scholarly journals A Broadband Beamformer Suitable for UUV to Detect the Tones Radiated from Marine Vessels

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2928 ◽  
Author(s):  
Shilong Ma ◽  
Yilin Wang ◽  
Nan Zou ◽  
Guolong Liang
Keyword(s):  
Low Frequency ◽  
Wide Band ◽  
Main Beam ◽  
Simulation Experiments ◽  
Theoretical Derivation ◽  
Band Noise ◽  
Sonar System ◽  
Multiple Beams ◽  
Wide Band Noise ◽  
Marine Vessels

In this paper, the issue that the underwater unmanned vehicle (UUV) with a sonar array achieves the passive detection of vessel targets by detecting the tones radiated from the targets is considered. The multi-beam low-frequency analysis and recording method is widely applied in a manned sonar system. The sonar operator provides an auxiliary decision to extract the target tones from the multiple beams output. However, the complexity of the multi-dimensional information fusion makes it difficult to apply the multi-beam processing in the unmanned sonar system. Aiming at this problem, we introduce the self-adjusting characteristics of adaptive line enhancer to a time domain broadband beamformer and then propose a self-steering broadband beamformer. The proposed beamformer can adaptively steer the main beam to the direction-of-arrival (DOA) of the tonal target. There is no need to pre-form the multiple beams. The complexity of the UUV-based tone detection is reduced. Theoretical derivation and simulation experiments verify that the main beam of the proposed beamformer can track the DOA of tonal target which is rapidly changing. Meanwhile, the tonal interferences as well as the wide-band noise are well suppressed.

Analysis of Evoked and Ongoing Electrical Activity at the Scalp of Human Subjects

1965 ◽  
Vol 8 (4) ◽  
pp. 371-387 ◽  
Author(s):  
Donald C. Teas
Keyword(s):  
Electrical Activity ◽  
Background Activity ◽  
Human Subjects ◽  
Low Frequency ◽  
Wide Band ◽  
Repeated Testing ◽  
Eyes Closed ◽  
Band Noise ◽  
The Subject ◽  
Wide Band Noise

Electrical activity at two locations on the scalp (Vertex and Vertex-3 cm, midline) for an experimental design suitable to clinical application, was recorded on magnetic tape. Data from 5 subjects with normal hearing, for 3 testing days, were processed. Average evoked responses to bursts of wide-band noise (30 dB and 50 dB SL) for two conditions (“eyes closed” and “reading”) were computed. The ongoing background activity was processed by computing its interval histogram. The percentage of ongoing activity within the frequency range 1.5 cps to 17 cps was extracted, and the magnitude of the N 1 -P 2 component of average responses was measured. These measures at the two electrode sites were analyzed by calculating analyses of variance for each of the four sets of data. Percentage of low-frequency background activity and N 1 -P 2 magnitude were positively related only for Day 1. A strong habituation effect appeared for Day 2 and Day 3. Habituation reduced differences between the two conditions and also differences between the two signal strengths for the average responses. Maximum N 1 -P 2 magnitude should be recorded for a single test with the subject relaxed and with his “eyes closed.” For repeated testing a discrimination between signals should be required to offset the attenuation of responses by habituation.

Discrimination of different temporal envelope structures of diotic and dichotic target signals within diotic wide-band noise

2005 ◽  
pp. 397-403 ◽  
Author(s):  
Steven van de Par ◽  
Armin Kohlrausch ◽  
Jeroen Breebaart ◽  
Martin McKinney
Keyword(s):  
Wide Band ◽  
Temporal Envelope ◽  
Band Noise ◽  
Wide Band Noise

On linear filtering under dependent wide-band noise

Stochastics ◽  
1988 ◽  
Vol 23 (4) ◽  
pp. 413-437 ◽  
Author(s):  
A. E. Bashirov
Keyword(s):  
Wide Band ◽  
Linear Filtering ◽  
Band Noise ◽  
Wide Band Noise

Stochastic Averaging of Strongly Nonlinear Oscillators Under Combined Harmonic and Wide-Band Noise Excitations

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
Y. J. Wu ◽  
W. Q. Zhu
Keyword(s):  
Probability Density ◽  
Wide Band ◽  
Nonlinear Oscillators ◽  
Stochastic Averaging ◽  
Random Excitation ◽  
Stationary Response ◽  
Strongly Nonlinear ◽  
Band Noise ◽  
Wide Band Noise ◽  
Strongly Nonlinear Oscillators

Physical and engineering systems are often subjected to combined harmonic and random excitations. The random excitation is often modeled as Gaussian white noise for mathematical tractability. However, in practice, the random excitation is nonwhite. This paper investigates the stationary response probability density of strongly nonlinear oscillators under combined harmonic and wide-band noise excitations. By using generalized harmonic functions, a new stochastic averaging procedure for estimating stationary response probability density of strongly nonlinear oscillators under combined harmonic and wide-band noise excitations is developed. The damping can be linear and (or) nonlinear and the excitations can be external and (or) parametric. After stochastic averaging, the system state is represented by two-dimensional time-homogeneous diffusive Markov processes. The method of reduced Fokker–Planck–Kolmogorov equation is used to investigate the stationary response of the vibration system. A nonlinearly damped Duffing oscillator is taken as an example to show the application and validity of the method. In the case of primary external resonance, based on the stationary joint probability density of amplitude and phase difference, the stochastic jump of the Duffing oscillator and P-bifurcation as the system parameters change are examined for the first time. The agreement between the analytical results and those from Monte Carlo simulation of original system shows that the proposed procedure works quite well.

Pitch Shifts of Tones in Wide‐Band Noise 912–913

1966 ◽  
Vol 40 (5) ◽  
pp. 1203-1203
Author(s):  
Sylvia J. Steiner ◽  
Arnold M. Small
Keyword(s):  
Wide Band ◽  
Band Noise ◽  
Wide Band Noise
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