An Introduction to EdgeTech Sonar systems

Nick Lawrence

EdgeTech

Codevintec Workshop

9th October 2014

• Industry leader in Underwater Acoustics

• EdgeTech (formerly EG&G Marine Instruments)

– Started in 1966 by Doc Edgerton

• ORE Offshore

– Formed in 1963

• Facilities in Massachusetts and Florida

Introduction to EdgeTech

Common Technologies

Underwater Acoustics

Digital Signal Processing

Who uses Sonars ?

Offshore Oil and Gas industry

Regional surveys, Drill site surveys, Pipeline Inspections

Side Scan SonarsBathymetric systemsSub-Bottom Profilers

USBL Systems

Military

MCMRapid Environmental Assessments

Side Scan SonarsBathymetric systems

AUV mounted systems

Port Authorities & Dredging Industry

Wreck locationPre- and post- dredge surveysAggregate extraction surveys

Side Scan SonarsBathymetric systemsSub-Bottom Profilers

Scientific Community

Habitat MappingGeological Surveys

Side Scan SonarsBathymetric systems

AUV mounted systems

Emergency Services

Search and Recovery Side Scan Sonars

– Sideways looking ; 2 sides

– Wide vertical beam

– Narrow horizontal beam

– Towed body

Introduction to Side Scan Sonar

EdgeTech Side Scan Frequencies

Chirp CentreFrequency

NominalFrequency*

Range

120 kHz 100 kHz 250 to 500m

230 kHz 300 kHz 150 to 300m

410 kHz 400 kHz 130 to >200m

540 kHz 600 kHz 100 to 150m

850 kHz 900 kHz 50 to 75m

1600 kHz 1600 kHz 20 to 35m

You will sometimes see the ‘nominal’ frequency quotedin specifications and marketing material.

The selection of the best side scan sonar frequency for any

application is a compromise between range and

resolution. Lower frequency systems provide longer range (allowing a larger area to be covered in each pass), whilst

higher frequency systems provide a higher definition image

4125: Shallow water side scan

Applications : Dams and Embankments

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Applications : Dams and Embankments

An excavator moves a 5 to 8 tonarmour rock into position on March27, the first day of breakwaterrepairs on the Sakonnet PointBreakwater, damaged by hurricanesIrene in August of 2011, and Sandyin October of 2012.

EastBay Newpapers

Applications : Harbour Floor survey

400 kHz Data

Data out to 150m

Applications : Structure Monitoring

Cooling water intakes

Side scan sonar in disaster response

• Side scan sonar in Disaster Response

Wreck location

Wreck Monitoring

Body location

The wreckage of Air France Flight 447 has been found by AUV some 3,900 metres, or nearly 2.5 miles below the surface of the Atlantic Ocean. A search team led by the Woods Hole Oceanographic Institution (WHOI, USA) located the downed plane off Brazil’s northeastern coast.

…They were equipped with Edgetech 120kHz side-scan sonar.

Applications : Air France AF447

PRESS RELEASE from

Woods Hole

Oceanographic Institution

(WHOI, USA)

Applications : Wreck Location

Applications : Wreck Location

Applications : Wreck monitoring

Wreck of the Yankee

1600 kHz data

from a 4125

600/1600 System.

Applications : Wreckage Location

Applications : Body Location

Towed Sub-Bottom Profiler Systems

3100-P

Portable system

for smaller boats

with a choice of

two different

towfish:

216 2 – 16 kHz

424 4 – 24 kHz

3200-XS

Rack mount

system with a

choice of three

different towfish:

512 500 Hz – 12 KHz

216 2 – 16 kHz

424 4 – 24 kHz

Sub-Bottom Profiler Towfish

SB-0512i SB-216S SB-424

Frequency Range 500 Hz – 12 kHz 2 – 16 kHz 4 – 24 kHz

Pulse Type Frequency Modulated

Vertical Resolution (depends on Pulse selected)

8 – 20 cm 6 – 10 cm 4 – 8 cm

Penetration (typical)In coarse calcareous sandIn clay

20 m200 m

6 m80 m

2 m 40 m

Beam Width(depends on centre frequency)

16° - 32° 17° - 24° 16° - 23°

Size (cms) 160 x 124 x 47 105 x 67 x 40 77 x 50 x 34

Weight 190 kg 76 kg 45 kg

Cable requirements 3 shielded twisted pairs (5 conductors used)

Maximum Operating Depth 300 m

Tow Speed 3 – 4 knots optimal, 7 knots max. safe operation

Applications : Geological Survey

Analysis of the Four Brothers Slump,

Lake ChamplainGhosh, Supriti J., 2012.

Unpublished Senior Thesis, Middlebury College, Middlebury,

VT

Applications : Shallow Gas detection

Shallow Gas “masks”

Acoustic data

Bathymetry Applications

• Bathymetric measurements

Enhanced data for Wreck location and Wreck Monitoring

Routine Dredging Monitoring

Pre- and post- crisis checks to determine the extent of changes caused and any impact on navigable channels

Applications : Swath Bathymetry

Sunken overturned

barges

Vertical surfaces

properly imaged

Bathymetry and Side Scan Data

• Co-registered SS with Bathymetry

• Longer Arrays for Higher Resolution Imagery

• 1 to 3cm Range Resolution

Dredge Monitoring of a channel in Florida, USA

Sand waves can be seen building up in the dredged channel

Swath Bathymetry : Dredge Monitoring

Markings from Dredge

Cutter

Quay wall

Entrance to side

channel

Swath Bathymetry : Dredge Monitoring

Summary

• Sonar Systems allow you to image what is under the water

• Applications– Side scan sonar for clearance surveys

– Inspection of underwater assets such as pipelines, and embankments

– Side scan sonar in disaster response

– Sub-bottom profiler survey for site suitability

– Sub-bottom profiler inspection of sediment build up behind dams

– Bathymetry and Sub-bottom profiling for Dredging monitoring

– Bathymetric measurements to monitor navigable channels