W EP2004011190 W EP 2004011190W WO 2005054892 A1 WO2005054892 A1 WO 2005054892A1
Authority
WO
WIPO (PCT)
Prior art keywords
target
dimension
value
structural
received signal
Prior art date
Application number
PCT/EP2004/011190
Other languages
German (de)
French (fr)
Inventor
Dirk Neumeister
Original Assignee
Atlas Elektronik Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Atlas Elektronik Gmbh filed Critical Atlas Elektronik Gmbh
Publication of WO2005054892A1 publication Critical patent/WO2005054892A1/en

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
    • G01S15/006—Theoretical aspects
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
    • G01S3/80—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using ultrasonic, sonic or infrasonic waves
    • G01S3/86—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using ultrasonic, sonic or infrasonic waves with means for eliminating undesired waves, e.g. disturbing noises
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
    • G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves

Definitions

  • the invention relates to a method for detecting targets of the type defined in the preamble of claim 1.
  • a number of methods for the so-called passive detection of targets are known in waterborne sound technology, which emit sound waves due to their driving noise or actively emit them as sound impulses. All of these methods are based on the basic principle of recognizing in the electrical output or received signals of the receiver a useful signal superimposed by an interference noise which is picked up by a receiver which has a large number of electroacoustic transducers and which is remote from the target.
  • the level increase of a broadband received signal or a demodulated noise band in the received signal is used by means of energy detection, as is given, for example, in DE 35 31 230 AI.
  • the useful signal radiated from the target can also be detected with an edge detector which evaluates the pulse increase of a transmission pulse radiated from the target, as is known from DE 197 45 726 C1.
  • a useful signal emitted by the target can also be determined by transient detection. The recognition of such a useful signal is made more difficult by the fact that the sound emission of potential targets is continuously reduced.
  • Radiated goals transmit pulses for measuring distance or for communication are also correspondingly skillful modulation of the sound waves off the general noise background increasingly difficult to detect, "" "so that the betrayal probability of a target always less is.
  • the detection of targets with a transmitter and receiver having a location system by receiving a location pulse reflected by the target at large target distances is changing
  • Transmission properties of the transmission medium are also extremely difficult, even if correlation methods adapted to the locating pulse are used. These problems are described in DE-OS 197 36 552. However, they require knowledge of the properties of the transmission medium.
  • the invention is based on the object of specifying a method that reliably detects quiet, low-noise, low-wave energy-emitting targets or targets that emit or reflect signals hidden in the noise, and thereby requires no knowledge of the properties of the transmission medium.
  • the method according to the invention has the advantage that the useful signal contained in the received signal is not used or sought for target detection, but rather the structure of the waves emitted by the target and propagating in the transmission medium is used, which also includes the received signal is immanent. Although this structure cannot be recognized in the course of the received signal over time, it can be deduced by a chaos-theoretical structure analysis. Since all waves emitted by a target in whatever manner and which represent the temporal course of an oscillation have a structure that deviates from the stochastic noise, be it an ordered or disordered, or at least a deterministic-chaotic structure, this can be recognized by recognizing this structure in the received signal Filter the target out of the background noise and use it to detect.
  • the method according to the invention is also robust against changes in the transmission medium during its use. Any received signal that is above the amplifier's own noise can be used for detection without having to register an increase in level, so that the range depends solely on the sensitivity of the receiver.
  • parts of the received signal reflected at a target can be recognized without a pattern comparison with the transmitted signal and lead to the detection of the target and its location.
  • the method according to the invention is preferably used in waterborne sound engineering or underwater acoustics, but can also be used for the detection of targets which emit acoustic or electromagnetic waves in the transmission medium air.
  • data is reduced over the course of the received signal by mapping the received signal into a multidimensional phase space.
  • the advantage is that a structure contained in the received signal can be accessed particularly easily by mapping a structure analysis and evaluation. This is because the image only provides an absolute irregularity and is therefore unstructured if the received signal has only statistical noise and no target noise.
  • Driving noises which have a periodic portion, or emitted modulated waves, which are also subject to a law, leave a structure in the image as target noises and lead to the detection of the target.
  • a return map is selected according to an advantageous embodiment of the invention, in that a value of a selected property of the received signal taken from the time profile of the received signal is plotted above its previous value.
  • This figure shows a structure due to the determinism to which the wave-emitting target is subjected.
  • the values of the lower or upper vertices or reversal points of the received signal, the temporal spacing of the vertices or the temporal spacing of identical instantaneous values in the received signal are suitable as properties of the received signal for the re-imaging.
  • the instantaneous values which are shifted from one another by the same time intervals, or the time intervals of the puncture points of a Poincare- Section, in which a plane is placed in any orientation with respect to the time axis by the received signal.
  • a structural dimension is determined for evaluating the structure of the image and only recognized for the target and the target detection is displayed when the specific value of the structural dimension lies within a predetermined range of the structural dimension.
  • a fractal dimension is calculated as the structural dimension and the maximum permissible value of the fractal dimension is determined for target recognition in accordance with a desired false alarm rate. If the calculated value of the fractal dimension lies between zero and the specified maximum value, the target is recognized.
  • 1 is a block diagram to illustrate the method for target detection
  • FIG. 3 is a diagram for explaining the function block "re-mapping" in the block diagram of FIG. 1, 4 shows two diagrams for explaining the function and 5 of the "fractal dimension" function block in the block diagram of FIG. 1.
  • an electroacoustic receiving antenna 10 is used, which is arranged away from sound-emitting targets in the water.
  • Sound-radiating targets are understood to mean targets which both generate and emit sound themselves, for example through drive units or active location, and also only reflect sound.
  • a so-called linear antenna is used, which has a multiplicity of electro-acoustic transducers or hydrophones 11 which are aligned equidistantly.
  • Such a linear antenna is known as a tow antenna (towed array) or as a side antenna attached to the hull (flank array), sometimes also referred to as a side streamer.
  • All hydrophones 11 are operated together, and by appropriate signal processing of all output signals of the hydrophones 11 in a so-called directional generator 12 or beamformer, a directional characteristic of the receiving antenna 10 is formed, the axis of greatest acoustic reception sensitivity is perpendicular to the receiving antenna 10 or at an acute angle - 90 ° ⁇ ⁇ + 90 ° to the normal of the receiving antenna can be pivoted.
  • the structure and mode of operation of the direction generator 12 is known and is described, for example, in US Pat. No. 4,060,792 or DE 21 14 373 AI or in DE 100 27 538 AI.
  • An arbitrarily assumed example of a reception signal or the group signal of the reception antenna 10 present at the output of the directional generator 12 is shown in FIG. 2.
  • the instantaneous value of the group signal is shown there over time.
  • the group signal formed from the output signals of the individual hydrophones 11 is subsequently subjected to a chaos-theoretical structural analysis.
  • the group signal is mapped in function block 13 into a multidimensional phase space
  • a mapping is carried out in a two-dimensional phase space with the aid of a so-called “back map.”
  • a value of a selected property of the group signal taken from the temporal course of the group signal is plotted against the previous value The lower vertices of the group signal are used as the selected property.
  • the upper vertices or the time interval between the vertices or instantaneous values taken at the same time intervals can also be used. to use the time intervals of the puncture points of a P.oincare cut as the selected property.
  • the Poincare cut reference is made to Crighton Dowling "Modern Methods in Analytical Acoustics", Springer-Verlag London Ltd., 1992, page 698 ff. in which the lower peak values ⁇ n eu taken from the group signal in FIG. 2 are plotted on the ordinate and the preliminary values of the lower peak values ( ⁇ ait ) taken from the group signal in FIG. 2 are plotted on the abscissa. It can clearly be seen that the Mapping of the group signal a significant data reduction has taken place, in which a deterministic structure, which originates from a sound-emitting target, can be recognized.
  • the structure of the mapping of the group signal generated in function block 13 is evaluated in function block 14.
  • a measure is calculated for the structure, hereinafter called the structural measure.
  • the so-called fractal dimension d F is selected as the structural dimension.
  • Calculation methods for the fractal dimension d F are the lattice method (GV), the distance analysis method (AV) and the enlargement method (VV).
  • GV lattice method
  • AV distance analysis method
  • VV enlargement method
  • the grid method is used to calculate the fractal dimension d F of the structure of the re-mapping of the group signal shown in FIG. 3.
  • This grid method uses a systematic grid covering of the image by squares with the side length ⁇ . The side length ⁇ is increasingly reduced and the number N of squares is determined in each case . that are hit by the picture. Such a grid coverage of the figure is shown in FIG. 4. If ⁇ is systematically reduced, starting from a relatively large value, there is a relationship N ( ⁇ ) between the number N of the squares hit and the side length ⁇ . If N ( ⁇ ) is plotted double logarithmically over 1 / ⁇ , the result is a straight line whose slope is an approximation for the fractal dimension d F. o r> * ->
  • the value of the fractal dimension d F is present at the output of the function block 14 and can be used to trigger a display for the target detection in a display unit 15.
  • the output signal of the function block 14 that is to say the value of the fractal dimension d F , is fed to a comparator 16, which in turn is connected to an adjuster 17 for the false alarm rate.
  • the maximum permissible value of the fractal dimension d ⁇ ax which can be chosen between 0 and 2, is specified in the adjuster 17.
  • the value "0" of the fractal dimension results from the re-mapping of a purely harmonic group signal, for example a consine or sine wave, while the value "2" is the structural measure of the mapping of a purely chaotic signal.
  • the structural analysis therefore only gives an indication of a possibly existing target if the value of the fractal dimension is 0 ⁇ d ⁇ ax ⁇ 2.
  • the predetermined maximum value of the fractal dimension d m & x is now compared in the comparator 16 with the value of the fractal dimension d F calculated in the function block 14. The latter is smaller as the maximum predetermined value d ⁇ a, the comparator 16 generates an output signal which triggers the display for a detected target in the display unit 15.
  • the directional angle ⁇ can be shown in the display unit 15, which angle has been removed by the directional generator 12 and fed to the display unit 15.
  • a gate 18 is opened by the output signal of the comparator 16, at which the swivel angle ⁇ currently set by the direction generator 12 is applied, at which the respective group signal is formed in the direction generator 12.

Abstract

The invention relates to a method for detecting targets emitting waves of signals received from a receiver remote from the target in an environmental communications medium. The aim of said invention is to reliably detect the targets, on the assumption that the properties of said communications medium are unknown, even for low-energy targets or targets emitting noise-disturbed signals. For this purpose, said invention is characterised in that the received signals are exposed to a structural analysis based on a chaos theory. The localisation of at least one chaos deterministic structure makes it possible to detect a target and to control the target detection by structure evaluation.

Description

A T L A S E L E K T R O N I K G m b H Bremen A T L A S E L E K T R O N I K G m b H Bremen
'VERFAHREN ZUM DETEKTIEREN VON ZIELEN '' METHOD FOR DETECTING TARGETS
Die Erfindung betrifft ein Verfahren zum Detektieren von Zielen der im Oberbegriff des Anspruchs 1 definierten Gattung.The invention relates to a method for detecting targets of the type defined in the preamble of claim 1.
In der Wasserschalltechnik sind eine Reihe von Verfahren zur sog. passiven Detektion von Zielen, z.B. Überwasserschiffen, U-Booten oder Torpedos, bekannt, die Schallwellen aufgrund ihrer Fahrgeräusche abstrahlen oder als Schallimpulse aktiv aussenden. Alle diese Verfahren beruhen auf dem Grundprinzip, ein von einem Störgeräusch überlagertes Nutzsignal, das von einem eine Vielzahl von elektroakustischen Wandlern aufweisenden, zielfernen Empfänger abgenommen wird, in den elektrischen Ausgangs- oder Empfangssignalen des Empfängers zu erkennen. Als Beispiel wird der Pegelanstieg eines breitbandigen Empfangssignals oder eines demodulierten Rauschbandes im Empfangssignal mittels Energiedetektion herangezogen, wie es beispielsweise in der DE 35 31 230 AI angegeben ist. Das vom Ziel abgestrahlte Nutzsignal kann außer mit einem Energiedetektor auch mit einem Flankendetektor erkannt werden, der den Impulsanstieg eines vom Ziel abgestrahlten Sendeimpulses auswertet, wie es aus der DE 197 45 726 Cl bekannt ist. Auch durch Transientendetektion kann ein vom Ziel abgestrahltes Nutzsignal ermittelt werden. Das Erkennen eines solchen Nutzsignals wird dadurch erschwert, dass die Schallemission potentieller Ziele laufend gesenkt wird. Von Zielen abgestrahlte Sendeimpulse zur Entfernungsmessung oder zur Kommunikation sind auch durch entsprechend geschickte Modulation der Schallwellen aus- dem allgemeinen Störhintergrund zunehmend schwieriger zu detektieren, """so dass die Verratwahrscheinlichkeit eines Ziels immer geringer wird. Die Detektion von Zielen mit einer einen Sender und Empfänger aufweisenden Ortungsanlage durch den Empfang eines vom Ziel reflektierten Ortungsimpulses bei großen Zieldistanzen ist bei wechselndenA number of methods for the so-called passive detection of targets, for example surface ships, submarines or torpedoes, are known in waterborne sound technology, which emit sound waves due to their driving noise or actively emit them as sound impulses. All of these methods are based on the basic principle of recognizing in the electrical output or received signals of the receiver a useful signal superimposed by an interference noise which is picked up by a receiver which has a large number of electroacoustic transducers and which is remote from the target. As an example, the level increase of a broadband received signal or a demodulated noise band in the received signal is used by means of energy detection, as is given, for example, in DE 35 31 230 AI. In addition to an energy detector, the useful signal radiated from the target can also be detected with an edge detector which evaluates the pulse increase of a transmission pulse radiated from the target, as is known from DE 197 45 726 C1. A useful signal emitted by the target can also be determined by transient detection. The recognition of such a useful signal is made more difficult by the fact that the sound emission of potential targets is continuously reduced. Radiated goals transmit pulses for measuring distance or for communication are also correspondingly skillful modulation of the sound waves off the general noise background increasingly difficult to detect, "" "so that the betrayal probability of a target always less is. The detection of targets with a transmitter and receiver having a location system by receiving a location pulse reflected by the target at large target distances is changing
Übertragungseigenschaften des Übertragungsmediums ebenfalls außerordentlich schwierig, auch wenn an den Ortungsimpuls angepasste Korrelationsverfahren verwendet werden. Diese Probleme sind in der DE-OS 197 36 552 beschrieben. Sie setzen aber eine Kenntnis über die Eigenschaften des Übertragungsmediums voraus.Transmission properties of the transmission medium are also extremely difficult, even if correlation methods adapted to the locating pulse are used. These problems are described in DE-OS 197 36 552. However, they require knowledge of the properties of the transmission medium.
Der Erfindung liegt die Aufgabe zugrunde, ein Verfahren anzugeben, das leise, geräuscharme, wenig Wellenenergie abstrahlende Ziele oder Ziele, die im Rauschen versteckte Signale aussenden oder reflektieren, zuverlässig detektiert und dabei keine Kenntnis über die Eigenschaften des Übertragungsmediums erfordert.The invention is based on the object of specifying a method that reliably detects quiet, low-noise, low-wave energy-emitting targets or targets that emit or reflect signals hidden in the noise, and thereby requires no knowledge of the properties of the transmission medium.
Die Aufgabe wird erfindungsgemäß durch die Merkmale im Anspruch 1 gelöst.The object is achieved by the features in claim 1.
Das erfindungsgemäße Verfahren hat den Vorteil, dass nicht das im Empfangssignal enthaltene Nutzsignal zur Zieldetektion herangezogen oder gesucht wird, sondern die Struktur der vom Ziel abgestrahlten und im Übertragungsmedium sich ausbreitenden Wellen genutzt wird, die auch dem Empfangsignal immanent ist. Diese Struktur ist im zeitlichen Verlauf des Empfangssignals zwar selbst nicht erkennbar, läßt sich aber durch eine chaostheoretische Strukturanalyse herausschälen. Da alle von einem Ziel wie immer geartet abgestrahlten Wellen, die den zeitlichen Verlauf einer Schwingung darstellen, eine vom stochastischen Rauschen abweichende, sei es eine geordnete oder ungeordnete, zumindest aber eine deterministisch-chaotische Struktur aufweisen, läßt sich durch Erkennen dieser Struktur im Empfangssignal das Ziel aus dem Hintergrundrauschen herausfiltern und damit detektieren. Da diese Struktur durch Umwelteinflüsse nicht verlorengeht, ist das erfindungsgemäße Verfahren auch robust gegen Veränderungen im Übertragungsmedium während seines Einsatzes. Jedes Empfangssignal, das über dem eigenen Verstärkerrauschen liegt, kann zur Detektion herangezogen werden, ohne dass ein Pegelanstieg verzeichnet werden muß, so dass die Reichweite allein von der Empfindlichkeit des Empfängers abhängt. Bei Einsatz in einer Ortungsanlage, bei der Ortungsimpulse ausgesendet werden, sind an einem Ziel reflektierte Anteile im Empfangssignal ohne Mustervergleich mit dem ausgesendeten Signal erkennbar und führen zur Detektion des Ziels und seiner Ortsbestimmung.The method according to the invention has the advantage that the useful signal contained in the received signal is not used or sought for target detection, but rather the structure of the waves emitted by the target and propagating in the transmission medium is used, which also includes the received signal is immanent. Although this structure cannot be recognized in the course of the received signal over time, it can be deduced by a chaos-theoretical structure analysis. Since all waves emitted by a target in whatever manner and which represent the temporal course of an oscillation have a structure that deviates from the stochastic noise, be it an ordered or disordered, or at least a deterministic-chaotic structure, this can be recognized by recognizing this structure in the received signal Filter the target out of the background noise and use it to detect. Since this structure is not lost due to environmental influences, the method according to the invention is also robust against changes in the transmission medium during its use. Any received signal that is above the amplifier's own noise can be used for detection without having to register an increase in level, so that the range depends solely on the sensitivity of the receiver. When used in a location system in which location pulses are emitted, parts of the received signal reflected at a target can be recognized without a pattern comparison with the transmitted signal and lead to the detection of the target and its location.
Das erfindungsgemäße Verfahren wird bevorzugt in der Wasserschalltechnik oder Unterwasserakustik eingesetzt, kann aber auch zur Detektion von Zielen, die im Übertragungsmedium Luft akustische oder elektromagnetische Wellen aussenden, verwendet werden.The method according to the invention is preferably used in waterborne sound engineering or underwater acoustics, but can also be used for the detection of targets which emit acoustic or electromagnetic waves in the transmission medium air.
Zweckmäßige Ausführungsformen des erfindungsgemäßen Verfahrens mit vorteilhaften Weiterbildungen und Ausgestaltungen der Erfindung ergeben sich aus den weiteren Ansprüchen. Gemäß einer vorteilhaften Ausführungsform der Erfindung wird für die Strukturanalyse eine Datenreduktion im zeitlichen Verlauf des Empfangssignals vorgenommen, indem das Empfangssignal in einen mehrdimensionalen Phasenraum abgebildet wird. Der Vorteil besteht darin, dass eine im Empfangssignal enthaltene Struktur durch die Abbildung einer Strukturanalyse und Bewertung besonders einfach zugänglich wird. Die Abbildung liefert nämlich nur dann eine absolute Ungesetzmäßigkeit und ist damit unstrukturiert, wenn das Empfangssignal lediglich statistisches Rauschen und kein Zielgeräusch aufweist. Fahrgeräusche, die einen periodischen Anteil aufweisen, oder ausgesendete modulierte Wellen, die ebenfalls einer Gesetzmäßigkeit unterliegen, hinterlassen als Zielgeräusche eine Struktur in der Abbildung und führen zur Detektion des Ziels.Expedient embodiments of the method according to the invention with advantageous developments and refinements of the invention result from the further claims. According to an advantageous embodiment of the invention, for the structural analysis, data is reduced over the course of the received signal by mapping the received signal into a multidimensional phase space. The advantage is that a structure contained in the received signal can be accessed particularly easily by mapping a structure analysis and evaluation. This is because the image only provides an absolute irregularity and is therefore unstructured if the received signal has only statistical noise and no target noise. Driving noises, which have a periodic portion, or emitted modulated waves, which are also subject to a law, leave a structure in the image as target noises and lead to the detection of the target.
Für die Abbildung des Empfangssignals in einen zweidimensionalen Phasenraum wird gemäß einer vorteilhaften Ausführungsform der Erfindung eine Rückabbildung (Return-Map) gewählt, indem jeweils ein aus dem zeitlichen Verlauf des Empfangssignals entnommener Wert einer ausgewählten Eigenschaft des Empfangssignals über seinem Vorwert aufgetragen wird. Diese Abbildung zeigt infolge des Determinismus, dem das .wellenabstrahlende Ziel unterworfen ist, eine Struktur. Für die Rückabbildung eignen sich als Eigenschaft des Empfangssignals die Werte der unteren oder oberen Scheitel- oder Umkehrpunkte des Empfangssignals, der zeitliche Abstand der Scheitelpunkte oder der zeitliche Abstand gleicher Momentanwerte im Empfangssignal. Ebenso geeignet sind die Momentanwerte, die um gleiche Zeitintervalle gegeneinander verschoben sind, oder die zeitlichen Abstände der Durchstoßpunkte eines Poincare- Schnitts, bei dem eine Ebene in beliebiger Ausrichtung gegenüber der Zeitachse durch das Empfangssignal gelegt wird.For mapping the received signal into a two-dimensional phase space, a return map (return map) is selected according to an advantageous embodiment of the invention, in that a value of a selected property of the received signal taken from the time profile of the received signal is plotted above its previous value. This figure shows a structure due to the determinism to which the wave-emitting target is subjected. The values of the lower or upper vertices or reversal points of the received signal, the temporal spacing of the vertices or the temporal spacing of identical instantaneous values in the received signal are suitable as properties of the received signal for the re-imaging. The instantaneous values, which are shifted from one another by the same time intervals, or the time intervals of the puncture points of a Poincare- Section, in which a plane is placed in any orientation with respect to the time axis by the received signal.
Um die Falschalarmrate bei der Zieldetektion einzuschränken, wird zur Bewertung der Struktur der Abbildung ein Strukturmaß bestimmt und erst dann auf Ziel erkannt und die Zieldetektion angezeigt, wenn der bestimmte Wert des Strukturmaßes innerhalb eines vorgegebenen Bereichs des Strukturmaßes liegt .In order to limit the false alarm rate in the target detection, a structural dimension is determined for evaluating the structure of the image and only recognized for the target and the target detection is displayed when the specific value of the structural dimension lies within a predetermined range of the structural dimension.
Gemäß einer bevorzugten Ausführungsform der Erfindung wird als Strukturmaß eine fraktale Dimension berechnet und der maximal zugelassene Wert der fraktalen Dimension für eine Zielerkennung entsprechend einer gewünschten Falschalarmrate festgelegt. Liegt der berechnete Wert der fraktalen Dimension zwischen Null und dem vorgegebenen Maximalwert, wird auf Ziel erkannt.According to a preferred embodiment of the invention, a fractal dimension is calculated as the structural dimension and the maximum permissible value of the fractal dimension is determined for target recognition in accordance with a desired false alarm rate. If the calculated value of the fractal dimension lies between zero and the specified maximum value, the target is recognized.
Die Erfindung ist anhand eines in der Zeichnung illustrierten Ausführungsbeispiels im folgenden näher beschrieben. Es zeigen:The invention is described below with reference to an embodiment illustrated in the drawing. Show it:
Fig. 1 ein Blockschaltbild zur Illustrierung des Verfahrens zur Zieldetektion,1 is a block diagram to illustrate the method for target detection,
Fig. 2 eine grafische Darstellung eines willkürlich angenommen, am Ausgang des Richtungsbildners anstehenden Gruppensignals,2 shows a graphical representation of an arbitrarily assumed group signal present at the output of the direction generator,
Fig. 3 ein Diagramm zur Erläuterung des Funktionsblocks "Rückabbildung" im Blockschaltbild der Fig. 1, Fig. 4 zwei Diagramme zur Erläuterung der Funktion und 5 des Funktionsblocks "fraktale Dimension" im Blockschaltbild der Fig. 1.3 is a diagram for explaining the function block "re-mapping" in the block diagram of FIG. 1, 4 shows two diagrams for explaining the function and 5 of the "fractal dimension" function block in the block diagram of FIG. 1.
Bei dem nachfolgend beschriebenen Verfahren zur Zieldetektion, mit dem sowohl schallabstrahlende Ziele aufgefaßt al*s auch die Peilrichtung zu den einzelnen Zielen bestimmt werden kann, wird eine elektroakustische Empfangsantenne 10 verwendet, die entfernt von schallabstrahlenden Zielen im Wasser angeordnet ist. Unter schallabstrahlenden Zielen werden solche Ziele verstanden, die sowohl selbst Schall erzeugen und aussenden, z.B. durch Antriebsaggregate oder Aktivortung, als auch nur Schall reflektieren. Im Ausführungsbeispiel der Fig. 1 ist eine sog. Linearantenne eingesetzt, die eine Vielzahl von äquidistant aufgereihten elektroakustischen Wandlern oder Hydrofonen 11 aufweist. Eine solche Linearantenne ist als Schleppantenne (towed-array) oder als eine am Bootskörper befestigte Seitenantenne (flank-array) , mitunter auch als Bordwandstreamer bezeichnet, bekannt. Alle Hydrofone 11 werden gemeinsam betrieben, und durch eine entsprechende Signalverarbeitung aller Ausgangssignale der Hydrofone 11 in einem sog. Richtungsbildner 12 oder Beamformer wird eine Richtcharakteristik der Empfangsantenne 10 gebildet, deren Achse größter akustischer Empfangsempfindlichkeit rechtwinklig auf der Empfangsantenne 10 steht oder unter einem spitzen Winkel -90°<θ<+90° zur Normalen der Empfangsantenne geschwenkt sein kann. Aufbau und Wirkungsweise des Richtungsbildners 12 ist bekannt und beispielsweise in der US 4 060 792 oder der DE 21 14 373 AI oder in der DE 100 27 538 AI beschrieben. Ein willkürlich angenommenes Beispiel für ein am Ausgang des Richtungsbildners 12 anstehendes Empfangs- oder der Gruppensignal der Empfangsantenne 10, ist in Fig. 2 dargestellt. Dort ist der Momentanwert des Gruppensignals über der Zeit dargestellt. Um in einem solchen Gruppensignal ein evtl. vorhandenes, schallabstrahlendes Ziel zu erkennen, wird das aus "dem Ausgangssignalen der einzelnen Hydrofone 11 gebildete Gruppensignal nachfolgend einer chaostheroretischen Strukturanalyse unterzogen. Hierzu wird in dem Funktionsblock 13 eine Abbildung des Gruppensignals in einen mehrdimensionalen Phasenraum vorgenommen. Im Ausführungsbeispiel erfolgt eine Abbildung in einen zweidimensionalen Phasenraum mit Hilfe einer sog. Rückabbildung (Return-Map) . Hierzu wird ein aus dem zeitlichen Verlauf des Gruppensignals entnommener Wert einer ausgewählten Eigenschaft des Gruppensignals über den Vorwert aufgetragen. Wie in Fig. 2 illustriert ist werden beispielsweise als ausgewählte Eigenschaft die unteren Scheitelpunkte des Gruppensignals verwendet. Es können jedoch auch die oberen Scheitelpunkte oder der zeitliche Abstand der Scheitelpunkte oder in gleichen Zeitintervallen abgenommene Momentanwerte herangezogen werden. Auch ist es möglich, als ausgewählte Eigenschaft die zeitlichen Abstände der Durchstoßpunkte eines P.oincare-Schnitts zu verwenden. Zum Poincare-Schnitt wird verwiesen auf Crighton Dowling "Modern Methodes in Analytical Acoustics", Springer-Verlag London Ltd., 1992, Seite 698 ff.. Die so durchgeführte Rückabbildung des Gruppensignals in den zweidimensionalen Phasenraum ist im Diagramm der Fig. 3 dargestellt, in dem auf der Ordinate die dem Gruppensignal in Fig. 2 entnommenen unteren Scheitelwerte αneu und auf der Abszisse die dem Gruppensignal in Fig. 2 entnommenen Vorwerte der unteren Scheitelwerte (αait) aufgetragen sind. Deutlich ist zu sehen, dass durch die Abbildung des Gruppensignals eine wesentliche Datenreduktion erfolgt ist, in der eine deterministische Struktur, die von einem schallabstrahlenden Ziel herrührt, erkannt werden kann.In the method for target detection described below, with which both sound-emitting targets and the direction of sight to the individual targets can be determined, an electroacoustic receiving antenna 10 is used, which is arranged away from sound-emitting targets in the water. Sound-radiating targets are understood to mean targets which both generate and emit sound themselves, for example through drive units or active location, and also only reflect sound. In the exemplary embodiment in FIG. 1, a so-called linear antenna is used, which has a multiplicity of electro-acoustic transducers or hydrophones 11 which are aligned equidistantly. Such a linear antenna is known as a tow antenna (towed array) or as a side antenna attached to the hull (flank array), sometimes also referred to as a side streamer. All hydrophones 11 are operated together, and by appropriate signal processing of all output signals of the hydrophones 11 in a so-called directional generator 12 or beamformer, a directional characteristic of the receiving antenna 10 is formed, the axis of greatest acoustic reception sensitivity is perpendicular to the receiving antenna 10 or at an acute angle - 90 ° <θ <+ 90 ° to the normal of the receiving antenna can be pivoted. The structure and mode of operation of the direction generator 12 is known and is described, for example, in US Pat. No. 4,060,792 or DE 21 14 373 AI or in DE 100 27 538 AI. An arbitrarily assumed example of a reception signal or the group signal of the reception antenna 10 present at the output of the directional generator 12 is shown in FIG. 2. The instantaneous value of the group signal is shown there over time. In order to identify a possibly existing, sound-emitting target in such a group signal, the group signal formed from the output signals of the individual hydrophones 11 is subsequently subjected to a chaos-theoretical structural analysis. For this purpose, the group signal is mapped in function block 13 into a multidimensional phase space In the exemplary embodiment, a mapping is carried out in a two-dimensional phase space with the aid of a so-called “back map.” For this purpose, a value of a selected property of the group signal taken from the temporal course of the group signal is plotted against the previous value The lower vertices of the group signal are used as the selected property. However, the upper vertices or the time interval between the vertices or instantaneous values taken at the same time intervals can also be used. to use the time intervals of the puncture points of a P.oincare cut as the selected property. Regarding the Poincare cut, reference is made to Crighton Dowling "Modern Methods in Analytical Acoustics", Springer-Verlag London Ltd., 1992, page 698 ff. in which the lower peak values α n eu taken from the group signal in FIG. 2 are plotted on the ordinate and the preliminary values of the lower peak values (α ait ) taken from the group signal in FIG. 2 are plotted on the abscissa. It can clearly be seen that the Mapping of the group signal a significant data reduction has taken place, in which a deterministic structure, which originates from a sound-emitting target, can be recognized.
Die Struktur der im Funktionsblock 13 erzeugten Abbildung des Gruppensignals wird im Funktionsblock 14 bewertet. Hierzu wird ein Maß^--ur die Struktur, im folgenden Strukturmaß genannt, berechnet. Im Ausführungsbeispiel ist als Strukturmaß die sog. fraktale Dimension dF gewählt. Zum Begriff und der Berechnung der fraktalen Dimension wird verwiesen auf Edward Ott, "Chaos in Dynamical Systems", Cambridge University Press 1993, Seite 69 ff. oder Dr. Roman Worg "Deterministisches Chaos", Bibliographisches Institut & F.A. Brockhaus AG, 1993, Seite 125 ff. Berechnungsverfahren für die fraktale Dimension dF sind das Gitterverfahren (GV) , das Abstandsanalyse-Verfahren (AV) und das Vergrößerungs- Vermehrungsverfahren (VV) . Im Ausführungsbeispiel der Fig. 1 wird zur Berechnung der fraktalen Dimension dF der in Fig. 3 wiedergegebenen Struktur der Rückabbildung des Gruppensignals das Gitterverfahren verwendet. Bei diesem Gitterverfahren bedient man sich einer systematischen Gitterüberdeckung der Abbildung durch Quadrate mit der Seitenlänge ε. Dabei wird zunehmend die Seitenlänge ε verkleinert und jeweils die Anzahl N der Quadrate bestimmt., die von der Abbildung getroffen werden. Eine solche Gitter-Überdeckung der Abbildung ist in Fig. 4 dargestellt. Wird ε, ausgehend von einem relativ großen Wert, systematisch verkleinert, so ergibt sich zwischen der Anzahl N der getroffenen Quadrate und der Seitenlänge ε ein Zusammenhang N(ε). Trägt man N(ε) über 1/ε doppeltlogarithmisch auf, so ergibt sich eine Gerade, deren Steigung eine Näherung für die fraktale Dimension dFist. o r> *->The structure of the mapping of the group signal generated in function block 13 is evaluated in function block 14. For this purpose, a measure is calculated for the structure, hereinafter called the structural measure. In the exemplary embodiment, the so-called fractal dimension d F is selected as the structural dimension. For the term and the calculation of the fractal dimension, reference is made to Edward Ott, "Chaos in Dynamical Systems", Cambridge University Press 1993, page 69 ff. Or Dr. Roman Worg "Deterministic Chaos", Bibliographisches Institut & FA Brockhaus AG, 1993, page 125 ff. Calculation methods for the fractal dimension d F are the lattice method (GV), the distance analysis method (AV) and the enlargement method (VV). In the exemplary embodiment in FIG. 1, the grid method is used to calculate the fractal dimension d F of the structure of the re-mapping of the group signal shown in FIG. 3. This grid method uses a systematic grid covering of the image by squares with the side length ε. The side length ε is increasingly reduced and the number N of squares is determined in each case . that are hit by the picture. Such a grid coverage of the figure is shown in FIG. 4. If ε is systematically reduced, starting from a relatively large value, there is a relationship N (ε) between the number N of the squares hit and the side length ε. If N (ε) is plotted double logarithmically over 1 / ε, the result is a straight line whose slope is an approximation for the fractal dimension d F. o r> * ->
In Fig. 5 ist eine solche Gerade dargestellt, die beispielhaft die Steigung von 1,36 aufweist. Da die Rückabbildung eines rein stochastischen Signals ohne jegliche deterministische Struktur eine fraktale Dimension dF = 2 ergibt, ist das Steigungsmaß 1,36 ein Indiz dafür, dass in dem Gruppensignal eine deterministische Struktur enthalten ist, die durch Schallabstrahlung von einem Ziel verursacht ist. Damit ist das Ziel detektiert, und durch den Schwenkwinkel θ der Richtcharakteristik der Empfangsantenne 10, mit dem das Gruppensignal empfangen worden ist, ist die Zielpeilung gegeben. Der Wert der fraktalen Dimension dF liegt am Ausgang des Funktionsblocks 14 an und kann zur Auslösung einer Anzeige für die Zieldetektion in einer Anzeigeinheit 15 herangezogen werden.Such a straight line is shown in FIG. 5, which has, for example, the slope of 1.36. Since the re-mapping of a purely stochastic signal without any deterministic structure results in a fractal dimension d F = 2, the slope measure 1.36 is an indication that the group signal contains a deterministic structure that is caused by sound radiation from a target. The target is thus detected and the bearing is given by the swivel angle θ of the directional characteristic of the receiving antenna 10 with which the group signal has been received. The value of the fractal dimension d F is present at the output of the function block 14 and can be used to trigger a display for the target detection in a display unit 15.
Um die Falschalarmrate für die Zieldetektion beeinflussen zu können, ist das Ausgangssignal des Funktionsblocks 14, also der Wert der fraktalen Dimension dF, einem Komparator 16 zugeführt, der seinerseits an einem Einsteller 17 für die Falschalarmrate angeschlossen ist. Im Einsteller 17 wird der maximal zugelassene Wert der fraktalen Dimension d^ax vorgegeben, der zwischen 0 und 2 gewählt werden kann. Der Wert "0" der fraktalen Dimension ergibt sich aus der Rückabbildung eines rein harmonischen Gruppensignals, z.B. einer Konsinus- oder Sinusschwingung, während der Wert "2" das Strukturmaß der Abbildung eines rein chaotischen Signals ist. Die Strukturanalyse ergibt also nur dann einen Hinweis auf ein evtl. vorhandenes Ziel, wenn der Wert der fraktalen Dimension 0< d^ax < 2 ist. Um die Falschalarmrate zu drücken, wird beispielsweise d^max mit 1,5 gewählt. Im Komparator 16 wird nunmehr der vorgegebene Maximalwert der fraktalen Dimension dm&x mit dem im Funktionsblock 14 berechneten Wert der fraktalen Dimension dF verglichen. Ist letzterer kleiner als der maximal vorgegebene Wert d^a erzeugt der Komparator 16 ein Ausgangssignal, das in der Anzeigeeinheit 15 die Anzeige für ein detektiertes Ziel auslöst. Gleichzeitig kann in der Anzeigeeinheit 15 der Richtungswinkel θ dargestellt werden, der von dem Richtungsbildner 12 abgenommen und der Anzeigeeinheit 15 zugeführt ist. Hierzu wird von dem Ausgangssignal des Komparators 16 ein Tor 18 geöffnet, an dem der jeweils vom Richtungsbildner 12 momentan eingestellte Schwenkwinkel θ anliegt, unter dem das jeweilige Gruppensignal im Richtungsbildner 12 gebildet wird. In order to be able to influence the false alarm rate for the target detection, the output signal of the function block 14, that is to say the value of the fractal dimension d F , is fed to a comparator 16, which in turn is connected to an adjuster 17 for the false alarm rate. The maximum permissible value of the fractal dimension d ^ ax , which can be chosen between 0 and 2, is specified in the adjuster 17. The value "0" of the fractal dimension results from the re-mapping of a purely harmonic group signal, for example a consine or sine wave, while the value "2" is the structural measure of the mapping of a purely chaotic signal. The structural analysis therefore only gives an indication of a possibly existing target if the value of the fractal dimension is 0 <d ^ ax <2. To press the false alarm rate, select d ^ max with 1.5, for example. The predetermined maximum value of the fractal dimension d m & x is now compared in the comparator 16 with the value of the fractal dimension d F calculated in the function block 14. The latter is smaller as the maximum predetermined value d ^ a, the comparator 16 generates an output signal which triggers the display for a detected target in the display unit 15. At the same time, the directional angle θ can be shown in the display unit 15, which angle has been removed by the directional generator 12 and fed to the display unit 15. For this purpose, a gate 18 is opened by the output signal of the comparator 16, at which the swivel angle θ currently set by the direction generator 12 is applied, at which the respective group signal is formed in the direction generator 12.

Claims

A T L A S E L E K T R O N I K G m b H BremenPATENTANSPRÜCHE ATLASELEKTRONIKG mb H BremenPATENT CLAIMS
1. Verfahren zur Detektion von Zielen, die Wellen, insbesondere Schallwellen, in ein umgebendes Übertragungsmedium abstrahlen, aus Empfangssignalen eines zielfernen Empfängers, dadurch gekennzeichnet, dass die Empfangssignale einer chaostheoretischen Strukturanalyse unterzogen werden und dass bei Auffinden einer zumindest deterministisch-chaotischen Struktur ein Ziel detektiert und die Zieldetektion durch Bewertung der Struktur geprüft wird.1. A method for the detection of targets which emit waves, in particular sound waves, into a surrounding transmission medium, from received signals from a receiver remote from the target, characterized in that the received signals are subjected to a chaos-theoretical structural analysis and that when an at least deterministic-chaotic structure is found, a target is detected and the target detection is checked by evaluating the structure.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass zur Strukturanalyse eine Datenreduktion des zeitlichen Verlaufs des Empfangssignals durchgeführt wird.2. The method according to claim 1, characterized in that a data reduction of the temporal course of the received signal is carried out for the structural analysis.
3. Verfahren nach Anspruch 2, dadurch gekennzeichnet, dass zur Datenreduktion eine Abbildung des Empfangssignals in einen mehrdimensionalen Phasenraum vorgenommen und dass die Struktur der Abbildung bewertet wird.3. The method according to claim 2, characterized in that, for data reduction, the reception signal is mapped into a multidimensional phase space and the structure of the mapping is evaluated.
4. Verfahren nach Anspruch 3, dadurch gekennzeichnet, dass die Abbildung in einen zweidimensionalen Phasenraum durch eine Rückabbildung (Return-Map) vorgenommen wird, indem jeweils ein aus dem zeitlichen Verlauf des Empfangssignals entnommener Wert einer ausgewählten Eigenschaft des Empfangssignals über den Vorwert aufgetragen wird. 4. The method according to claim 3, characterized in that the mapping into a two-dimensional phase space is carried out by means of a re-mapping (return map), in each case by plotting a value of a selected property of the received signal taken from the time profile of the received signal over the previous value.
5. Verfahren nach Anspruch 4, dadurch gekennzeichnet, dass als ausgewählte Eigenschaft die oberen oder unteren Scheitelpunkte oder der zeitliche Abstand der Scheitelpunkte oder in gleichen Zeitintervallen abgenommene Momentanwerte oder die zeitlichen Abstände der Durchstoßpunkte eines Poincare-Schnitts verwendet werden. """- 5. The method according to claim 4, characterized in that the selected properties are the upper or lower vertices or the temporal spacing of the vertices or instantaneous values taken at equal time intervals or the temporal spacings of the penetration points of a Poincare cut. """-
6. Verfahren nach einem der Ansprüche 3 - 5, dadurch gekennzeichnet, dass zur Bewertung der Struktur der Abbildung ein Strukturmaß bestimmt wird und auf Ziel erkannt wird, wenn der Wert des bestimmten Strukturmaßes innerhalb eines vorgegebenen Bereichs des Strukturmaßes liegt.6. The method according to any one of claims 3-5, characterized in that a structural dimension is determined for evaluating the structure of the image and is recognized on target if the value of the specific structural dimension lies within a predetermined range of the structural dimension.
7. Verfahren nach Anspruch 6, dadurch gekennzeichnet, dass als Strukturmaß eine fraktale Dimension (dF) berechnet wird.7. The method according to claim 6, characterized in that a fractal dimension (d F ) is calculated as the structural dimension.
8. Verfahren nach Anspruch 7, dadurch gekennzeichnet, dass die fraktale Dimension (dF) nach dem Gitterverfahren (GV) oder nach dem Abstandsanalyse-Verfahren (AV) oder nach dem Vergrößerungs-Vermehrungsverfahren (VV) berechnet wird.8. The method according to claim 7, characterized in that the fractal dimension (d F ) is calculated according to the grid method (GV) or according to the distance analysis method (AV) or according to the enlargement-increase method (VV).
9. Verfahren nach Anspruch 7 oder 8, dadurch gekennzeichnet, dass ein für eine gewünschte Falschalarmrate maximal zulässiger Wert der fraktalen Dimension (d^a ) festgelegt und der Bereich des Strukturmaßes von Null bis zu dem maximal zulässigen Wert (dpmax) vorgegeben wird. 9. The method according to claim 7 or 8, characterized in that a maximum permissible value for a desired false alarm rate of the fractal dimension (d ^ a) is specified and the range of the structural dimension from zero to the maximum permissible value (dpmax) is specified.
PCT/EP2004/011190 2003-12-04 2004-10-07 Target detecting method WO2005054892A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE2003156578 DE10356578A1 (en) 2003-12-04 2003-12-04 Method for detecting targets
DE10356578.7 2003-12-04

Publications (1)

Publication Number Publication Date
WO2005054892A1 true WO2005054892A1 (en) 2005-06-16

Family

ID=34638318

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2004/011190 WO2005054892A1 (en) 2003-12-04 2004-10-07 Target detecting method

Country Status (2)

Country Link
DE (1) DE10356578A1 (en)
WO (1) WO2005054892A1 (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5696700A (en) * 1995-06-26 1997-12-09 The United States Of America As Represented By The Secretary Of The Navy System and computer-implemented method for fractal-dimension measurement for target-motion analysis noise discrimination
DE19748312A1 (en) * 1996-10-31 1998-05-07 Meidensha Electric Mfg Co Ltd Method for discrimination of time series data value for analysing vehicle gear vibration
US5781460A (en) * 1996-06-28 1998-07-14 The United States Of America As Represented By The Secretary Of The Navy System and method for chaotic signal identification
US6411566B1 (en) * 2001-07-25 2002-06-25 The United States Of America As Represented By The Secretary Of The Navy System and method for processing an underwater acoustic signal by identifying nonlinearity in the underwater acoustic signal
US20020183960A1 (en) * 2001-05-02 2002-12-05 Chiou Ta-Gang Method and system for estimating subject position based on chaos theory

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7764231B1 (en) * 1996-09-09 2010-07-27 Tracbeam Llc Wireless location using multiple mobile station location techniques
US6249252B1 (en) * 1996-09-09 2001-06-19 Tracbeam Llc Wireless location using multiple location estimators
WO2001043067A2 (en) * 1999-12-10 2001-06-14 Durand Technology Limited Improvements in or relating to applications of fractal and/or chaotic techniques

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5696700A (en) * 1995-06-26 1997-12-09 The United States Of America As Represented By The Secretary Of The Navy System and computer-implemented method for fractal-dimension measurement for target-motion analysis noise discrimination
US5781460A (en) * 1996-06-28 1998-07-14 The United States Of America As Represented By The Secretary Of The Navy System and method for chaotic signal identification
DE19748312A1 (en) * 1996-10-31 1998-05-07 Meidensha Electric Mfg Co Ltd Method for discrimination of time series data value for analysing vehicle gear vibration
US20020183960A1 (en) * 2001-05-02 2002-12-05 Chiou Ta-Gang Method and system for estimating subject position based on chaos theory
US6411566B1 (en) * 2001-07-25 2002-06-25 The United States Of America As Represented By The Secretary Of The Navy System and method for processing an underwater acoustic signal by identifying nonlinearity in the underwater acoustic signal

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
BRADLEY E: "Causes and effects of chaos", COMPUTERS AND GRAPHICS, PERGAMON PRESS LTD. OXFORD, GB, vol. 19, no. 5, September 1995 (1995-09-01), pages 755 - 778, XP004000248, ISSN: 0097-8493 *
YANG SHAOQING ET AL: "The natural measure feature of radial noises of ships", ACTA ACUSTICA INST. ACOUST. ACAD. SINICA CHINA, vol. 26, no. 3, May 2001 (2001-05-01), pages 212 - 216, XP009042041, ISSN: 0371-0025 *
ZHANG XINHUA ET AL: "Researches on chaotic phenomena of noises radiated from ships", SHENGXUE XUEBAO; SHENGXUE XUEBAO/ACTA ACUSTICA 1998 SCI PUBL HOUSE, BEIJING, CHINA, vol. 23, no. 2, 1998, pages 134 - 140, XP009042042 *
ZHANG XINHUA: "Chaotic characteristics analyses of underwater acoustic signals", INT CONF SIGNAL PROCESS PROC; INTERNATIONAL CONFERENCE ON SIGNAL PROCESSING PROCEEDINGS, ICSP 1998 IEEE, PISCATAWAY, NJ, USA, vol. 2, 1998, pages 1451 - 1454, XP009042043 *

Also Published As

Publication number Publication date
DE10356578A1 (en) 2005-07-07

Similar Documents

Publication Publication Date Title
DE10258367A1 (en) Multi-objective method and multi-objective sensor device for the distance and angle localization of target objects in the vicinity
EP3339876B1 (en) Method for operating a radar system for preventing deception by third parties
EP2017641A1 (en) Method of passively determining at least the distance to and the position of a target emitting sound and sonar system.
EP1756983B1 (en) Method for detecting targets
WO2005054892A1 (en) Target detecting method
DE102013200458A1 (en) System for environment sensors
EP0213418B1 (en) Method of and apparatus for the direction finding of targets
DE102021112535B3 (en) SONAR METHOD FOR DETECTING AND/OR DETERMINING THE POSITION AND/OR VELOCITY OF UNDERWATER OBJECTS IN A PREDETERMINED AREA, AND A SONAR ARRANGEMENT AND RECEIVING UNIT
EP4226179A1 (en) Method for detecting a missile equipped with surface elements made of metamaterial or &#34;frequency-selective surface&#34; materials
DE10356577B4 (en) Method for emitting and receiving wave energy
DE3345021C2 (en)
WO2018103786A1 (en) Sonar system and method for underwater communication
DE10332886B3 (en) Phased hydrophone array for active sonar system oscillator connected to direction control signal circuit and correlator circuits and reference signal circuit
DE19906572A1 (en) Arrangement for determining direction of incidence of sound waves occurring for limited periods, e.g. for sonar location, has neural network trained with simulated or measurement data
DE3743078B3 (en) Frequency-modulated CW radar system
DE102013209024A1 (en) Method for detecting objects by adaptive beamforming
EP0355669B1 (en) Underwater position-determining device
DE4341364C2 (en) Method for side identification for a direction finder with trailing antenna
DE202019105592U1 (en) Sensing optoelectronic sensor
WO2023275169A1 (en) Method for evaluating a plurality of received signals
DE60217750T2 (en) Group antenna and beam forming by calculation
DE977802C (en) Arrangement for establishing and locating targets that are equipped with a jammer
DE2007228B2 (en) RADAR ARRANGEMENT FOR ELECTRONIC SCANNING OF AN ANGLE SECTOR USING AN SHF ANTENNA
WO2019170797A1 (en) Radar system and method for measuring horizontally dispersed wind fields in the mesosphere and/or lower thermosphere
DE19539068A1 (en) Acoustic monitoring system

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BW BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE EG ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NA NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): BW GH GM KE LS MW MZ NA SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LU MC NL PL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
122 Ep: pct application non-entry in european phase