Tritech SeaKing Sidecan, SeaKing SK150 Sidescan, ROV Sidescan, Towfish, SeaKing Towfish Sidecan Operator's Manual

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SeaKing Sidecan Sonars

Towfish, SK150 and ROV Sidescan

0374-SOM-00013, Issue: 01

SeaKing Sidecan Sonars SeaKing Sidecan Sonars

0374-SOM-00013, Issue: 01

The copyright in this document is the property of Tritech International Ltd. The document is supplied by Tritech International Ltd on the understanding that it may not be copied, used, or disclosed to others except as authorised in writing by Tritech International Ltd.

Tritech International Ltd reserves the right to change, modify and update designs and specifications as part of their ongoing product development programme.

All product names are trademarks of their respective companies.

SeaKing Sidecan Sonars

0374-SOM-00013, Issue: 01

Table of Contents

Help & Support ........................................................................................................ 5

Warning Symbols ..................................................................................................... 6

1. Introduction .......................................................................................................... 7

I. Specification ......................................................................................................... 8

2. SeaKing ROV Sidescan ............................................................................... 9

2.1. Dimensions of Electronics Pod ........................................................ 9

2.2. Dimensions of Transducers .............................................................. 9

2.3. Physical Properties ............................................................................ 9

2.4. Electrical, Communication & Software .......................................... 10

2.5. Acoustic Properties ......................................................................... 10

3. SeaKing Towfish ....................................................................................... 11

3.1. Dimensions ..................................................................................... 11

3.2. Physical Properties .......................................................................... 11

3.3. Electrical, Communication & Software .......................................... 11

3.4. Acoustic Properties ......................................................................... 12

4. SeaKing Towfish SK150 ........................................................................... 13

4.1. Dimensions ..................................................................................... 13

4.2. Physical Properties .......................................................................... 13

4.3. Electrical, Communication & Software .......................................... 13

4.4. Acoustic Properties ......................................................................... 14

II. Installation ......................................................................................................... 15

5. Installing the ROV Sidescan ..................................................................... 16

5.1. Transducer Orientation ................................................................... 16

5.2. Communications ............................................................................. 17

5.3. Power .............................................................................................. 17

6. Installing the Towfish ................................................................................ 19

6.1. Cable and Strain Relief .................................................................. 19

6.2. Communications ............................................................................. 19

6.3. Power .............................................................................................. 20

7. Installing the SK150 .................................................................................. 21

7.1. Cable and Strain Relief .................................................................. 21

7.2. Communications ............................................................................. 21

7.3. Power .............................................................................................. 22

III. Seanet Pro Software Suite ............................................................................... 23

8. Overview of the Seanet Software Suite .................................................... 24

9. Installing Seanet Pro .................................................................................. 25

10. Seanet Pro ................................................................................................ 26

10.1. Basic Operation ............................................................................ 26

10.2. Settings Bar ................................................................................... 27

10.3. Application Tools ......................................................................... 29

10.4. Dynamic Range and Sonar Rx Indicator ...................................... 33

11. Seanet Dumplog ...................................................................................... 35

11.1. Overview of Process ..................................................................... 35

11.2. Application Window ..................................................................... 35

11.3. Options Dialog .............................................................................. 36

IV. Image Tiler Software ....................................................................................... 39

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12. Introduction .............................................................................................. 40

13. Installation ................................................................................................ 41

14. SeaKing Sidescan Image Capture ........................................................... 42

15. Software Functions .................................................................................. 44

15.1. Toolbar .......................................................................................... 44

15.1.1. Project Controls ................................................................. 44

15.1.2. Tile Controls ...................................................................... 46

15.1.3. Zoom .................................................................................. 47

15.1.4. View/Hide Controls ........................................................... 47

15.1.5. Markers .............................................................................. 48

15.1.6. Tile Manipulation .............................................................. 48

15.1.7. Image Export Area ............................................................ 49

15.2. Moving tiles .................................................................................. 50

15.3. Rotating tiles ................................................................................. 50

15.4. Mosaic of Tiles ............................................................................. 51

15.5. Information Dialogs ...................................................................... 52

15.6. Tile List Dialog ............................................................................ 52

15.7. Using Markers .............................................................................. 54

16. Creating the Mosaic Image ..................................................................... 56

16.1. Overview of Process ..................................................................... 56

16.2. Create the Background Chart ....................................................... 57

16.2.1. Image with World File ...................................................... 58

16.2.2. Image with Manual Positional Data .................................. 59

16.2.3. Blank Chart ........................................................................ 60

16.2.4. Co-ordinate System ........................................................... 60

16.3. Add Image Tiles ........................................................................... 61

16.4. Manipulate Image Tiles ................................................................ 61

16.5. Save the Project ............................................................................ 61

16.6. Exporting the completed mosaic as an image .............................. 62

17. Supported File Formats ........................................................................... 64

17.1. For Loading Tiles ......................................................................... 64

17.2. Saving Images or Mosaics ............................................................ 64

17.3. Project Files .................................................................................. 65

17.4. Marker Files .................................................................................. 65

18. Example: Using Sidescan Image Tiles .................................................... 66

V. Service and Maintenance .................................................................................. 68

19. Maintenance ............................................................................................. 69

19.1. After each use of the equipment .................................................. 69

19.2. Regular maintenance .................................................................... 69

19.3. Storage of Equipment ................................................................... 69

19.4. Software Maintenance .................................................................. 70

20. Troubleshooting ............................................................................................... 71

A. ARCNET Termination ...................................................................................... 72

B. CHIRP Signal Processing ................................................................................. 73

C. Networking COMv6 Devices ........................................................................... 75

D. Marker Files ...................................................................................................... 79

Glossary .................................................................................................................. 82

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0374-SOM-00013, Issue: 01

Help & Support

First please read this manual thoroughly (particularly the Troubleshooting section, if present). If a warranty is applicable, further details can be found in a Warranty Statement at the end of the manual.

Tritech International Ltd can be contacted as follows:

Mail

Tritech International Ltd

Peregrine Road Westhill Business Park Westhill, Aberdeenshire AB32 6JL, UK

Telephone ++44(0)1224 744 111

Fax ++44(0)1224 741 771

Email support@tritech.co.uk

Website www.tritech.co.uk

Prior to contacting Tritech International Ltd please ensure that the following is available:

The Serial Numbers of the product and any Tritech International Ltd equipment connected directly or indirectly to it.

2. Software or firmware revision numbers.

3. A clear fault description.

4. Details of any remedial action implemented.

Contamination

If the product has been used in a contaminated or hazardous environment you must de-contaminate the product and report any hazards prior to returning the unit for repair. Under no circumstances should a product be

returned that is contaminated with radioactive material.

The name of the organisation which purchased the system is held on record at Tritech International Ltd and details of new software or hardware packages will be announced at regular intervals. This manual may not detail every aspect of operation and for the latest revision of the manual please refer to www.tritech.co.uk

Tritech International Ltd can only undertake to provide software support of systems loaded with the software in accordance with the instructions given in this manual. It is the customer's responsibility to ensure the compatibility of any other package they choose to use.

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0374-SOM-00013, Issue: 01

Warning Symbols

Throughout this manual the following symbols may be used where applicable to denote any particular hazards or areas which should be given special attention:

Note

This symbol highlights anything which would be of particular interest to the reader or provides extra information outside of the current topic.

Important

When this is shown there is potential to cause harm to the device due to static discharge. The components should not be handled without appropriate protection to prevent such a discharge occurring.

Caution

This highlights areas where extra care is needed to ensure that certain delicate components are not damaged.

Warning

DANGER OF INJURY TO SELF OR OTHERS

Where this symbol is present there is a serious risk of injury or loss of life. Care should be taken to follow the instructions correctly and also conduct a separate Risk Assessment prior to commencing work.

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1. Introduction

The SeaKing Sidescan family of sonars provide various methods for obtaining survey sonar data. The two Towfish and SK150 are both designed to be towed behind a vessel as it navigates survey lines, while the ROV mounted device is designed to be fitted to a remotely operated vehicle which is then used to perform the survey.

Electrically and acoustically the devices are very similar, the ROV model is merely shipped without a hydrodynamic tube and in three components (left/right transducer and electronics pod). The SK150 is a specially designed Towfish that can withstand higher pressures found in deeper water. Communication between the surface computer and the devices can be via RS232, RS485 or ARCNET protocols. The ROV mounted device can be combined with the Tritech International Ltd Subsea Junction Box which will allow other devices, such as the SeaKing or Hammerhead Sonar to be used on the same vehicle.

All three devices are controlled using the Tritech International Ltd Seanet Pro control and display program and are capable of exporting to a variety of industry standard formats for use in post-processing survey packages. It is also possible to use the data in the Tritech International Ltd Sonar Image Tiler program in order to build up a complete picture of a survey site.

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Part I

Specification

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2. SeaKing ROV Sidescan

2.1. Dimensions of Electronics Pod

Power & Communications

134 168

Ø110

Ø99

Transducer 1 and 2

Not to scale, dimensions in mm.

2.2. Dimensions of Transducers

Not to scale, dimensions in mm.

SIDE VIEW

TOP VIEW

side mounting holes

suit M6x1 screw 6.3mm through

top mounting holes (x4) to suit M6x1 6.3mm through

counterbored 10mm to 7mm

500

2.3. Physical Properties

Property Electronics Pod Transducers

Weight in air 2.5kg 1.4kg (each)

Weight in water 1.6kg 0.54kg (each)

Depth rating 4000m

Connector Tritech 6-pin waterblock

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2.4. Electrical, Communication & Software

Power requirement 20 - 36V DC at 12VA

Communication protocols ARCNET, RS232

Communication rates

ARCNET: 156kbit·s-1, 78kbit·s

-1

RS232: 115.2kBd

Software Tritech Seanet Pro or low level direct command

control

Data log format Tritech V4Log as standard

Export to XTF, TIFF, GeoTIFF and Google Earth KMZ via converter

2.5. Acoustic Properties

Frequency 325kHz 675kHz

Beamwidth 30° vertical, 1° horizontal 30° vertical, 0.5° horizontal

Maximum range 200m 100m

Pulse length 400μs 200μs

Source level 200dB re 1μPa at 1m

Sensitivity Better than 2μV rms

Gain control 80dB

Dynamic range 40dB (configurable)

Sample rate 5 - 200μs

Data resolution 4 - 8 bits (configurable)

Note

The ROV Sidescan is supplied as either a Low Frequency or High Frequency sonar and is not switchable.

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3. SeaKing Towfish

3.1. Dimensions

Not to scale, dimensions in mm.

947

Ø63

187

3.2. Physical Properties

Weight in air 7kg

Weight in water 4.1kg

Depth rating 40m

Materials Alumnium body tube and stainless steel nose cone

Operating temperature -10°C to 35°C

Storage temperature -20°C to 50°C

3.3. Electrical, Communication & Software

Power 24V DC at 12VA

Communication ARCNET, RS485 (RS232 optional)

Cable Standard 6.7mm diameter Kevlar re-inforced cable. Supplied

in lengths of 100 and 150 metres.

Software Tritech Seanet Pro

ChesaPeake 'SonarWiz' real-time interface Low level direct access and control

Data log format Tritech V4Log as standard

Export to XTF, TIFF, GeoTIFF and Google Earth KMZ via converter

SeaKing Towfish SeaKing Sidecan Sonars

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3.4. Acoustic Properties

Operating frequency 325kHz 675kHz

Beamwidth 30° vertical, 1.7° horizontal 30° vertical, 1° horizontal

Pulse length 400μs 30° vertical, 1° horizontal

Range 200m 100m

Source level 200dB re 1μPa at 1m

Gain control range 80dB

Display

dynamic range

40dB (configurable)

Data resolution 4 - 8 bits (configurable)

Receiver sensitivity Better than 2μV rms

Note

The SeaKing Towfish is supplied as either a High Frequency or Low Frequency sonar and is not switchable.

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4. SeaKing Towfish SK150

4.1. Dimensions

Not to scale, dimensions in mm.

1160

Ø124

10°

385

4.2. Physical Properties

Weight in air 25.5kg

Weight in water 15.5kg

Depth rating 120m

Materials Polyester powder coated aluminium

Operating temperature -10 to 35°C

Storage temperature -20 to 50°C

Maximum towing speed 5 knots

4.3. Electrical, Communication & Software

Power requirement 36 - 48V DC (300mA at 36V)

Connector Tritech standard 6-pin waterblock

Cable Wire armoured

Software Tritech Seanet Pro or low level direct access and control

Data log format Tritech V4Log as standard

Export to XTF, TIFF, GeoTIFF and Google Earth KMZ via converter

SeaKing Towfish SK150 SeaKing Sidecan Sonars

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4.4. Acoustic Properties

Operating frequency 150kHz

Beamwidth 60° vertical, 1.4° horizontal

Maximum range 350m

Minimum range 0.4m

Range resolution 5 - 300mm

Source level 210dB re 1μPa at 1m

Pulse length 400μs

Bandwidth 40kHz

SeaKing Sidecan Sonars

0374-SOM-00013, Issue: 01

Part II

Installation

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5. Installing the ROV Sidescan

5.1. Transducer Orientation

Caution

Although the sonar is rugged, it should be handled with care, particularly the connector and transducers.

The SeaKing ROV Sidescan sonar comprises two separate transducers which are connected wit interconnect leads to a dual channel electronics pod.

25°

ROV

Figure 5.1. ROV Sidescan Installation Example

The transducers should be mounted at an ideal tilt angle of 25° below horizontal as indicated in Figure 5.1, “ROV Sidescan Installation Example”. This will reduce the length of the blind spot directly below and to each side of the vehicle (i.e., the areas which do not fall within the transmit beam coverage). With a 25° angle the ROV can be flown at a height of approximately 10% of the configured range.

To increase the maximum range the angle can be reduced to 10° and the ROV height above the seabed increased but doing so will increase the size of the blind area underneath the ROV. Targets may be missed if the ROV is flown directly over the top of them.

A guard can be fitted to the ROV to protect from impact damage but this must not overlap the transducer area or it may have an effect on the sonar image.

The electronics pod should be secured by clamping on the cylindrical body. The clamp should be applied centrally to the aluminium body tube and should not be over-tightened. Any metallic clamps should be electrically insulated from the body by means of rubber or plastic strips or mount brackets of at least 3mm thickness and extending at least 3mm beyond the clamp boundary to reduce any galvanic corrosion effect. Non-metallic clamps are preferable and if metallic clamps are used they should be painted or lacquered with at least two or three coatings.

Caution

Avoid any metal alloys containing copper such as brass or bronze.

Installing the ROV Sidescan SeaKing Sidecan Sonars

0374-SOM-00013, Issue: 01

Note

The electronics pod does not need to be installed in a dry area and is rated against water ingress so can be placed anywhere on the ROV.

5.2. Communications

The SeaKing ROV Sidescan electronics pod is fitted with a maximum of four standard Tritech waterblock connectors. Two of these will be labelled PORT and STARBOARD and these should be used to connect to the transducers using a cable that is wired straight through (with a 1 to 1 wiring). The other two ports are MAIN which is for connection to the surface and optionally AUX which is for connecting auxiliary devices such as altimeters, oceanographic sensors and scanning sonars. The AUX port may be blanked off.

The MAIN connector and optional AUX connector are wired as follows:

Tritech Waterblock

Pin Function Cable colour

ARCNET A

RS232 TX

Yellow

ARCNET B

RS232 RX

Blue

3 DC + Red

4 DC - Black

5 RS232 Ground Green

6 Earth/cable shield cable screen

Note

If communicating using the ARCNET protocol it will be necessary to have resistors fitted at each end of the cable. For more details please refer to Appendix A, ARCNET Termination for more information.

5.3. Power

The SeaKing Towfish range of sensors are designed to work over a smoothed DC power supply over the range specified in Chapter 2, SeaKing ROV Sidescan.

Caution

Never try to make the Towfish work over a longer cable by increasing the voltage above the maximum specified, doing so may cause permanent damage.

Installing the ROV Sidescan SeaKing Sidecan Sonars

0374-SOM-00013, Issue: 01

If using a rectified transformer PSU the output must have a filter capacitor of at least 470μF for each head that is being powered. The use of unregulated power supplies is not recommended.

If powering the head down a long lead or umbilical, the maximum recommended loop resistance of the power line must not exceed 10Ω for a single device. If other SeaKing devices are connected via the AUX port in a network then the loop resistance should be 5Ω for two devices and 3Ω for three devices.

If the supply voltage is less than the minimum specified in Chapter 2, SeaKing ROV Sidescan the Sidescan is unlikely to work correctly.

Ground Fault Monitoring Equipment

The power supply within all SeaKing devices includes an electrically isolated DC to DC converter front end with a small capacitive connection made to the sonar chassis. This should not noticeably affect any impressed current Ground Fault Interrupter (GFI) or Residual Current Devices (RCD).

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6. Installing the Towfish

Note

The Towfish is supplied balanced for level flight in water. Do not add to or alter the parts as this may affect the hydrodynamic properties.

6.1. Cable and Strain Relief

Note

In order to have enough cable it is advisable to have at least 3m of cable for every 1m of operating depth. The cable should be re-inforced with Kevlar.

The SeaKing Towfish is fitted with a strain relief mechanism which is located in the tow arm by two cable clamps and attached by wire to the rear section. A side plate is fitted on the tow arm to secure the cable and strain relief in place. The tow arm is connected to the tow bar on the body using a pivot assembly and pivot pin which is designed to shear if the Towfish is subject to impact whilst under way. This will enable the Towfish to be recovered tail first and should prevent it from becoming entangled.

An acetal tail cone is screwed on the rear end which can be unscrewed to enable the removal of the safety wire and pin assembly.

If the fins hit a hard object they are designed to slide out and are secured by an elastic cord which prevents them from being lost. This elastic cord has a loop in one end and the safety wire should be passed through this loop before being secured with the tail cone and pin assembly.

6.2. Communications

The SeaKing Towfish is fitted with a standard Tritech waterblock connector. This is a 6 pin connector and is wired as follows:

Installing the Towfish SeaKing Sidecan Sonars

0374-SOM-00013, Issue: 01

Tritech Waterblock

Pin Function Cable colour

ARCNET A

RS232 TX

Yellow

ARCNET B

RS232 RX

Blue

3 DC + Red

4 DC - Black

5 RS232 Ground Green

6 Earth/cable shield cable screen

Note

6.3. Power

The SeaKing Towfish range of sensors are designed to work over a smoothed DC power supply over the range specified in Chapter 3, SeaKing Towfish.

Caution

Never try to make the Towfish work over a longer cable by increasing the voltage above the maximum specified, doing so may cause permanent damage.

If using a rectified transformer PSU the output must have a filter capacitor of at least 470μF for each head that is being powered. The use of unregulated power supplies is not recommended.

If powering the head down a long lead or umbilical, the maximum recommended loop resistance of the power line must not exceed 10Ω.

If the supply voltage is less than the minimum specified in Chapter 3, SeaKing Towfish the Towfish is unlikely to work correctly.

Ground Fault Monitoring Equipment

SeaKing Sidecan Sonars

0374-SOM-00013, Issue: 01

7. Installing the SK150

Note

The SK150 is supplied balanced for level flight in water. Do not add to or alter the parts as this may affect the hydrodynamic properties.

7.1. Cable and Strain Relief

Note

In order to have enough cable it is advisable to have at least 3m of cable for every 1m of operating depth. The cable should be re-inforced with Kevlar.

The main towing point is secured to the body with nylon fasteners which will shear when subjected to excessive pulling pressure. Also the bow pin on the tow cable mounting shackle will shear when excessive pulling pressure is applied.

If the fins hit a hard object they will break off and can be easily replaced on recovery of the SK150.

7.2. Communications

The SeaKing Towfish is fitted with a standard Tritech waterblock connector. This is a 6 pin connector and is wired as follows:

Tritech Waterblock

Pin Function Cable colour

ARCNET A

RS232 TX

Yellow

ARCNET B

RS232 RX

Blue

3 DC + Red

4 DC - Black

5 RS232 Ground Green

6 Earth/cable shield cable screen

Note

Installing the SK150 SeaKing Sidecan Sonars

0374-SOM-00013, Issue: 01

7.3. Power

The SeaKing Towfish range of sensors are designed to work over a smoothed DC power supply over the range specified in Chapter 4, SeaKing Towfish SK150.

Caution

Never try to make the Towfish work over a longer cable by increasing the voltage above the maximum specified, doing so may cause permanent damage.

If using a rectified transformer PSU the output must have a filter capacitor of at least 470μF for each head that is being powered. The use of unregulated power supplies is not recommended.

If powering the head down a long lead or umbilical, the maximum recommended loop resistance of the power line must not exceed 10Ω.

If the supply voltage is less than the minimum specified in Chapter 4, SeaKing Towfish SK150 the SK150 is unlikely to work correctly.

Ground Fault Monitoring Equipment

SeaKing Sidecan Sonars

0374-SOM-00013, Issue: 01

Part III

Seanet Pro Software Suite

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0374-SOM-00013, Issue: 01

8. Overview of the Seanet Software Suite

The Seanet Pro software suite is a set of programs which enables complete control of all the Tritech International Ltd sonar equipment. The programs are available individually from www.tritech.co.uk.

Seanet Pro This is the main program for controlling and displaying the sonar

data. The program allows data from multiple sources, such as GPS, altimeter, scanning and side-scan sonars, to be displayed on one screen. It is also possible to log the sonar data and store it on the computer hard drive.

Seanet Setup This is included as part of Seanet Pro and it is not possible to install

it separately. Using this program it is possible to re-configure the sonar by changing communication protocols or baud rates. It is also possible to choose which serial port the sonar is connected to if there are multiple ports on the computer.

Seanet DumpLog

In order to process SeaKing Sidescan log files it may be necessary to convert them into another format and the Seanet DumpLog utility is designed to allow conversion between the standard Seanet Pro (.v4log) format and other industry standard formats.

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0374-SOM-00013, Issue: 01

9. Installing Seanet Pro

Note

The hardware must not be connected to the PC prior to or during software installation.

If any Seanet software is already installed on the PC this must be removed correctly using Windows Control Panel - Add or Remove Programs (or Programs and Features in Windows 7) prior to starting the software installation.

Note

The latest version of Seanet Pro can be obtained from www.tritech.co.uk

Insert the Seanet Pro installation CD into the PC CD-ROM drive - if autorun is enabled a dialog will appear with installation options. If autorun is disabled then run the Setup.exe from the CD.

When the installation program starts, click Next to continue.

Read the license agreement and if you agree to its terms select the YES option and click Next to continue.

Confirm the installation destination directory (by default C:\Program Files \SeanetV2 but if you wish to change this click the browse button and select an alternative directory), click Next to continue.

Installation will then copy files onto your computer and make entries in the Windows Registry, this process may take several minutes. If any anti-spyware software is running this may warn you that registry changes are being made, allow any changes to be made if prompted. Once files are copied you will be prompted to restart the PC (if you wish to defer the restart select No ), click Finish to continue.

If the installation has been successful two new icons will have been created on the desktop for Seanet Pro and Seanet Setup.

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10. Seanet Pro

10.1. Basic Operation

The SeaKing Sidescan sonars have 2 transducers fitted in a port and starboard arrangement. The display software can display both or either one of these channels. The transducers are fired in a "ping-pong" mode, i.e., the port transducer fires and receives a return signal and then the starboard transducer fires (if using a modern DST sonar the transducers can be configured to fire simultaneously using the Sidescan option under Application Tools).

The Sidescan echo return data may be displayed with time marks and text labelling and the software has the option to output the data to a thermal plotter via a parallel port interface.

To set up Seanet Pro for use with a SeaKing Sidescan first launch Seanet Pro and then navigate to the Applications menu and select Application Wizard. In the configuration wizard which presents itself, select Add Application then click Next and choose Sidescan from the list. The rest of the wizard allows customisation of the layout.

Once the software is configured and data is being received the display will be built up as the sonar is moved forward through the water. A typical display is shown in Figure 10.1, “Sidescan Sonar Data in Seanet Pro”

Seanet Pro SeaKing Sidecan Sonars

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Figure 10.1. Sidescan Sonar Data in Seanet Pro

The main areas of the display are:

1. Display Header - this part of the screen is used for system/software

identification.

2. Menu Bar - this is where system set-up functions can be accessed.

3. Settings Bar - this is where the Sidescan can be controlled and configured.

The settings bar is on top of every display window for each device that is connected to the system. It includes a Tools Setup button, status indicator (pause/go) and RAT dials and buttons

4. Status Bar - this part of the screen is used to display system status information,

logging status/progress and job specific information.

5. Sensor Display Area - this part of the screen is where the main Sidescan

data is displayed. Other pertinent data such as range scale, cursor and status messages pertaining to the Sidescan may also be displayed within this area

10.2. Settings Bar

These controls are displayed on the Sonar Settings bar. Each button has a function on the RAT as described:

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Note

On the RAT, F1 - F3 and F5 - F7 are not used.

Sonar Gain (C1, C4) This sets the sonar receive gain as required - typically

this is around 20% but can be varied according to water and target conditions.

Contrast (C2, C5) This sets the display contrast between hard and soft

targets. It can help to find small features in a generally featureless situation or exclude clutter from a heavily featured seabed.

Range (C3) This sets the maximum range the sonar will scan.

Long ranges are scanned more slowly than short ranges due to the limit imposed by the velocity of sound in water (and may require a slower vehicle speed if the the Sidescan is being towed).

Resolution (F4) Resolution toggles through 4 preset sampling periods

over the pulsed range.

Lo resolution produces the least samples and gives the lowest resolution. The number of samples is increased from Med, Hi through to Ult. Usually a Lo or Med resolution are used for very fast tow speeds where more scan-line updates are required giving coarser detail. Hi or Ult should be used for detailed examination of targets at a slower tow-speed.

Frequency On the sidescan sonars this is for information only and

cannot be changed.

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10.3. Application Tools

Cursor

Adds the cursor position panel to the sonar display, displays the Range and Time.

Move the mouse pointer over the Sidescan waterfall display to update the cursor position giving Range to pointer and Time of scan-line that the pointer is positioned over.

Note

If the system has real-time GPS position and heading data input, the panel will extend to additionally display the target coordinates.

Display

Controls all the display options.

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Grid Display the set number of range lines.

Scroll Zoom the waterfall plot on the time axis (i.e., accommodates different

vehicle speeds). Auto auto-adjust scroll from incoming vehicle speed data.

NDetects Number of detects.

Event On

Toggle display event on/off.

Line Toggle event line on/off.

Text Toggle event text on/off.

Event Interval

Set a time interval of 1-60s between events. This is not applicable to "Manual Text" events.

Event Text

Text1 is displayed on the left and Text2 is displayed on the right. Choose from:

• None (no event text displayed)

• PC DateTime (current date and time from the control computer)

• Manual Text (enter text via the text box and click the Annotate

button)

• Remote Text (from a serial "Aux" device configured through the

Utilities menu and Aux Device)

• GPS E/N (Easting/Northing from a GPS)

• GPS Lat/Lon (Latitude/Longitude from a GPS)

• GPS UTC Time

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Position

Sets the lay-back offset (in metres) which is the distance between the Sidescan sonar and reference datum (i.e., GPS receiver).

Note

This is only applicable to towed Sidescan sonars, the Towfish and SK150.

Setup

Sets various options to control the display of the Sidescan data.

8 bit Usually checked. Selects the intensity sampling of sonar data, if un-

checked the intensity will be set at 4 bit.

Detects Paint the leading edge of strong targets on the screen, used to

emphasise sub-bottom layers.

Scrn Lock Locks the number of range "bins" sampled to the screen resolution.

This over-rides the Resolution (F4) control.

Lockout Sets a minimum lockout range for the detects (always in metres).

Units Waterfall display range units (metres, feet, fathoms or yards).

Auto Dynamic Range

This will auto adjust the display contrast and sensitivity whilst the Sidescan is running. Auto adjustment occurs periodically.

Plotter

This is for printout to a parallel port EPC or Alden thermal plotter.

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EPC/ Alden

Select the desired printer and then tick the Enabled tick-box to open the parallel port connection.

Alden Setup

When Alden is selected this button will become active. Click this button to setup the Alden interface.

Negative inverts greyscale output. Output allows the left, right or both channels to be chosen as the output. Line Repeat stretches the printout by repeating line printouts (0 = off).

Sidescan

This is where the Sidescan channel settings are configured.

Interleaved Scan This button becomes enabled when a DST Sidescan is

connected. The DST Sidescan has capability to fire both channels at the same time (as opposed to in "ping-pong" mode) and this control enables simultaneous firing.

Slope Applies a Time Variable Gain adjustment to the received

signal returns to account for through-water attenuation of the transmit pulse.

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Note

When the Interleaved Scan mode is enabled, the DST Sidescan reverts to "ping-ping" operation as opposed to "ping-pong". This doubles the quantity of data being transmitted to the surface with a larger overhead on the Sidescan plotting function. To run in this mode a modern computer (at least a Pentium 4) is required to cop with the increase in data. If the CPU activity reaches 100% it will be necessary to disable Interleaved Scan.

10.4. Dynamic Range and Sonar Rx Indicator

The dynamic range bar is the A/D sample window (with 64-colour mapping) for the Sonar receive signal (which extends from 0 to 80dB).

To the right of the dynamic range bar is the Sonar receive signal strength indicator (Yellow = Average amplitude over scan-line, Red = Maximum amplitude echo for scan-line).

Normally the sampling window should not need to be adjusted from its default position (as shown on the left). However, if used properly, adjusting the sample window can produce better quality imaging.

The dynamic range bar can be adjusted to change Sonar display contrast and sensitivity. Adjustment is made using the left and right mouse buttons.

Contrast adjustment Right-click on the bar and whilst holding

down the right button, move the mouse up/ down to increase/decrease the size of the bar. The sampling window can be any size between a range of 9 - 25dB. Decrease the size of the sampling window to increase the sonar display contrast. Ideally the control should be set somewhere in the centre of the allowed range (16 - 18 dB) to give the best results under most conditions. Select a high value to reduce the contrast of the sonar display.

Sensitivity adjustment Left-click on the bar and whilst holding

down the left button, move the mouse up/ down to decrease/increase the Sensitivity of the Sonar receiver. Decreasing the Sensitivity will produce a more saturated display with greater weak-return content. Increasing the Sensitivity will omit

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background noise and low level returns seen at the receiver

The sonar receiver will accept a return signal in the region of 0 - 80dB. The dynamic range controls are used to adjust the position of a sampling window within the 0-80dB dynamic range band of the receive signal. An idealised representation of the sample window is shown:

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11. Seanet Dumplog

Note

The latest version of Seanet Dumplog is available from

www.tritech.co.uk. This section applies to version 2.20 of the software.

11.1. Overview of Process

Seanet Dumplog is a tool for converting Tritech International Ltd standard Seanet log files with the filename extension of .v4log into other industry standard formats. The process of conversion is as follows:

1. Acquire a log file from Seanet Pro.

2. Launch Seanet Dumplog and load the previously recorded log file.

3. Select the sonar type that has been used (in this case Sidescan) and if any GPS data is present.

4. Select the desired output image format (e.g., TIFF or GeoTIFF).

5. Click on the Options button and configure any specific options for the output, such as the colour to use.

6. Click on the Convert File(s) button and the process will start. After the conversion a prompt will appear to name and choose the location of the save file.

11.2. Application Window

The Seanet Dumplog utility is a simple application and most of the functions are available on a single screen as shown below.

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11.3. Options Dialog

For advanced configuration and control of the output it is sometimes necessary to use the Options dialog. This is split into six tabs with each tab relating to the different output formats available.

General

The option relevent to the sidescan sonar on this tab is Invert Chan (L<>R). This will swap the Port and Starboard channels over to create a mirror image if desired.

The Sensitivity Level can also be altered to compensate for a very noisy sonar scan which contains many returns.

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SGY

This tab is not relevant to Sidescan data.

CSV

The GPS Format drop-down list can be used to configure GPS data (if it is present in the log file). In the list Raw Data outputs the GPS data as it was recorded and UTC, E, N outputs in UTC format with Easting and Northing position.

TIF/GEOTIFF

These are the options for configuring the output of the Sidescan as images.

The selections made here will also determine how the KMZ output is formatted as well.

XYZ

This tab is not relevant to Sidescan data.

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KMZ

For output to Google Earth KMZ format use the TIFF/GEOTIFF tab to control the image background colour and palette.

Use this tab to choose the image resolution.

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Part IV

Image Tiler Software

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12. Introduction

The Tritech Sonar Image Tiler is designed to allow sonar images to be stitched together into a single larger image or mosaic. This allows mapping or surveying work to build up a complete picture of the seafloor in important areas such as harbour floors, wreck sites or around underwater structures such as bridge and platform supports.

Note

This manual applies to software version 1.3

Hardware & Software Requirements

•

A laptop, PC or SCU running Seanet Pro OR a computer running the offline DumpLog utility and a previously recorded Sidescan log file.

• Positional data either from an external GPS/USBL linked into Seanet Pro or from

a manually entered World Position for the sonar installation.

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13. Installation

The installer file for the Sonar Image Tiler can be found on the Hammerhead Installation CD or downloaded from: www.tritech.co.uk

The installation CD will autorun on disc insertion, select the following button to install the software:

If installing from the Internet an executable file called ImageTilerSetup.exe will be downloaded. Run this file and follow the on-screen instructions.

Upon installation a program icon will be created on the Windows desktop and a Tritech Image Tiler folder will be added to the Windows Start menu.

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14. SeaKing Sidescan Image Capture

The Sidescan and GPS data first has to be recorded into a log file (.v4log) using Seanet Pro. This log file is then opened in the DumpLog offline utility program and a GeoTiff output is created. This GeoTiff output will also contain a World File assuming that there is valid GPS data within the log file.

For the latest version of the DumpLog utility please visit: www.tritech.co.uk

Run DumpLog and click on Open File(s)

Select the log file or files that are to be converted.

Select the GEOTIFF output format and then tick the Sidescan and GPS device boxes as shown below:

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Note

If the indicators next to the Sidescan or GPS boxes are not illuminated red after opening the log file it indicates that there is no matching data. If this is the case it will not be possible to create a GeoTiff and World File output for use with the Image Tiler.

There are several TIF and GeoTiff settings that can be altered by clicking on Options and selecting the TIF/GEOTIFF tab page.

The main settings are for a Colour Scheme to be applied to the output sidescan imagery and a choice of methods to apply heading/course correction to the output file. The Beam Width sets the width of each scan line which can help with gaps that may occur, particularly when cornering.

Once setup is complete click on Convert File(s) to create the output. This will create .TIF (GeoTiff image) and .TFW (World File) files which can then be imported into the Sonar Image Tiler.

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15. Software Functions

15.1. Toolbar

Import chart Export as image Save project Load project Clear project Add tile Delete all tiles Reset all tiles Resize tile Create mosaic Save mosaic Zoom in Fit to screen Zoom out Toggle coordinates dialog Toggle coordinate system dialog Toggle tile list dialog Toggle chart Show markers Move marker Pan tool Erase tool Area erase tool Remove tile background Export area

15.1.1. Project Controls

Import/Create Chart

For creating a blank chart or importing a previously created chart. For more information on this function please see Section 16.2, “Create the Background Chart”.

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Export As Image

If an area is selected this button will export the selected area. If no area is selected the whole chart will be exported.

For details of the supported file format please refer to: Section 17.2, “Saving Images or Mosaics”.

Note

The markers will be embedded into the image file and if the image is loaded again it will no longer be able to modify or hide them. If exporting the image to use again as a chart the markers should first be hidden (see Section 15.7, “Using Markers”).

Save Project

The first time this is pressed it opens a dialog to name and then save the current state of the chart, tiles and markers as an XML file. Using this option allows the project to be loaded later and the markers or tiles moved or hidden.

Subsequent presses of the button will not prompt for a filename and instead save over the existing project - to save under a different name navigate to the File menu and

select Save Project As....

Note

If the tiles have been moved or rotated away from their original positions it will no longer be possible to restore them after the Project has been saved, i.e., the new "original" position which they will be returned to when they are "reset" will be the position which they were in when the Save Project button was pressed.

Load Project

For loading a previously saved Project file. The files are only generated by the Sonar Image Tiler and are in XML format.

For details of the supported file format please refer to: Section 17.3, “Project Files”.

Clear Project

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Removes any loaded data and clears the workspace. Any unsaved data will be lost.

15.1.2. Tile Controls

Add Tile

Opens a dialog to load an image tile. Image tiles must be in the correct format and have an associated world file.

For details of the supported file format please refer to: Section 17.1, “For Loading Tiles”.

Delete All Tiles

Removes all the tiles from the chart. Any unsaved changes will be lost

Note

To delete a tile individually use the Tile List as detailed in Section 15.6, “Tile List Dialog”.

Reset All Tiles

Resets all the tiles using the position, orientation and size from when they were first loaded.

If the tiles were loaded as part of a project then they will be reset to the original state that they were when the project was saved.

Note

To reset a tile individually use the Tile List as detailed in Section 15.6, “Tile List Dialog”.

Resize Tile

Tiles can be resized individually using this tool. When the tool is enabled each tile will show a thin red outline with anchors at the corners and side midpoints. The

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mouse pointer will change to arrows indicating the available resize direction when it is positioned above the resize points. Click, hold and drag to resize the tile. The corner anchors maintain aspect ratio while it is resized whereas the side anchors allow the image to be stretched.

Create Mosaic

This will stitch all the visible tiles together into a single image. If only some of the tiles are to be included the remaining ones should be hidden from view using the Tile List as detailed in Section 15.6, “Tile List Dialog”.

Save Mosaic

Saves the newly created mosaic as an image with an accompanying world file which can then be loaded as a tile for future Projects.

Using the Save Mosaic function has the advantage over Create Mosaic in that it does not alter the tiles within the project so they can still be modified if desired. The newly created mosaic is in a completely separate file.

For details of the supported file format please refer to: Section 17.2, “Saving Images or Mosaics”.

15.1.3. Zoom

The zoom controls allow the user to Zoom In on an area of the screen by using the

button or by scrolling the mouse wheel forward.

Similarly, zooming out can be accomplished using the Zoom Out button or scrolling the mouse wheel backwards.

The view can be reset so as the chart fits into the window by pressing the Fit To Screen button

15.1.4. View/Hide Controls

These controls are the same as those found in the View menu and allow the different dialogs to be shown or hidden from the workspace.

The background chart can be hidden to allow better viewing of the individual tiles by selecting the View/Hide Chart button:

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For more detail on the functionality of the dialogs refer to Section 15.5, “Information Dialogs” and Section 15.6, “Tile List Dialog”.

15.1.5. Markers

Using these buttons the markers can be shown, hidden or moved. For a full description of the use of markers see Section 15.7, “Using Markers”

15.1.6. Tile Manipulation

Pan Tool

The pan tool is the default operation and allows the current viewpoint to be moved around by clicking and holding the left mouse button - useful if zoomed in or using a very large chart.

When this tool is selected and the mouse pointer is hovered over the tile handles the functionality will change to that of move a single tile or rotate the tile (depending on where the mouse pointer is located).

Note

This tool does not alter the position of the chart - it simply changes the visible portion on the screen.

Erase Tool

Note

This action cannot be undone. To restore the original tile the tile has to be deleted and then added afresh.

This tool allows parts of the sonar tile to be removed manually as if using an eraser. To remove a section of sonar tile select this tool then click and drag the left mouse button over the desired area. When this tool is active the mouse cursor should change to an eraser.

If multiple tiles are overlapping the erase tool will work on the uppermost tile only but if a portion is already erased the eraser will start to erase the tile below as well. To avoid accidentially erasing the wrong tile, it is recommended that the tiles that are not being worked on are disabled or hidden using the Tile List (see Section 15.6, “Tile List Dialog”).

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Area Erase Tool

Note

This action cannot be undone. To restore the original tile the tile has to be deleted and then added afresh.

This tool erases polygonal-shaped sections from the sonar image tile. To use it select the tool then click (and release) on the sonar tile, move the mouse and click again to add another point (the points will be joined by a red line). Keep adding points until the desired shape has been constructed and then double-click to close the area (i.e., the last added point will be joined to the first point with a straight line). When the area is closed the polygon that is created will be automatically deleted from the tile and the red outline will also disappear. While this tool is active the mouse cursor will change to a cross-hair with polygon shape.

All visible tiles that intersect with the defined polygon will have a section deleted. To make sure that some tiles are preserved, first hide them from view - see Section 15.6, “Tile List Dialog”.

Crop Background

Note

This action cannot be undone. To reset the tile, it must be deleted and added again as if it is new.

To control the amount of sonar data displayed in a tile the automatic background removal tool uses an intelligent algorithm to determine unwanted sections and remove them from the tile. Unwanted background pieces are those that are typically around the edge of the sonar scan and do not add any detail to the images. In general, acoustic shadows around areas of high intensity should be kept as they add detail and context to the image.

15.1.7. Image Export Area

The Image Export Area selection tool enables restricted areas of the workspace to be exported to an image file. The mouse pointer will change to a cross-hair for more accurate selection. To use, simply draw a box around the area to be exported and then

press the Export As Image button ( )

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Note

Only when this button is enabled will the selection be used as the export area, otherwise the entire chart will be used.

15.2. Moving tiles

The Pan Tool button has to be selected for this function to work.

When the mouse pointer is over the centre of the tile it will change to a hand icon. Hold down the mouse button to drag the tile and position it correctly.

15.3. Rotating tiles

The Pan Tool button has to be selected for this function to work.

A tile can be rotated by selecting and moving the rotation lever (see Figure Figure 15.1, “Rotating the Tile”). The mouse pointer will change to show a hand with rotation arrows when it is positioned above the end of the lever. Holding the mouse button down and dragging in a circular motion will rotate the tile:

Figure 15.1. Rotating the Tile

The amount of rotation will be displayed in the Tile List panel (which can be displayed using the View menu and selecting Tile List).

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The colour of the rotate handle can be changed by navigating to the Tools menu and selecting Options

15.4. Mosaic of Tiles

To create a mosaic of tiles it will be necessary to have multiple tiles together within a single geographic region. It will not be possible to create a mosaic if the tiles are very far apart, likely as a result of having an incorrect or corrupt world file which results in their incorrect placement.

Creating a mosaic is a simple process, first arrange the tiles as desired and hide tiles that are not going to be included in the final mosaic, then press the mosaic button

on the toolbar ( ) which will start the mosaicking process. An example of this is presented in Figure 15.2, “Mosaicking Tiles”.

Note

The mosaicking process is irreversible and will result in a new tile created which cannot be split into the original tiles. To restore the original tiles they will have to be re-loaded.

Figure 15.2. Mosaicking Tiles

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Note

If Save Mosaic is pressed instead the output will not be on the screen but to a file so a file chooser dialog will present itself.

15.5. Information Dialogs

There are also three information panels accessible from the toolbar or the View menu: the tile list; mouse position; and the coordinate system used. Both the tile list and the mouse view display the position of tile centres or mouse pointer, respectively, using the selected coordinate system.

Coordinate System

The Coordinate System display can be viewed and controlled by selecting the button or using the View menu and select Coordinate System option.

This allows the user to choose between using Decimal Degree, Degrees and

Decimal Minutes, Degrees, Minutes and Seconds and Universal Transverse Mercator (UTM). Selecting one of these options automatically

updates the display in the both the Mouse Position and Tile List display panels.

Mouse Coordinates

The Mouse Coordinates display is also controlled from the View menu and View button collection . It shows the mouse position in the context of the chosen

coordinate system.

15.6. Tile List Dialog

The Tile List panel can be made visible using the View menu and selecting the Tile List option.

Alternatively the Tile List can also be viewed using the button: .

Action on Multiple Tiles

By holding down the shift key on the keyboard it is possible to select multiple tiles in the Tile List and move them up/down the layers together, show/hide them as a group or delete/reset multiple tiles in one go.

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Saving the tile will only work on one tile at a time.

Layering tiles

Layering the tiles determines the order in which they are displayed, i.e., tile 1 is displayed in front of tile 2. The order can be changed by moving tiles up and down in this list, either as individual tiles or in groups.

Note

If centre marks or rotation handles obscure one another interaction will occur using the lowest numbered (corresponding to the topmost) tile so it may be necessary to re-order the tiles to gain access to the handles.

Click on the row containing a tile to highlight it and then press either the UP or DOWN arrow to bring the image forward or backward on the display by one layer.

Multiple tiles can be moved in one go by selecting each one and holding down the control key on the keyboard (or by selecting a span using the shift key). Once selected the tiles can be dragged as a group by holding down the mouse button and moving up or down the list to re-order them.

The tiles will be automatically renumbered with the lowest number being the first one displayed.

The tiles can also be controlled using a menu that is accessible by clicking on the tile entry in the list with the right mouse button. Using this method the tile can also be moved immediately to the front or the back of the display stack.

Save Selected Tile

Saving a tile will export it with a new world file so that any changes that have been made to the position or orientation can be preserved.

Delete Selected Tiles

Deleting a tile will permanently remove it from the display. Any changes made to it will be lost.

If multiple tiles are selected when this button is pressed they will all be deleted.

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Reset Selected Tiles

Resetting a tile changes the tile location, orientation and size to the coordinates and rotation value contained in the world file that was originally used to load the tile. Any subsequent movements or rotations that have been made are lost.

If multiple tiles are selected when this button is pressed they will all be reset.

Note

If a project has been loaded the tile will be reset to the orientation when the project was loaded. The process of saving the chart and tiles as a project

removes the original tile data so the only way to restore the original tile would be to delete it and reload it.

Show/Hide Selected Tiles

Tiles are hidden by de-selecting the check box to left of the tile number.

If multiple tiles are selected when this button is pressed they will all be shown/hidden.

15.7. Using Markers

The Image Tiler has the ability to import a marker file which has been saved from Seanet Pro (marker files have the extension ".mrk") or from a CSV text file (full details of the marker files are in Appendix D, Marker Files).

First create the marker file from the chart in the MicronNav application in Seanet Pro. Then open the marker file by navigating to Import Marker File from the Tools menu.

The imported markers will be overlayed on top of the chart:

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The positions of the markers is shown next to the location. Markers can be hidden

using the button on the toolbar: .

To move a marker first select the move marker button ( ) and then click on the marker and drag it to the new location.

Note

If markers are displayed and Export as Image is selected they will be merged with the background. If the chart is to be used again it will not be possible to move or remove the markers. For this functionality the chart should be saved without the markers or with them hidden. If Save Project is selected the chart, tiles and markers are all saved as individual entities and can be interacted with as normal.

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16. Creating the Mosaic Image

Figure 16.1. Completed Mosaic

A mosaic as shown in Figure Figure 16.1, “Completed Mosaic” can be created with the Sonar Image Tiler using a background chart, and sonar image tiles with their associated world files. The user must first set a background to place the image tiles. This background is called a "chart"; although if an actual survey chart is not available a blank canvas can be used. There is also the option to use the first added tile as a reference. All image tiles and background chart or blank canvas require georeferencing. This is done during the creation of the chart by entering Position Co-ordinates for the top-left corner and a chart Width and Height.

With a background chart in place the sonar image tiles can then be loaded and any position or rotation corrections made. The entire chart and tiles, or a selected area, can be exported as an image file and a (separate) world file.

This chapter is organised into sections explaining the process of creating a mosaic, the tools available to the user, and also exporting an image or saving the project.

Note

Load Project allows a previously created chart, collection of tiles and markers to be loaded for further editing or for selecting an area to be exported as a bitmap.

16.1. Overview of Process

Prior to starting the mosaic process it is necessary to obtain the following:

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• An image with GPS data in an associated world file to use as a background. Or

appropriate GPS coordinates and geographical dimensions sufficient to encompass all of the sonar image tiles if creating the chart manually.

• A set of sonar image tiles from a Seanet Pro session which include GPS data in

accompanying world files.

Given data already created using Seanet Pro the process for tiling images into a mosaic is as follows:

1. Create a chart: either from an image, import a previously created chart or create a blank chart from GPS data.

2. Load sonar image tiles onto the chart.

3. Manipulate the image tiles to the correct position (if required).

4. Either export the resulting mosaic as a bitmap (with world data) or save as a project (containing a chart and a collection of tiles) to work on again later.

16.2. Create the Background Chart

The Sonar Image Tiler starts with a blank screen:

First create a chart background onto which the sonar image tiles will be placed. If Seanet Pro is running on the PC and has a chart configured as part of its Nav application then you can select it using the Files menu and Open Seanet Chart option. If no Seanet chart is available click on the Import/Create Chart button

to set up a new chart background.

Note

It is also possible to use the first tile as the chart background - see below for the procedure for adding tiles. This tile cannot be moved or rotated and acts as the fixed reference point for other tiles.

In the Add Chart dialog box there are three options for adding or creating a chart. The user can select to use an image with associated world file; an image with manually

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entered position and scale; or a blank chart with manually entered position data. These options are explained further in the following sections.

16.2.1. Image with World File

Select Import World File for the Open World File dialog and select the appropriate world file. The format of the world file can be either .bpw (bitmap), .jgw (jpeg), .tfw (tiff) or .wld (generic/CAD).

The world file format for x and y co-ordinates can either be in Eastings/Northings (E/ N) or Longitude/Latitude (L/L). If co-ordinates are in E/N then a Zone will need to be entered and a reference Ellipsoid selected (for definition of latitude, longitude and elevation).

Verify chart parameters are correct and click OK to confirm and load this chart onto the display.

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16.2.2. Image with Manual Positional Data

First, select Open Image button to bring up the Open Chart dialog and select the required chart image. The image format can either be .bmp (bitmap), .jpg (jpeg) or .tif (tiff).

Note

Where an associated world file (matching name) is detected in the same folder as the selected image the chart parameters will automatically be loaded.

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Next, enter the Point of Origin co-ordinates and the chart Dimensions. If the Universal Transverse Mercator (UTM) coordinate system is used a reference Ellipsoid will also have to be selected at this point (the default is WGS84 (World Geodetic System 1984)).

16.2.3. Blank Chart

Select Use Blank to create a blank image for the chart background. A default width and height will be set.

The Point of Origin co-ordinates and the chart Dimensions will have to be set. If UTM then also select a reference Ellipsoid at this point (the default is WGS84).

16.2.4. Co-ordinate System

When creating charts the Point of Origin co-ordinates will be in the format that is currently selected in the Coordinate System panel. To change this select Cancel and navigate to the Coordinate System control (if this is not visible go to the View menu and select Coordinate System).

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16.3. Add Image Tiles

Once the chart background has been loaded sonar image tiles can be added. Tiles must be within the same geographic area of the chart background.

Either click on the Add Tile icon, or add the tile through the Tools menu and Add Tile option.

• A dialog enabling searching and adding of images is shown. The images can

be in .bmp (bitmap), .jpg (jpeg) or .tif (tiff) formats. A matching world file is

required in the same folder or the image will not load.

• The tile will be added on top of the chart if the geographic co-ordinates are within

the background area.

• Simply repeat these steps to add further tiles.

Note

Several files can be added at the same time by holding down the Ctrl key whilst selecting the images.

16.4. Manipulate Image Tiles

The position information for tiles is dependent on the settings when the tile scans were created.

If the imported position is incorrect the tiles can be repositioned on the chart at any point after they have been added to provide a more accurate mosaic. There are several repositioning functions available: moving, rotating, and resizing. As well as tools to alter the appearance of shadows in tiles: automatic cropping of unwanted shadows, manual eraser, and area erase.

For full details of the possible ways to manipulate the tiles please refer to Chapter 15,

Software Functions

16.5. Save the Project

Save Project allows the chart to be saved as a chart and a collection of tiles (and any markers) so it can be loaded for editing at a later date. The user is prompted for a file name, with the file type being XML.

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16.6. Exporting the completed mosaic as an image

Charts can either be exported whole or areas can be selected and saved. To export the entire image simply select Export as Image from the Files menu. This will then display a dialog prompting for the desired location and name of the file. This output image will have an associated world file so it can be imported into other software packages with the geo-referencing intact.

Note

If there is an area selected on the chart, clicking Export as Image will only save what is contained within the selection region. The format of the saved chart will depend on the format of the input chart (i.e., a .bmp input will generate a .bmp output).

To create an output image using the Selection Tool follow these steps:

First click on the Image Export Area button:

Using the left mouse button click and hold anywhere on the chart and then drag the cursor across the screen to create a selection area.

Click on the Files menu and go to Export as Image. Enter a filename and select the desired file type (.jpeg, .bmp or .tiff) then click Save. A world file will be created with the same filename as the image file.

Note

There will also be a .kmz file created. This is a Google Earth file format and will allow the image to be viewed in Google Earth.

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Selection area within dotted line Output image

Note

It is also possible to output just the tiles (i.e., without the background chart) by clicking on the Save Mosaic button:

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17. Supported File Formats

17.1. For Loading Tiles

In order to correctly position the images each image tile file should be accompanied by an equivalent "world file" which contains positional data. This data should come from a GPS linked into Seanet Pro. If a GPS is available Seanet Pro will automatically create a world file with the correct data when a Snapshot is taken.

The following file formats are supported:

Image Type World File

.bmp .bpw

.jpeg/.jpg .jgw

.tiff/.tif .tfw

.png .pgw

Note

The image file and world file should have the same filename (i.e., sonar.bmp and sonar.bpw).

Note

The image tiles have to be saved from the latest version of Seanet Pro; if an older version is used they will not open in the Sonar Image Tiler. If in doubt, remove the current version of Seanet Pro and either download the latest version from www.tritech.co.uk or re-install from the CD-ROM which contained the Image Tiler installation program.

17.2. Saving Images or Mosaics

Saving an image can either be the whole chart (with any visible tiles or markers), a marked out section or a mosaic of tiles either way the supported formats are:

.bmp Bitmap image

.kmz Google Earth format

.png Portable Network Graphic

Note

The Sonar Image Tiler will automatically create at matching world file for the saved image.

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17.3. Project Files

The Sonar Image Tiler uses a customised XML format for saving and loading projects. These project files will preserve any tile data or marker data so that they can be manipulated again at a later stage or transferred to another computer for editing.

Note

Due to the fact that the project files contain the data for all the tiles, if the project has many tiles it can result in the production of large XML files.

17.4. Marker Files

Two different marker file types are supported both of which are in CSV format but with different filename extensions and different complexity:

.mrk Seanet Pro full length marker files.

.csv A shortened version of the Seanet Pro format.

Note

For full details of the marker file formats please see Appendix D, Marker Files.

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18. Example: Using Sidescan Image Tiles

Several .v4log files have been created in Seanet Pro that contain SeaKing Sidescan and GPS NMEA data. Each file contains the sidescan data for one track from a lawnmower style survey. GeoTiff files (and corresponding world files) were created using the DumpLog utility and these file-sets were added/imported into the Image Tiler application as sonar image tiles.

The files used for this example were as follows:

GeoTIFF file: Outfall3.TIF World File: Outfall3.TFW

Contents of Outfall3.TFW:

0.0121457489878543 0 0

-0.121457489878543

299883.8970386512

4836012.20188229

Contents of Outfall4.TFW:

0.0121457489878543 0 0

-0.121457489878543

300067.466645638

4835950.35472915

The TIF and TFW file sets were imported into the Sonar Image Tiler using the Add Tile button. The first tile imported was used as the reference background image.

Further tiles were added and repositioned.

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With the image tiles added an area was highlighted using the Selection Tool and the area was saved to file using the Export Chart as Image button. The saved image mosaic appears as follows:

Sidescan Images provided courtesy of Cawthron, New Zealand (image shows mega ripples of sand off the coast of Foveaux Strait near Bluff)

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Part V

Service and Maintenance

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19. Maintenance

19.1. After each use of the equipment

Make sure that after using the sonar head that it is washed down with fresh water and check the unit for any signs of obvious damage.

Once the unit is clean; dry thoroughly and place in the storage container.

Note

If the unit is fitted to an ROV it is advisable to remove from its fitting and wash both with fresh water and dry both thoroughly prior to re-assembly. This will prevent the build up of corrosive salts in any crevices between the sonar and mounting bracket.

19.2. Regular maintenance

There are no user serviceable parts inside the sonar and it is not necessary to take it apart for any maintenance tasks.

A regular inspection routine should be established to ensure that the sonar head, particularly stress points such as the connectors, does not have any damage.

If the system is in regular use, or submerged routinely for extended periods, it is advisable to arrange for an annual service to be carried out by Tritech International Ltd. This service will enable the equipment to be checked thoroughly or for any worn parts to be replaced and will enable long-term trouble free operation of the sonar. For details of the servicing options available contact Tritech International Ltd.

19.3. Storage of Equipment

If storing the equipment for extended periods make sure that it is completely dry (if necessary leave to air-dry before stowing).

Pack into storage containers along with several pouches of silica gel. The original packing containers contain specific foam cut-outs for the storage of the equipment so wherever possible they should be re-used. The foam will absorb moisture so if the cases are allowed to get wet they should be dried thoroughly prior to stowing equipment in them.

Any supplied cabling is jacketed with polyurethane which is resistant to corrosion but if it is intended to store the reel for an extended period without use then it is advisable

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to un-reel the cable and dry its entire length. This will also give the opportunity to inspect the cable for any damage which has occurred during use.

19.4. Software Maintenance

The operating system required on the computer is Microsoft Windows and should have appropriate anti-virus or protection software installed.

If it becomes necessary to reload the system software it is advisable to download the latest version of Seanet Pro from www.tritech.co.uk. If no Internet connection is available the supplied CD-ROM (or USB) should be used to re-install the software.

Note

Prior to installing the software make sure that Windows and any required drivers for the computer are fully installed and working.

To ensure that the system remains secure and error free it is recommended that no extra software other than is absolutely necessary (such as anti-virus software) is installed on the computer.

If the sonar has been supplied with a Tritech SCU then the operating system can be re-initialised using the provided USB memory stick. Please refer to the SCU manual for more details (document reference: 0581-SOM-00002).

Note

A regular backup schedule for any important log files should be in place for the computer since re-initialisation may erase the hard drive contents.

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20. Troubleshooting

Continuous status Timeout 10 message

No communication with the device

(In this case the Node number of the device is 10). Check the power and communications links to the sonar head for continuity and for correct polarity, voltage and ensure that the power supply can provide sufficient current to power all devices.

If internal damage is suspected, contact Tritech International Ltd for service and repair options.

No seabed sonar targets observed

Sonar at incorrect height above seabed.

Ensure that the head is positioned sufficiently close to the seabed.

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Appendix A. ARCNET Termination

The ARCNET communication link requires a termination resistor to be installed at each end of the umbilical cable. Normally this is supplied fitted within the ARCNET cable DA-15 connector at the surface and is left for the user to fit at the sub-sea end in a convenient junction box or by use of the yellow waterblock.

Caution

Fitting the resistor inside the unit is not recommended and may invalidate the warranty.

The purpose of these terminations is to attenuate any electrical interference or "reflections" which may occur due to an impedance mis-match and the overall aim is to improve signal quality and negate any effects which might otherwise be felt by other sources of impedance such as from the cable itself.

The diagram below shows best practice to use when installing termination resistors on an ARCNET network of Tritech International Ltd sonar products.

Note

A special yellow waterblock is available from Tritech International Ltd which contains an in-line impedance of 39ohm which will enable quick and easy installation of the subsea termination resistor.

Cable length Termination Baud rate setting

Less than 100m Single 39ohm subsea resistor Normal baud rate

100-1200m 270ohm at surface and 39ohm subsea Normal baud rate

1200-2500m 270ohm at surface and 39ohm subsea Half baud rate

Note

If there is more than one sensor connected then the sub-sea resistor should be fitted at the junction box or splice of the cable.

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Appendix B. CHIRP Signal Processing

There are several advantages of Tritech International Ltd Digital Sonar Technology (DST) which allows the use of CHIRP signal processing technology in order to improve the images generated by the sonar.

In monotonic (single frequency burst) sonar, the range resolution is determined by the length of the transmitted pulse. The smaller the pulse is, the greater the resolution achievable and vice-versa. The smallest pulse length is typically 50 micro seconds and velocity of sound in water is approximately 1500 metres/second which gives a range resolution of 37.5mm. This result effectively determines the ability to resolve separate targets.

Target Seperation

Time

Transmitted Pulse

Target 1 echo

Target 2 echo

Sonar range resolution

Target seperation

Combined echo (seen by the receiver)

Using the example above, if two targets are less than 37.5mm apart then they cannot be distinguished from each other. The net effect is that the system will display a single large target, rather than multiple smaller targets.

CHIRP signal processing overcomes these limitations by sweeping the frequency within the burst over a broad range of frequencies throughout the duration of transmission pulse. This creates a signature acoustic pulse - the sonar knows what was transmitted and when. Using pattern-matching technology, it can now look for its own unique signature being echoed back from targets.

Transmitted signal

Transmitter circuit

Receiver circuit

Received decoded signal

pulse duration

In a CHIRP system, the critical factor determining range resolution is now the bandwidth of the CHIRP pulse which means the range resolution is given by:

Range resolution =

velocity of sound

2 x bandwidth

The bandwidth of a typical Tritech International Ltd CHIRP system is 50kHz

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With velocity of sound in water of 1500m/s this gives a new range resolution of 15mm.

This time, when two acoustic echoes overlap, the signature CHIRP pulses do not merge into a single return. The frequency at each point of the pulse is different, and the sonar is able to resolve the two targets independently.

Target Seperation

Time

Transmitted Pulse

Target 1 echo

Target 2 echo

Sonar range resolution

Target seperation

Combined echo

Both targets are visible.

The response from the pattern-matching algorithms in the sonar means that the length of the acoustic pulse no longer affects the amplitude of the echo on the sonar display.

Longer transmissions (and operating ranges) can be achieved without a loss in range resolution.

Additionally CHIRP offers improvements in background noise rejection, as the sonar is only looking for a swept frequency echo, and removes random noise or out-ofband noise.

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Appendix C. Networking COMv6 Devices

Overview

Some of the newer SeaKing ROV Sidescan and SK150 devices may be fitted with the COMv6 Communication PCB and have the AutoComms feature. This is meant to enable automatic connection of a single sonar device to a computer without the need to manually select communication protocols.

The sonar scans available communication settings until it finds an active one (the one which is connected to the computer). Once an active one has been found it will set its communication protocols to the correct settings to enable communication with the PC.

The AutoComms feature does not work for networked devices though and instead the following procedure should be adopted to allow communication between the sonar heads and surface PC.

The basic procedure is:

1. Set the communication protocols of the surface unit to match the sonar (i.e., if the sonar is communicating on RS232, set the surface unit to RS232)

2. Turn off AutoComms (if present)

3. Change the sonar settings to meet new requirements of the system - at which point it will "disappear" from the computer

4. Repeat for all the sonar devices to be connected

5. Change the surface unit to match the new system settings

Manually Setting Comms

Note

Unless it has been specified differently at time of purchase the factory default settings of all Tritech International Ltd sonars are RS232 serial at

115.2kBd so if AutoComms has previously been disabled these settings could be tried first.

Set Surface Unit to Match Sonar

Launch the Seanet Setup application and then select the Setup option from the Action column.

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A warning should appear to show that the settings are going to be changed, acknowledge this and then select the appropriate setting from the dialog box which presents itself. The example below shows the setting for port C of a SeaHub being changed to RS232 from RS485.

Set Sonar to New Setting

The sonar and SeaHub should both show a Status of OK and have green status colour. Once they are both in this condition select the Setup action for the sonar but this time click on the sonar which will then bring up the Digital Sonar Setup screen:

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First make sure that the Disable AutoComms option is checked and then change the Comms Mode settings in the bottom right corner. If working on an ARCNET network the baud rates should be changed by clicking on Baud Rates (in the bottom left of the above screenshot). Serial baud rates are set up using the Channel Setup screen which is accessed by returning to the main setup screen and navigating to Com Setup from the Utilities menu:

Repeat the above procedures for all sonar devices which are going to be on the network.

Set the surface control box to match the new communication protocols of the networked sonars.

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Hard Reset

To perform a "hard reset" and force the sonar back to factory settings first turn it off and then put a strong magnet over the case in the location indicated below. Power the unit up with the magnet held in place and factory settings should be restored.

Measure 55mm from casing edge in-line with puller:

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Appendix D. Marker Files

Seanet Pro includes the facility to lay a series of markers to label and track objects, points of interest and way positions. These markers can be saved to file for the purpose to re-load at a later date, to form part of a report or for use with the Sonar Image Tiler program.

There are two formats of marker file:

1. A full, comma separated file format with the filename extension .mrk

2. A shortened, comma separated format with the filename extension .csv

Full Marker File Format (.mrk extension)

This is the format that is native to Seanet Pro and includes full details of the marker configuration. The file is in an ASCII Comma Separated format and contains the following fields:

IndexValue Description

1 ID This is a unique string ID. It comprises a 2 letter header

("mk") followed by a DateTime code. Any unique string value is acceptable.

2 Group This is unused and should be set to 0.

3 X Coordinate For the .mrk file this will always be output in UTM

Easting.

4 Y Coordinate For the .mrk file this will always be output in UTM

Northing.

5 Altitude This is UTM Altitude and is currently unused.

6 UTM Zone Parallel Zone latitudinal letter (e.g. 'C' through 'X').

7 UTM Zone

Meridian

Zone longitudinal number (e.g 1 through 60).

8 UTM Ellipsoid Ellipsoid code (0 = Airy, 1 = Australian National, 2

= Bessel1841, 3 = Clarke 1866, 4 = Clarke 1880, 5 = Everest, 6 = GRS80, 7 = International 1924, 8 = Modified Airy, 9 = WGS84).

9 Point Size Applies to Circle, Square & Triangle shape types only,

otherwise set to 0.

10 Date & Time Date & Time in English(GB) Locale.

Format is "dd/mm/yyyy hh:mm:ss"

11 Shape Type 0 = Circle, 1 = Square, 2 = Triangle, 3 = Sonar Range, 4

= Preset Image (see Image Info below).

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IndexValue Description

12 Shape Colour Applies to Circle, Square and Triangle shape types only,

otherwise set to 00000000 (32 bit RGBA).

13 Font Inner Colour Applies to Comment Text (32 bit RGBA).

14 Font Outer Colour Applies to Comment Text (32 bit RGBA).

15 Marker Bitwise Bit 1 = Show Marker, Bit 2 = Show Coordinates, Bit 3 =

Show Comment Text (i.e. 00000111 = Show All).

16 Image Info Presets = Red Flag, Blue Flag, Green Flag, Buoy, Anchor,

Rock, Danger, POI, ViewPort, Sonar, Diver, Wheel, Comment or MLO Alternatively can be full path and name of an image file (e.g. 'C:\Image1.bmp').

17 Comment Comment text.

For example, the following two markers would produce a two line .mrk file as shown:

mk41149.5595988657,0,548699.614997778,6313221.96999907,-5.3544902067987E-76,V,30,9,0, 28/08/2012 13:25:51,4,00000000,00FFFFFF,00000000,7,Red Flag,Possible Wreck Site mk41149.5605201736,0,548724.213265236,6313198.87994614,-5.3544902067987E-76,V,30,9,0, 28/08/2012 13:27:48,4,00000000,00FFFFFF,00000000,7,Rock,WARNING! ROCKS

Shortened Marker File Format (.csv extension)

This file format is a more concise and usable format, particularly for loading a predefined target list into Seanet Pro. The file is in an ASCII Comma Separated format and contains the following fields:

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IndexValue Description

1 ID This is a unique string ID. It comprises a 2 letter header

("mk") followed by a DateTime code. Any unique string value is acceptable.

3 X Coordinate For the .csv file, will be in coordinate system used in

Seanet (either Longitude or UTM Easting).

4 Y Coordinate For the .csv file, will be in coordinate system used in

Seanet (either Latitude or UTM Northing).

17 Comment Comment text.

11 Shape Type 0 = Circle, 1 = Square, 2 = Triangle, 3 = Sonar Range, 4

= Preset Image (see Image Info below).

16 Image Info Presets = Red Flag, Blue Flag, Green Flag, Buoy, Anchor,

Rock, Danger, POI, ViewPort, Sonar, Diver, Wheel, Comment or MLO Alternatively can be full path and name of an image file (e.g. 'C:\Image1.bmp').

10 Date & Time Date & Time in English(GB) Locale.

Format is "dd/mm/yyyy hh:mm:ss"

For example, the following two markers would produce a two line .csv file as shown:

mk41149.5595988657,-2.1991799999203,56.9600300036883,Possible Wreck Site,4,Red Flag, 28/08/2012 13:25:51 mk41149.5605201736,-2.19877999992026,56.9598200036882,WARNING! ROCKS,4,Rock, 28/08/2012 13:27:48

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Glossary

.bmp The standard filename extension for bitmap images.

.kml The standard filename extension for a Keyhole Markup

Language file which contains georeferencing data. This file will either be incorporated within a .kmz file or requires an accompanying image file (with the same file name) to be valid. Used by Google Earth.

.kmz The standard filename extension for a compressed file containing

the Keyhole Markup Language file (.kml) and image file. For storing georeferencing data and images in a single file. Used by Google Earth.

.mrk The standard filename extension for marker files exported from

Seanet Pro, saved as a text file in tabular format with table cells separated by commas.

.png The standard filename extension for Portable Network Graphics

- a bitmapped image format employing lossless compression.

.tiff or .tif The standard filename extension for Tagged Image File Format.

.v4log The standard file format used by Seanet Pro log files.

ARCNET Attached Resource Computer NETwork - a network protocol

similar to Ethernet but with the advantage of working over much longer ranges.

ASCII American Standard Code for Information Interchange - a

character encoding scheme originally based on the English alphabet.

AutoComms

Hardware developed by Tritech International Ltd for use in sonar heads which enables the sonar to automatically switch to the correct communication protocol to match that of the surface controller.

CD-ROM Compact Disc - Read Only Memory

CPU Central Processing Unit, the processor of a computer.

CSV Comma Separated Value - a text file in tabular format with table

cells separated by commas, usually given the filename extension .csv but this can vary depending on the application.

DC Direct Current

DST Digital Sonar Technology

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GeoTiff A public domain standard file format which allows

georeferencing information to be embedded into a TIFF (Tagged Image File Format) image, uses the filename extension .tif or .tiff.

Google Earth A virtual globe, map and geographical information program,

originally called EarthViewer 3D prior to being acquired by Google Inc. in 2004.

GPS Global Positioning System.

JPEG or JPG Joint Photographics Expert Group - a compression method and

file format for image files, files can be stored with either .jpeg or .jpg file extensions

Kevlar Poly-paraphenylene terephthalamide high strength, light weight,

material branded and sold as Kevlar by DuPont.

NMEA National Marine Electronics Association - a USA based

standards association responsible for overseeing electrical and data communications standards between marine devices (due to become the IMEA or International Marine Electronics Association in 2012).

PC Personal Computer

PCB Printed Circuit Board

PSU Power Supply Unit

RAT Remote Access Terminal - the detachable front part of the Tritech

Surface Control Unit (SCU) computer. Provides an alternative to using a keyboard and mouse.

ROV Remotely Operated Vehicle

RS232 Traditional name for a series of standards for serial binary data

control signals.

RS485 A standard for defining the electrical characteristics of drivers

and receivers for use in a balanced digital multipoint system (also known as EIA-485).

RX Receive (data)

SCU Surface Control Unit - a specially manufactured computer which

is rack mountable and capable of processing the data from the sonar equipment running either Windows XP Embedded or Windows 7 and Seanet Pro or Gemini software.

SeaKing

A specific sonar produced by Tritech International Ltd but also refers to the family of sonar equipment manufactured by Tritech

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International Ltd comprising of the SeaKing, SeaKing DST scanning and profiling sonars and the Hammerhead survey sonar.

Seanet Pro

The software supplied by Tritech International Ltd which is capable of running all the sonar devices.

Sidescan A sonar that is typically towed behind a boat or mounted to the

side of an ROV which takes a series of narrow sonar images that are joined together to form strips. Typically used for survey work.

Tritech waterblock

The 4000m depth rated connector developed by Tritech International Ltd for their subsea equipment.

TX Transmit (data)

USB Universal Serial Bus.

USBL Ultra Short Base Line (positioning system)

UTC Coordinated Universal Time (time data closely related to

Greenwich Mean Time (GMT)).

UTM Universal Transverse Mercator coordinate system - a 2-

dimensional Cartesian coordinate system to give locations on the surface of the Earth.

WGS84 World Geodetic System (1984 revision) - a standard for use in

cartography, geodesy and navigation and used as the reference coordinate system by GPS devices.

world file A file used by the Tritech Sonar Image Tiler program which

is designed to accompany an image file and contains georeferencing data. The file format will have different extensions depending on the format of the image file:

Image type World file

extension

.bmp .bpw

.jpg or .jpeg .jgw

.tif or .tiff .tfw

.png .pgw

XML Extensible Markup Language. A markup language and file

format that is designed to be both human and machine readable.

Tritech SeaKing Sidecan, SeaKing SK150 Sidescan, ROV Sidescan, Towfish, SeaKing Towfish Sidecan Operator's Manual

Specifications and Main Features

Frequently Asked Questions

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