underwater detection, classification and localisation: improving the capabilities of towed sonar arrays

182 Pages·2011·14.43 MB·English

UNDERWATER DETECTION, CLASSIFICATION AND
LOCALISATION: IMPROVING THE CAPABILITIES OF
TOWED SONAR ARRAYS
ii
UNDERWATER DETECTION, CLASSIFICATION AND
LOCALISATION: IMPROVING THE CAPABILITIES OF
TOWED SONAR ARRAYS
Proefschift
ter verkrijging van de graad van doctor
aan de Technische Universiteit Delft,
op gezag van de Rector Magnificus prof. ir. K.C.A.M. Luyben;
voorzitter van het College voor Promoties,
in het openbaar te verdedigen op woensdag 20 april 2011 om 10.00 uur
door
Mathieu Edouard Guy Didier COLIN
Ing´enieur
Ecole Nationale Sup´erieure des Etudes et Techniques d’Armement, Brest, Frankrijk
geboren te Straatsburg, Frankrijk
Dit proefschrift is goedgekeurd door de promotor:
Prof. dr. D.G. Simons
Copromotor: Dr. ir. G. Blacqui`ere
Samenstelling promotiecommissie
Rector Magnificus, voorzitter
Prof. dr. D.G. Simons, Technische Universiteit Delft, promotor
Dr. ir. G. Blacqui`ere, Technische Universiteit Delft, copromotor
Prof. dr. Y. P´etillot, Heriot-Watt University
Prof. dr. ir. C.P.A. Wapenaar, Technische Universiteit Delft
Prof. dr. R. Curran, Technische Universiteit Delft
Prof. dr. W. A. Mulder, Technische Universiteit Delft
Dr. X. Lurton, French Research Institute for Exploitation of the Sea
Published and distributed by:
Netherlands Organisation for Applied Scientific Research (TNO)
Postbus 96864
2509 JG Den Haag
ISBN-13 978-90-5986-378-1
Copyright 2011 by M.E.G.D. Colin
Allrightsreserved. Nopartofthematerialprotectedbythiscopyrightnoticemaybereproducedor
utilized in any forms or by any means, electronic or mechanical, including photocopying, recording
or by any information storage and retrieval system, without written permission from the author:
M.E.G.D. Colin, TNO, P.O. Box 969864,2509 JG, The Hague, The Netherlands.
Printed in The Netherlands
Elements from the cover art are adapted from The book of Kells, 800, Trinity College, Dublin.
iv
Contents
1 Introduction 1
1.1 The enemy below . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2 Peering through the depths . . . . . . . . . . . . . . . . . . . . . . . 4
1.3 A versatile sensor: the towed hydrophone array . . . . . . . . . . . . 8
1.4 Advanced Signal processing for an advanced sensor . . . . . . . . . . 11
1.4.1 Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.4.2 Localisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.4.3 Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.5 Towed array sonar experimental data . . . . . . . . . . . . . . . . . . 14
1.6 Contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2 Detection with Passive Synthetic Aperture Sonar 17
2.1 Ideal case . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.1.1 Conventional beamformer response . . . . . . . . . . . . . . . 20
2.1.1.1 Response of the ambient noise. . . . . . . . . . . . . 22
2.1.1.2 Response of the interferer. . . . . . . . . . . . . . . . 23
2.1.1.3 Response of the narrowband source. . . . . . . . . . 25
2.1.2 Integrating snapshots . . . . . . . . . . . . . . . . . . . . . . . 26
2.1.2.1 Incoherent integration . . . . . . . . . . . . . . . . . 28
2.1.2.2 Coherent integration : Synthetic aperture . . . . . . 30
2.1.3 Performance analysis . . . . . . . . . . . . . . . . . . . . . . . 35
2.1.3.1 Performance criteria . . . . . . . . . . . . . . . . . . 35
v
2.1.3.2 Performance comparison . . . . . . . . . . . . . . . . 38
2.1.4 Summary and discussion . . . . . . . . . . . . . . . . . . . . . 41
2.2 Realistic case with perturbations . . . . . . . . . . . . . . . . . . . . 42
2.2.1 Description of the perturbations . . . . . . . . . . . . . . . . . 42
2.2.2 Effect of the perturbations . . . . . . . . . . . . . . . . . . . . 44
2.2.3 Compensation of phase mismatch between snapshots . . . . . 49
2.2.3.1 Description of the phase compensation . . . . . . . . 49
2.2.3.2 Limitations of the phase compensation . . . . . . . . 50
2.2.3.3 Inverse beamforming in combination with ETAM . . 51
2.2.4 Experimental results . . . . . . . . . . . . . . . . . . . . . . . 51
2.2.4.1 2001 Experiment . . . . . . . . . . . . . . . . . . . . 51
2.2.4.2 2003 Experiment . . . . . . . . . . . . . . . . . . . . 54
2.3 Summary and Conclusion . . . . . . . . . . . . . . . . . . . . . . . . 54
3 Localisation with Passive Sonar using Model-Based Methods 57
3.1 Considerations on passive ranging . . . . . . . . . . . . . . . . . . . . 58
3.2 Recursive estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
3.2.1 Narrowband signals . . . . . . . . . . . . . . . . . . . . . . . . 66
3.2.1.1 Design of a processor . . . . . . . . . . . . . . . . . . 68
3.2.1.2 Simulation . . . . . . . . . . . . . . . . . . . . . . . 71
3.2.1.3 Measured data . . . . . . . . . . . . . . . . . . . . . 76
3.2.1.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . 79
3.2.2 Broadband signals . . . . . . . . . . . . . . . . . . . . . . . . 80
3.2.2.1 Time delay estimation . . . . . . . . . . . . . . . . . 80
3.2.2.2 Kalman estimator . . . . . . . . . . . . . . . . . . . 85
3.3 Batch methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
3.3.1 Bearings-Only Target Motion Analysis . . . . . . . . . . . . . 87
3.3.2 Time delay based Target Motion Analysis . . . . . . . . . . . 89
3.3.3 Performance analysis and comparison . . . . . . . . . . . . . . 92
3.3.3.1 Precision . . . . . . . . . . . . . . . . . . . . . . . . 92
3.3.3.2 Observability . . . . . . . . . . . . . . . . . . . . . . 94
3.3.4 Performance comparison . . . . . . . . . . . . . . . . . . . . . 95
3.4 Summary and conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 100
vi
4 Classification with Active Sonar using BPSK Waveforms 101
4.1 Doppler sensitive waveforms . . . . . . . . . . . . . . . . . . . . . . . 103
4.1.1 A zoo of pulses . . . . . . . . . . . . . . . . . . . . . . . . . . 104
4.1.1.1 Comb spectrum pulses . . . . . . . . . . . . . . . . . 104
4.1.1.2 Smooth spectrum pulses . . . . . . . . . . . . . . . . 105
4.1.2 BPSK pulse . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
4.1.3 Limitations of the BPSK waveform . . . . . . . . . . . . . . . 107
4.1.3.1 High data volume . . . . . . . . . . . . . . . . . . . . 107
4.1.3.2 Sensitivity to Doppler perturbation . . . . . . . . . . 108
4.2 Experimental results . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
4.2.1 Experiment description . . . . . . . . . . . . . . . . . . . . . . 112
4.2.2 Experimental ambiguity function . . . . . . . . . . . . . . . . 113
4.2.3 Signal processing . . . . . . . . . . . . . . . . . . . . . . . . . 114
4.2.4 Effect of topography on classification performance . . . . . . . 114
4.2.5 Classification results . . . . . . . . . . . . . . . . . . . . . . . 115
4.3 Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . 118
5 Conclusion and perspective 119
5.1 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
5.1.1 Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
5.1.2 Localisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
5.1.3 Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
5.2 Perspective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
A Probability of False Alarm 125
B Phase unwrapping algorithm 129
C Cram`er-Rao Lower Bounds 133
C.1 CRLB for broadband bearing estimation . . . . . . . . . . . . . . . . 134
C.2 CRLB for Bearing-Only Target Motion Analysis . . . . . . . . . . . . 136
C.3 CRLB for Time Delay Target Motion Analysis . . . . . . . . . . . . . 137
List of Symbols and Notations 139
vii
List of Acronyms 146
Bibliography 147
Summary 159
Samenvatting 163
Acknowledgments 167
Curriculum Vitae 171
viii
Chapter 1
Introduction
Figure from a patent for a Piezo-Electric Signalling Apparatus filed by
Paul Langevin in 1923 [1]
2 CHAPTER 1. INTRODUCTION
”Here there be monsters” The fascination of the undersea world: The Leviathan
(Gustave Dor´e)
Despite being more naturally adapted to walking on land, mankind has always
been attracted to travelling on or in water for several purposes: feeding, travelling,
harvesting resources, hiding, or, of course, just out of sheer curiosity. In any case,
the underwater environment is very mysterious and therefore fascinating to us for
various reasons. Most of Earth’s surface is covered by water and holds many riches
of different kinds the quantity of which we can only suspect. It is an environment
with very varied and dynamic flora, fauna and physics that we are only beginning to
grasp. The depths of the sea are remotely accessible and difficult to monitor, which
makes them even more intriguing for us, but also the perfect hiding place for someone
who wishes to keep a secret agenda.
1.1 The enemy below
The fact that one cannot see very far underwater made it attractive for amateurs of
clandestine operations to make use of the underwater concealing properties. The use