Page 394 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition

Sonar
CHAPTER CONTENTS
15
15.1 Sonar basics...............................................................................................................................388
15.1.1 Why sound? ....................................................................................................... 388 15.1.2 Definitionofsonar..............................................................................................388 15.1.3 Elements required for sonar equipment ................................................................ 389 15.1.4 Frequency and signal attenuation......................................................................... 389 15.1.5 Active versus passive sonar ................................................................................. 390 15.1.6 Transducers.......................................................................................................390 15.1.7 Activesonar.......................................................................................................394 15.1.8 Terminology.......................................................................................................395 15.1.9 Sonarequations.................................................................................................397
15.1.10 Reflectivity and gain setting ................................................................................ 398 15.1.11 Sound backscatter.............................................................................................. 399 15.1.12 Single-versusmultibeam....................................................................................401 15.1.13 Frequency versus image quality ........................................................................... 402
15.2 Sonar types and interpretation.....................................................................................................404
15.2.1 Imagingsonar......................................................................................................404
15.2.2 Profiling sonar...................................................................................................... 404
15.2.3 Side-scanversusmechanically/electricallyscanning................................................406
15.2.4 Single-/dual-/multifrequency versus tunable frequency ............................................ 409
15.2.5 CHIRP technology and acoustic lens systems.......................................................... 410
15.2.5.1 CHIRPsonar..................................................................................................410
15.2.5.2 Acoustic lens sonar ........................................................................................ 413
15.3 Sonar techniques........................................................................................................................416
15.3.1 Using an imaging sonar on an ROV ........................................................................ 416 15.3.2 Technique for locating targets with ROV-mounted scanning sonar ............................. 418 15.3.3 Interpretation of sonar images ............................................................................... 419
15.4 New and emerging technologies ..................................................................................................420
15.4.1 Imagecapture......................................................................................................420 15.4.2 Imagerendering...................................................................................................421
The ROV Manual.
© 2014 Robert D Christ and Robert L Wernli. Published by Elsevier Ltd. All rights reserved.
387
CHAPTER