The disguised covert detection method that imitates whale calls has received great attention in recent years because it can solve the traditional problem of the trade-off between long-range detection and covert detect...The disguised covert detection method that imitates whale calls has received great attention in recent years because it can solve the traditional problem of the trade-off between long-range detection and covert detection.However,under strong reverberation conditions,traditional echo signal processing methods based on matched filtering will be greatly disturbed.Based on this,a disguised sonar signal waveform design is proposed based on imitating whale calls and computationally efficient anti-reverberation echo signal processing method.Firstly,this article proposed a disguised sonar signal waveform design method based on imitating whale calls.This method uses linear frequency modulation(LFM)signals to replace LFM-like segments in real whale calls,and extracts the envelope of the real whale call’s LFM-like segment to modify the LFM signal.Secondly,this article proposed an echo signal processing method of fractional Fourier transform(FrFT)based on target echo locating of synchronization signals.This method uses the synchronization signal to locate the target echo,and determines the step-size interval of the FrFT based on the information carried by the synchronization signal.Compared with the traditional FrFT,this method effectively reduces the amount of calculation and also improves the anti-reverberation ability.Finally,the excellent performance of the proposed method is verified by simulation results.展开更多
For the constant false alarm rate(CFAR)detection problem of active sonar in complex environment and propagation channel,an automatic CFAR detection method of active sonar based on hierarchical filters was proposed.Fir...For the constant false alarm rate(CFAR)detection problem of active sonar in complex environment and propagation channel,an automatic CFAR detection method of active sonar based on hierarchical filters was proposed.Firstly,based on the spatial response characteristics of the array and the morphological characteristics of the target echo,a spatio-temporal filter was designed to remove the background noise and reverberation signal.Then,a linear and nonlinear combined spatial filter were designed to extract the energy accumulation area of the active sonar sonogram.Finally,the multi-dimensional features such as the spatial azimuth distribution of the target echo,the shape matching and the signal-to-noise ratio between the accumulation point and the adjacent background were calculated and fused to realize the target detection.Numerical simulation and sea test data show that,the probability of automatically detecting targets by this algorithm is larger than 85%in three typical cases,and this algorithm can detect targets when the background noise fluctuates greatly,showing that the algorithm is more robust.展开更多
Resolution enhancement of active sonar can suppress the reverberation.While it also makes the envelope data distribution diverge from Rayleigh distribution to K-distribution.The stronger scattering speckles,the heavie...Resolution enhancement of active sonar can suppress the reverberation.While it also makes the envelope data distribution diverge from Rayleigh distribution to K-distribution.The stronger scattering speckles,the heavier of the K-distribution tails.The envelope amplitudes of these strong scattering speckles are usually very big.As the interfering target,the strong reverberation decreases the performances of the background power level estimation and the target detection.The fuzzy statistical normalization processing(FSNP) is introduced to suppress the strong reverberation firstly in this paper.Then how the strong reverberation and the FSNP affect the distribution of K-distributed sonar data is studied.The influence on the constant false alarm rate(CFAR) detection performance caused by the strong reverberation and the FSNP is also simulated and analyzed.Performance comparisons between the CFAR detector based on FSNP and the conventional CFAR detectors are carried out.The simulation results show that the strong reverberation can make the shape parameter of the interfering K-distributed data become smaller than that of the original K-distributed data.While the FSNP can suppress the strong reverberation,increase the shape parameter value,and improve the performance of the shape parameter estimator and the CFAR detector.展开更多
A tracking filter algorithm based on the maneuvering detection delay is presented in order to solve the fuzzy problem of target maneuver decision introduced by the measure？ment errors of active sonar. When the maneuv...A tracking filter algorithm based on the maneuvering detection delay is presented in order to solve the fuzzy problem of target maneuver decision introduced by the measure？ment errors of active sonar. When the maneuvering detection is unclear, two target moving hypotheses, the uniform and the maneuver, derived from the method of multiple hypothesis tracking, are generated to delay the final decision time. Then the hypothesis test statistics is constructed by using the residual sequence. The active sonar？s tracking ability of unknown prior information targets is improved due to the modified sequential probability ratio test and the integration of the advantages of strong tracking filter and the Kalman filter. Simulation results show that the algorithm is able to not only track the uniform targets accurately, but also track the maneuvering targets steadily. The effectiveness of the algorithm for real underwater acoustic targets is further verified by the sea trial data processing results.展开更多
While using the bottom bounce mode to detect deep-sea shadow zone,the signal-to-noise ratio decreases due to the influence of the seabed reflection loss on the signal,which poses great difficulties for target detectio...While using the bottom bounce mode to detect deep-sea shadow zone,the signal-to-noise ratio decreases due to the influence of the seabed reflection loss on the signal,which poses great difficulties for target detection.Therefore,this article establishes a signal model based on the propagation law of sound in deep-sea shadow zone and analyzes the multipath structural characteristics of signals in shadow channels.Based on the principle of generalized likelihood ratio test,the detector suitable for target detection in shadow zone is designed according to the single beam multipath structural characteristics and spatial beam splitting characteristics.The simulation results and real data processing results both indicate that the proposed detector has significantly improved detection performance compared to traditional matched filter detectors by extracting and utilizing the multipath structural features of the echo of the shadow zone.展开更多
基金National Natural Science Foundations of China under Grant(Nos.61971307,61905175,51775377)National Key Research and Development Plan Project(No.2020YFB2010800)+5 种基金Fok Ying Tung Education Foundation(No.171055)China Postdoctoral Science Foundation(No.2020M680878)Guangdong Province Key Research and Development Plan Project(No.2020B0404030001)Tianjin Science and Technology Plan Project(No.20YDTPJC01660)Foreign Affairs Committee of China Aviation Development Sichuan Gas Turbine Research Institute(Nos.GJCZ-2020-0040,GJCZ-2020-0041)Science and Technology on Underwater Information and Control Laboratory under Grant(No.6142218081811)。
文摘The disguised covert detection method that imitates whale calls has received great attention in recent years because it can solve the traditional problem of the trade-off between long-range detection and covert detection.However,under strong reverberation conditions,traditional echo signal processing methods based on matched filtering will be greatly disturbed.Based on this,a disguised sonar signal waveform design is proposed based on imitating whale calls and computationally efficient anti-reverberation echo signal processing method.Firstly,this article proposed a disguised sonar signal waveform design method based on imitating whale calls.This method uses linear frequency modulation(LFM)signals to replace LFM-like segments in real whale calls,and extracts the envelope of the real whale call’s LFM-like segment to modify the LFM signal.Secondly,this article proposed an echo signal processing method of fractional Fourier transform(FrFT)based on target echo locating of synchronization signals.This method uses the synchronization signal to locate the target echo,and determines the step-size interval of the FrFT based on the information carried by the synchronization signal.Compared with the traditional FrFT,this method effectively reduces the amount of calculation and also improves the anti-reverberation ability.Finally,the excellent performance of the proposed method is verified by simulation results.
基金supported by the China State Shipbuilding Corporation Equipment Pre-Research Joint Fund(6141B03090103).
文摘For the constant false alarm rate(CFAR)detection problem of active sonar in complex environment and propagation channel,an automatic CFAR detection method of active sonar based on hierarchical filters was proposed.Firstly,based on the spatial response characteristics of the array and the morphological characteristics of the target echo,a spatio-temporal filter was designed to remove the background noise and reverberation signal.Then,a linear and nonlinear combined spatial filter were designed to extract the energy accumulation area of the active sonar sonogram.Finally,the multi-dimensional features such as the spatial azimuth distribution of the target echo,the shape matching and the signal-to-noise ratio between the accumulation point and the adjacent background were calculated and fused to realize the target detection.Numerical simulation and sea test data show that,the probability of automatically detecting targets by this algorithm is larger than 85%in three typical cases,and this algorithm can detect targets when the background noise fluctuates greatly,showing that the algorithm is more robust.
基金supported by the National Natural Science Foundation of China(61431020,61471352,61671443)
文摘Resolution enhancement of active sonar can suppress the reverberation.While it also makes the envelope data distribution diverge from Rayleigh distribution to K-distribution.The stronger scattering speckles,the heavier of the K-distribution tails.The envelope amplitudes of these strong scattering speckles are usually very big.As the interfering target,the strong reverberation decreases the performances of the background power level estimation and the target detection.The fuzzy statistical normalization processing(FSNP) is introduced to suppress the strong reverberation firstly in this paper.Then how the strong reverberation and the FSNP affect the distribution of K-distributed sonar data is studied.The influence on the constant false alarm rate(CFAR) detection performance caused by the strong reverberation and the FSNP is also simulated and analyzed.Performance comparisons between the CFAR detector based on FSNP and the conventional CFAR detectors are carried out.The simulation results show that the strong reverberation can make the shape parameter of the interfering K-distributed data become smaller than that of the original K-distributed data.While the FSNP can suppress the strong reverberation,increase the shape parameter value,and improve the performance of the shape parameter estimator and the CFAR detector.
文摘A tracking filter algorithm based on the maneuvering detection delay is presented in order to solve the fuzzy problem of target maneuver decision introduced by the measure？ment errors of active sonar. When the maneuvering detection is unclear, two target moving hypotheses, the uniform and the maneuver, derived from the method of multiple hypothesis tracking, are generated to delay the final decision time. Then the hypothesis test statistics is constructed by using the residual sequence. The active sonar？s tracking ability of unknown prior information targets is improved due to the modified sequential probability ratio test and the integration of the advantages of strong tracking filter and the Kalman filter. Simulation results show that the algorithm is able to not only track the uniform targets accurately, but also track the maneuvering targets steadily. The effectiveness of the algorithm for real underwater acoustic targets is further verified by the sea trial data processing results.
基金supported by the National Natural Science Foundation of China(E211130101).
文摘While using the bottom bounce mode to detect deep-sea shadow zone,the signal-to-noise ratio decreases due to the influence of the seabed reflection loss on the signal,which poses great difficulties for target detection.Therefore,this article establishes a signal model based on the propagation law of sound in deep-sea shadow zone and analyzes the multipath structural characteristics of signals in shadow channels.Based on the principle of generalized likelihood ratio test,the detector suitable for target detection in shadow zone is designed according to the single beam multipath structural characteristics and spatial beam splitting characteristics.The simulation results and real data processing results both indicate that the proposed detector has significantly improved detection performance compared to traditional matched filter detectors by extracting and utilizing the multipath structural features of the echo of the shadow zone.
