passive acoustic monitoring of moving targets by sparse underwater ...

More documents

Recommendations

Info

© 2008 Viktoria Zetterberg Department of Signal Processing School of Engineering Publisher: Blekinge Institute of Technology Printed by Printfabriken, Karlskrona, Sweden 2008 ISBN 978-91-7295-157-0
White White White White Abstract v Surveillance of sound activities in the sea is of great importance for many applications. A common way to monitor the sea is to register sound with the help of a group of closely placed sensors that form a one-dimensional or two-dimensional array. This is a practical and easy way to monitor sound in large and deep waters where sound spreads in nearly straight lines. In shallow waters, propagation patterns are more complex and also more difficult to predict. Baltic Sea shallow waters also involve large archipelagoes, which make monitoring more difficult. New possibilities to synchronize sensors with the aid of the global positioning system (GPS) facilitate the creation of larger sensor systems. By placing sensors at different positions over the entire water volume under observation, a minimization of the effects from complicated sound spreading is allowed. Near field processing can then also be applied since the sound source is registered by means of several sensors in positions close to the target. These large arrays will have three-dimensional capabilities and they will also provide a much higher resolution than traditional systems. In this thesis it is shown that signals registered hundreds of meters away from each other can be used to position moving sound within the sensor area. Measurement results are presented from four experiments in shallow waters 20 meters deep, located in the Baltic Sea. The measurements were performed with different setups, at different locations and during different seasons. The thesis comprises four parts. The first part presents a comparative study of two methods for estimating the time delay between two measurement signals, where the sound consists of noise and dominant tones. Effects from different geometric setups on the position estimate are shown. The result indicates that larger baselines give better positioning capabilities despite a larger uncertainty in the time delay estimation. The second part of this thesis concerns imaging, which means the projection of multiple pairwise correlation results into a two-dimensional plane. Results from a target placed at a distance equal to the length of the sensor baselines are shown. Weights that can be used to give different sensor pairs different importance in the summation image are investigated. In this case, the target was assumed to consist of one sound source. The third part of the thesis also concerns imaging, but presents results from a target placed at a distance smaller than the length of the sensor baselines. In this part, simulation shows that it is possible
Page 1: Passive Acoustic Monitoring of Movi
Page 5: Blekinge Institute of Technology Li
Page 9: White White White White vii Preface
Page 13: White White White White xi Contents
Page 16 and 17: 14 White White White White 2005 MTS
Page 18 and 19: 16 White Introduction White White f
Page 20 and 21: 18 White Introduction White White C
Page 22 and 23: 20 White Introduction White White C
Page 24 and 25: 22 White Introduction White White (
Page 26 and 27: 24 White Introduction White White P
Page 28 and 29: 26 White Introduction White White R
Page 30 and 31: Part I has been published as: Zette
Page 32 and 33: 30 White Part I III. GENERALIZED CR
Page 34 and 35: 32 White Part I Fig. 6 show a momen
Page 36 and 37: 34 White Part I REFERENCES [1] B. X
Page 38 and 39: Part II has been published as: Zett
Page 40 and 41: 38 White Part II GCC function [4] i
Page 42 and 43: 40 White Part II C. Frequency depen
Page 44 and 45: 42 White Part II a pair, thereby en
Page 46 and 47: Part III has been published as: Zet
Page 48 and 49: 46 White Part III xm 1 ( t) s( t)
Page 50 and 51: 48 White Part III VI. RESULTS To il
Page 52 and 53: 50 White Part III ACKNOWLEDGMENT Th
Page 54 and 55: Part IV i submitted as: Zetterberg,
Page 56 and 57:
54 White Part IV capabilities and t
Page 58 and 59:
56 White Part IV However, with the
Page 60 and 61:
58 White Part IV Table 1: Target, e
Page 62 and 63:
60 White Part IV 1B, the engine sou
Page 64 and 65:
62 White Part IV 140 130 Magnitude
Page 66 and 67:
64 White Part IV coordinate system
Page 68 and 69:
66 White Part IV Table 3: Differenc
Page 70 and 71:
68 White Part IV drawn for zero del
Page 72 and 73:
70 White Part IV 60 Bandwidth depen
Page 74 and 75:
72 White Part IV 5.2.2 Results For
Page 76 and 77:
74 White Part IV Figure 15: Setup 1
Page 78 and 79:
76 White Part IV 5.3.2 Results The
Page 80 and 81:
Page 82 and 83:
Page 84 and 85:
Page 86 and 87:
84 White Part IV 4040, Orlando, FL,
Page 90:
ABSTRACT Surveillance of sound acti
show all

passive acoustic monitoring of moving targets by sparse underwater ...

Create successful ePaper yourself

Delete template?

Save as template?