Optimizing Multibeam Data

Quality Across the Fleet

TIM GATES (Gates Acoustic Services)

VICKI FERRINI (LDEO)

JONATHAN BEAUDOIN (CCOM-UNH)

PAUL JOHNSON (CCOM-UNH)

JOHN HUGHES CLARKE (OMG-UNB)

BackgroundMB workshop at NSF June 2010 in response to fleet-

wide issues with multibeam performance

Goals:Discuss operation of the sonarsIdentify common threads in documented problemsGet advice from domain experts and other MB

users

Outcomes:Identified several specific operational and

technical issues, some poorly understood, impacting multibeam data quality

Identified a strong need to coordinate operational and technical efforts across the fleet

UNOLS FLEET

SCRIPPSMELVILLEROGER REVELLE

WHOIKNORRATLANTIS

UW – THOMAS THOMPSON

UH – KILO MOANA

LDEO – MARCUS LANGSETH

Multibeam Advisory Committee (MAC)

Fleet-wide Approach

Facilitate Communication

Community of Stakeholders

Technical Resources

Technical TeamsShipboard AcceptanceAcoustic NoiseQuality Assurance

Best Practices

Transition into a UNOLS Committee

MAC: Committee Planning

In-person meeting once per year Supplement with Telecon/Web Conferencing

Review Technical Team activities & products

Prioritize ship visits

Address practical implementation of best practices

Discuss concerns/issues from Operators

Ensure MAC is providing necessary resources

Overview of Technical Teams

ANT and SAT: help optimize ship and system performance

QAT: help optimize the way data is acquired

MAC: Acoustic Noise Team

Goal: Perform acoustic noise tests to assess and potentially improve sensor efficiency (coverage) and data quality

Establish baseline noise levels

Help populate an archive of historical data on noise properties of each vessel to aid in monitoring over sensor lifetime

Anticipate 2 ship visits per year

MAC: Shipboard Acceptance Team

Goal: Ensure all hull-mounted multibeam systems are installed, calibrated, and configured properly and consistently

Participate in Sea Acceptance Trials for new and/or poorly understood existing installations

Anticipate 2 ship visits per year

MAC: Quality Assurance Team

Goal: Ensure multibeam sonar systems are operated in a consistent manner that maximizes data accuracy, precision, and scientific utility

Develop and disseminate best practice documentation

Develop and deploy tools and procedures to optimize data quality during acquisition

Technical Teams in Action

Acoustic Noise Testing

It is planned to acquire baseline acoustic signatures from each UNOLS vessel

Signatures will be acquired from test hydrophones and internal sonar noise routines

Results of acoustic testing will determine: Propeller cavitation Hydrodynamic flow noise Machinery contributions Bubble sweepdown impacts

Data will be archived for future comparisons and trending of noise backgrounds

Acoustic Testing

R/V MELVILLE was tested in January

R/V KILO MOANA is scheduled for testing in June

Previous tests (prior to the MAC) have been accomplished on:R/V REVELLER/V KILO MOANAR/V MARCUS LANGSETHR/V ATLANTIS

Benefits of Acoustic Testing

Identify acoustic deficiencies that limit full sonar performance

Provide corrective actions for problem areas

Develop “quiet” machinery line-ups for best performance

Develop operational guidance to mitigate acoustic noise issues

Recent Acoustic Findings

ATLANTIS – has a cavitating gondola

LANGSETH – quieter at 9 knots than 0 to 8 knots due to controllable pitch propellers

KILO MOANA – Above 9 knots data is controlled by diesel engines which limit sonar performance

MELVILLE – anti-roll system limits sonar performance during roll cycles

REVELLE – bubble sweepdown transients limit sonar performance in higher sea states

QAT: R/V Kilo MoanaShip Geometry Verification

Verification of current system geometry by establishing “chain of custody” by reviewing: Ship drawings Blom survey (2005): initial survey of mapping system

offsets Applanix site visit reports (2006 & 2008) IMTEC survey (2012): survey of new EM710 installation

Independently established linear and angular offsets from above documentation and verbal reports of configuration changes

Found and corrected errors in current configuration: Primary GPS location in POS/MV configuration Pitch offset in EM710 configuration

QAT: R/V Kilo MoanaAssessment of Documentation

Found hardcopy and softcopy operators manuals for EM122 and EM710

Found out-dated “cookbooks” for EM1002/EM120 on technician’s wiki

Newer “cookbooks” generated for EM710/EM122 and focused on SISHow to backup all system settingsHow to uninstall SIS and remove the databaseHow to re-install SIS and import system settings to

get system back to last known good configuration

QAT: R/V Kilo MoanaSoftware Deployment: SVP

Editor Graphical display and editing of XBT

data: can interact with data to remove outliers

Implements proposed best-practices: Augment with database salinity profile

(World Ocean Atlas 2009) Embed measured surface sound speed

in upper layer Use database for vertical extension of

cast

Server mode: automatically delivers World Ocean Atlas sound speed profiles to SIS while in transit

Streamlined processing allows for delivery of cast to SIS for immediate application

SIS

QAT: R/V Kilo MoanaSoftware Deployment: BIST

Loggerpython script to log BIST output over network via UDP

Includes vessel position/speed and engine RPMs; reduces requirement to embed “metadata” in filenames, e.g. starboard_engine_200_rpm_5kts_045_heading_BIST.txt

Enables acquisition of rich acoustic noise data sets with minimal effort

Results from acquisition of 294 BIST noise spectrum measurements over 38 minute time span with gradual increases in ship speed. Achieved with one operator repeatedly launching the appropriate BIST test; all data and metadata were logged automatically. Plot generated with Matlab.

We value your input!

You can benefit: Reports and tools will be available publicly online

You can contribute also:Best practice documentationIdeasMultibeam Horror/Success stories

http://mac.unols.org/