We report here the observation result of joint observation of long period tremor signals with broadband seismome-ter,tiltmeter and gravimeter at the HUST(Huazhong University of Science and Technology)station.The obser...We report here the observation result of joint observation of long period tremor signals with broadband seismome-ter,tiltmeter and gravimeter at the HUST(Huazhong University of Science and Technology)station.The observed data were compared and analyzed.Since 2005,the several tens of abnormal tremor signals which are weak,com-plex and duration of 2 to 3 days have been synchronously recorded by the different instruments.The tremor signals have the periodic domain in the range of 3 to 5 minutes,20 to 30 minutes and even more than 1 hour.The observa-tion shows such tremors are a physical existence.The analysis indicates that a part of the tremors caused by the typhoon from the western Pacific Ocean.These tremors have a close relationship with wind velocity of typhoon and distance between the typhoon center and the station.Except these,the cause of others is still unclear.展开更多
The basic principles of target detection by forward acoustic scattering are presented.A direct blast suppression approach based on adaptive filtering(DBS-AF) is proposed to suppress the direct blast.The DBS-AF techniq...The basic principles of target detection by forward acoustic scattering are presented.A direct blast suppression approach based on adaptive filtering(DBS-AF) is proposed to suppress the direct blast.The DBS-AF technique is extended to the linear frequency modulation(LFM) signal,where the envelope of the signal is regarded as a 'general waveform' and imported into the adaptive filter.Application of the DBS-AF method to the data collected from a lake trial yields an output detection curve,in which the direct blast is mapped to the background while the acoustic field aberration is represented by the peak value fluctuation.The inhibitory effect in single hydrophone is approximately- 5 dB,and is then enhanced by exploiting the mean value removal approach as a preprocessing technique.The direct blast is further suppressed to a level of-10 dB by making full use of multichannel receptions.The main factors affecting the algorithm performance are as follows:the fluctuation degree of the receptions during the weighting vector training period and the power ratio of the forward scattered wave to the direct blast when the target is present.展开更多
A theoretical relationship between the wavelet transform and the fast fourier transformation(FFT) methods in broadband wireless signal is proposed for solving the direction of arrivals(DOAs) estimation problem. This l...A theoretical relationship between the wavelet transform and the fast fourier transformation(FFT) methods in broadband wireless signal is proposed for solving the direction of arrivals(DOAs) estimation problem. This leads naturally to the derivation of minimum variance distortionless response(MVDR) algorithm, which combines the benefits of subspace methods with those of wavelet, and spatially smoothed versions are utilized which exhibits good performance against correlated signals. We test the method's performance by simulating and comparing the performance of proposed algorithm, FFT MVDR and MVDR with correlated signals, and an improved performance is obtained.展开更多
The 2011 Tohoku-oki earthquake,occurred on 11 March,2011,is a great earthquake with a seismic magnitude Mw9. 1,before which an Mw7. 5 earthquake occurred. Focusing on this great earthquake event,we applied Hilbert-Hua...The 2011 Tohoku-oki earthquake,occurred on 11 March,2011,is a great earthquake with a seismic magnitude Mw9. 1,before which an Mw7. 5 earthquake occurred. Focusing on this great earthquake event,we applied Hilbert-Huang transform（ HHT） analysis method to the one-second interval records at seven superconducting gravimeter（ SG） stations and seven broadband seismic（ BS） stations to carry out spectrum analysis and compute the energy-frequency-time distribution. Tidal effects are removed from SG data by T-soft software before the data series are transformed by HHT method. Based on HHT spectra and the marginal spectra from the records at selected seven SG stations and seven BS stations we found anomalous signals in terms of energy. The dominant frequencies of the anomalous signals are respectively about 0. 13 Hz in SG records and 0. 2 Hz in seismic data,and the anomalous signals occurred one week or two to three days prior to the event. Taking into account that in this period no typhoon event occurred,we may conclude that these anomalous signals might be related to the great earthquake event.展开更多
在被动声纳对宽带接收信号的处理过程中,常规波束形成器存在波束较宽,方向分辨率低,输出信噪比低等问题,进而导致信号源的方向估计不准确。论文针对常规波束形成器的上述问题,提出了反卷积峰值能量检测算法(Deconvolved Peak Energy Det...在被动声纳对宽带接收信号的处理过程中,常规波束形成器存在波束较宽,方向分辨率低,输出信噪比低等问题,进而导致信号源的方向估计不准确。论文针对常规波束形成器的上述问题,提出了反卷积峰值能量检测算法(Deconvolved Peak Energy Detection Method,DPED)。该算法通过对常规波束形成器的输出进行反卷积计算,提高了输出信噪比,优化了常规波束形成器的空间谱显示。文章讨论了反卷积波束形成的基本方法,给出了反卷积峰值能量检测算法的基本实现流程。通过仿真验证了该算法的有效性。展开更多
针对宽带雷达检测门限值设置难度大、系统复杂度高、实时性差等问题,提出了一种UWB-SOSCA(Ultra-Wide Band-Smallest of Ordered Statistics and Cell Average)检测算法。该算法主要包括多相滤波、SOSCA恒虚警检测和二元积累。其中,多...针对宽带雷达检测门限值设置难度大、系统复杂度高、实时性差等问题,提出了一种UWB-SOSCA(Ultra-Wide Band-Smallest of Ordered Statistics and Cell Average)检测算法。该算法主要包括多相滤波、SOSCA恒虚警检测和二元积累。其中,多相滤波将宽带信号划分为多个子信道,降低通道速率;SOSCA恒虚警检测分别对各子信道进行自适应门限调整,提高各子信道检测概率;二元积累对各子信道的检测结果进行时域联合,优化宽带时域连续检测性能。实验结果表明,在信噪比等于7.33 dB,虚警概率为10~(-5)时,SOSCA恒虚警检测算法与传统恒虚警算法相比,检测概率可提升14%;当多相滤波输入信噪比为-5 dB时,UWB-SOSCA算法的宽带线性调频信号脉冲宽度测量偏差优于6.5 ns。该算法具有大监视带宽、大动态范围和高检测概率,可广泛应用于侦察接收机的雷达侦测工作。展开更多
A frequency invariant response algorithm is proposed for getting over the signal distortion in high frequency when the beamformer receives the broadband signals. In this method, the weight vector of the reference beam...A frequency invariant response algorithm is proposed for getting over the signal distortion in high frequency when the beamformer receives the broadband signals. In this method, the weight vector of the reference beam pattern is designed firstly, then the weight vectors when the beam response in the frequency sub-bands approaching the reference response mostly are computed by optimized method or adaptive method. By this method, the beam pattern in each sub-band can be almost kept invariable. As a result, the receiving chirp signal can be improved. Owing to the adoption of the adaptive method to approach the optimized vectors, it has no restricting of the array format and the element directivity, and the method can be used widely.展开更多
随着军用无人机等航电系统不断朝着小型化、智能化、综合化的方向发展,如何有效满足装备的低SWaP(Size,Weight and Power)要求成为一大难题。介绍了某型宽带综合化数字预处理模块的研制,利用“裸芯片+高密度基板”系统级封装(SiP)的方...随着军用无人机等航电系统不断朝着小型化、智能化、综合化的方向发展,如何有效满足装备的低SWaP(Size,Weight and Power)要求成为一大难题。介绍了某型宽带综合化数字预处理模块的研制,利用“裸芯片+高密度基板”系统级封装(SiP)的方式对信号处理平台(DSP、FPGA、SerDes和DDR芯片)进行集成,替代目前业界普遍采用的“封装芯片+印制板+平面集成”的传统方式,实现宽带综合化数字信号处理模块的高密度集成。在主要性能指标(可编程逻辑资源、定点处理能力、浮点处理能力、数据传输速率)不变的情况下,使得信号处理模块的面积降低为45 mm×45 mm,重量降低到103 g。展开更多
文摘We report here the observation result of joint observation of long period tremor signals with broadband seismome-ter,tiltmeter and gravimeter at the HUST(Huazhong University of Science and Technology)station.The observed data were compared and analyzed.Since 2005,the several tens of abnormal tremor signals which are weak,com-plex and duration of 2 to 3 days have been synchronously recorded by the different instruments.The tremor signals have the periodic domain in the range of 3 to 5 minutes,20 to 30 minutes and even more than 1 hour.The observa-tion shows such tremors are a physical existence.The analysis indicates that a part of the tremors caused by the typhoon from the western Pacific Ocean.These tremors have a close relationship with wind velocity of typhoon and distance between the typhoon center and the station.Except these,the cause of others is still unclear.
基金supported by the National Natural Science Foundation of China(11174235,61571366)
文摘The basic principles of target detection by forward acoustic scattering are presented.A direct blast suppression approach based on adaptive filtering(DBS-AF) is proposed to suppress the direct blast.The DBS-AF technique is extended to the linear frequency modulation(LFM) signal,where the envelope of the signal is regarded as a 'general waveform' and imported into the adaptive filter.Application of the DBS-AF method to the data collected from a lake trial yields an output detection curve,in which the direct blast is mapped to the background while the acoustic field aberration is represented by the peak value fluctuation.The inhibitory effect in single hydrophone is approximately- 5 dB,and is then enhanced by exploiting the mean value removal approach as a preprocessing technique.The direct blast is further suppressed to a level of-10 dB by making full use of multichannel receptions.The main factors affecting the algorithm performance are as follows:the fluctuation degree of the receptions during the weighting vector training period and the power ratio of the forward scattered wave to the direct blast when the target is present.
基金supported by the Chinese Natural Science Foundation 61401075Central University Business Fee ZYGX2015J106
文摘A theoretical relationship between the wavelet transform and the fast fourier transformation(FFT) methods in broadband wireless signal is proposed for solving the direction of arrivals(DOAs) estimation problem. This leads naturally to the derivation of minimum variance distortionless response(MVDR) algorithm, which combines the benefits of subspace methods with those of wavelet, and spatially smoothed versions are utilized which exhibits good performance against correlated signals. We test the method's performance by simulating and comparing the performance of proposed algorithm, FFT MVDR and MVDR with correlated signals, and an improved performance is obtained.
基金supported by National 973 Project China(2013CB733305)NSFC(41174011,41128003,41210006,41021061,40974015)
文摘The 2011 Tohoku-oki earthquake,occurred on 11 March,2011,is a great earthquake with a seismic magnitude Mw9. 1,before which an Mw7. 5 earthquake occurred. Focusing on this great earthquake event,we applied Hilbert-Huang transform（ HHT） analysis method to the one-second interval records at seven superconducting gravimeter（ SG） stations and seven broadband seismic（ BS） stations to carry out spectrum analysis and compute the energy-frequency-time distribution. Tidal effects are removed from SG data by T-soft software before the data series are transformed by HHT method. Based on HHT spectra and the marginal spectra from the records at selected seven SG stations and seven BS stations we found anomalous signals in terms of energy. The dominant frequencies of the anomalous signals are respectively about 0. 13 Hz in SG records and 0. 2 Hz in seismic data,and the anomalous signals occurred one week or two to three days prior to the event. Taking into account that in this period no typhoon event occurred,we may conclude that these anomalous signals might be related to the great earthquake event.
文摘在被动声纳对宽带接收信号的处理过程中,常规波束形成器存在波束较宽,方向分辨率低,输出信噪比低等问题,进而导致信号源的方向估计不准确。论文针对常规波束形成器的上述问题,提出了反卷积峰值能量检测算法(Deconvolved Peak Energy Detection Method,DPED)。该算法通过对常规波束形成器的输出进行反卷积计算,提高了输出信噪比,优化了常规波束形成器的空间谱显示。文章讨论了反卷积波束形成的基本方法,给出了反卷积峰值能量检测算法的基本实现流程。通过仿真验证了该算法的有效性。
基金Supported by the 863 Foundation under Grant No.2002AA602230.
文摘A frequency invariant response algorithm is proposed for getting over the signal distortion in high frequency when the beamformer receives the broadband signals. In this method, the weight vector of the reference beam pattern is designed firstly, then the weight vectors when the beam response in the frequency sub-bands approaching the reference response mostly are computed by optimized method or adaptive method. By this method, the beam pattern in each sub-band can be almost kept invariable. As a result, the receiving chirp signal can be improved. Owing to the adoption of the adaptive method to approach the optimized vectors, it has no restricting of the array format and the element directivity, and the method can be used widely.
