Furuno CSH-53 User Manual

COLOR SCANNING SONAR

MODEL

CSH-53

9-52 Ashihara-cho,9-52 Ashihara-cho,

*00080807300**00080807300*

*OME13070D00**OME13070D00*

Nishinomiya, JapanNishinomiya, Japan

Telephone :Telephone : 0798-65-21110798-65-2111 Telefax :Telefax : 0798-65-42000798-65-4200

Your Local Agent/DealerYour Local Agent/Dealer

ll rights reserved.

PUB.No.PUB.No. OME-13070OME-13070

(( DAMIDAMI ))

CSH-53CSH-53

Printed in JapanPrinted in Japan

FIRST EDITION :FIRST EDITION : JUL.JUL. 19971997

D :D : APR.APR. 04,200204,2002

* 0 0 0 8 0 8 0 7 3 0 0 ** 0 0 0 8 0 8 0 7 3 0 0 *

*OME13070D00**OME13070D00*

* O M E 1 3 0 7 0 D 0 0 ** O M E 1 3 0 7 0 D 0 0 *

SAFETY INSTRUCTIONS

WARNING

Do not open the equipment.

Hazardous voltage which can cause electrical shock, burn or serious injury exists inside the equipment. Only qualified personnel should work inside the equipment.

Do not disassemble or modify the equipment.

Fire, electrical shock or serious injury can result.

Turn off the power immediately if water leaks into the equipment or the equipment is emitting smoke or fire.

Continued use of the equipment can cause fire or electrical shock.

CAUTION

Use the proper fuse.

Use of a wrong fuse can result in fire or permanent equipment damage.

Do not use the equipment for other than its intended purpose.

Personal injury can result if the equipment is used as a chair or stepping stool, for example.

Do not place objects on the top of the equipment.

The equipment can overheat or personal injury can result if the object falls.

Do not exceed speed noted in the specifications when operating the equipment or lowering or raising the transducer.

Do not place liquid-filled containers on the top of the equipment.

Fire or electrical shock can result if a liquid spills into the equipment.

Do not operate the equipment with wet hands.

Electrical shock can result.

Keep heater away from equipment.

Heat can alter equipment shape and melt the power cord, which can cause fire or electrical shock.

The transducer may become damaged.

The zinc block attached near the transducer must be replaced yearly.

The junction between the transducer and main shaft may corrode, which can result in loss of the transducer or water leakage inside the ship.

POSSIBILITY OF INJURY

1. If breaker (hull unit) trips do the following:

1) Turn off power swich on hull unit.

2) Wait 60 sec after breaker has tripped.

3) Press breaker.

2. Turn off hull unit before using hand crank.

iiiiiiiiiiiii

T ABLE OF CONTENTS

FOREWORD

A Word to CSH-53 Owners ......................................................................................................v

Features.....................................................................................................................................v

System Configuration ..............................................................................................................vi

CONTROL DESCRIPTION

Control Layout on Display Unit and Remote Control Box ...................................................1-1

Main Panel.............................................................................................................................1-2

Sub Panel 1 ............................................................................................................................1-4

Sub Panel 2 (data setting window) ........................................................................................1-5

Remote Control Box..............................................................................................................1-8

OPERA TIONAL OVER VIEW

Turning the Power On/Off .....................................................................................................2-1

Adjusting Screen Brilliance, Control Panel Backlighting .....................................................2-1

Lowering the Transducer .......................................................................................................2-1

Selecting a Display Mode......................................................................................................2-2

Selecting a Display Range.....................................................................................................2-3

Setting the Tilt Angle.............................................................................................................2-3

Adjusting the Gain.................................................................................................................2-7

Measuring Range and Bearing to a Target.............................................................................2-7

FINE TUNING THE PICTURE

Eliminating Unwanted Feeble Echoes...................................................................................3-1

Suppressing Seabed Tail ........................................................................................................3-3

Suppressing Seabed and Sea Surface Reflections in Shallow Waters ...................................3-4

Rejecting Sonar Interference and Noise ................................................................................3-4

MARKS AND DATA

Marks, Data and Display Mode.............................................................................................4-1

Permanently Displayed Marks and Data ...............................................................................4-3

Erasable Marks and Data .......................................................................................................4-4

MENU OVERVIEW

USER Menu Operation..........................................................................................................5-1

USER Menu Description .......................................................................................................5-3

SYSTEM Menu Description .................................................................................................5-5

DATA SET Menu Description...............................................................................................5-8

INIT SET/TEST Menu Description.....................................................................................5-11

FUNCTION KEYS

Programming the Function Keys ...........................................................................................6-1

Replaying a Function Key .....................................................................................................6-1

Function Key Fine Tuning.....................................................................................................6-2

Saving Function Key Settings to a Memory Card .................................................................6-3

Replaying Function Key Settings from a Memory Card .......................................................6-3

ADVANCED LEVEL OPERATION

Finding Fish School Center ...................................................................................................7-1

Tracking a Fish School ..........................................................................................................7-2

Detecting Fish Schools Aurally .............................................................................................7-7

The Fish Alarm......................................................................................................................7-8

Relocating Fish School for Easy Observation .......................................................................7-9

Comparing of Fish School Concentration ...........................................................................7-10

Measuring Fish School Speed .............................................................................................7-11

The Event Mark ...................................................................................................................7-12

True Motion Display............................................................................................................7-14

Plotting Net Location Mark .................................................................................................7-15

Observing Net Behavior ......................................................................................................7-16

Reducing Sea Surface Reflections.......................................................................................7-17

Boosting Tx Power ..............................................................................................................7-17

PORT/STARBOARD, HORIZONTAL SLICE DISPLAYS

Port/Starboard Display ..........................................................................................................8-1

Horizontal Slice Display........................................................................................................8-2

SAVING, REPLAYING PICTURE

Initializing Memory Cards.....................................................................................................9-1

Saving the Picture ..................................................................................................................9-2

Transferring Echo Data from Internal Memory to Memory Card .........................................9-2

Saving Net Shooting Data .....................................................................................................9-3

Replaying Saved Data ...........................................................................................................9-4

Deleting Memory Card Contents...........................................................................................9-4

TURNING MARKS, DATA ON/OFF ..................................................................10-1

INTERPRETING THE DISPLAY

Seabed Echoes .....................................................................................................................11-1

Fish Schools.........................................................................................................................11-2

Sea Surface Reflections .......................................................................................................11-3

Wake ....................................................................................................................................11-3

False Echo by Sidelobe........................................................................................................11-4

Noise and Interference.........................................................................................................11-4

iii

WARNINGS

Overvoltage Warning ...........................................................................................................12-1

Unretracted Transducer W arning.........................................................................................12-1

SELF TESTS

Opening the Self Test Menu ................................................................................................13-1

Self Test Description............................................................................................................13-2

Interface Unit CS-120A Self Test........................................................................................13-5

INPUT DATA SELECTION

Selection of Data on Interface Unit CS-120A .....................................................................14-1

Setting Distances Between Net Sonde T ransmitters............................................................14-2

MAINTENANCE

Display Unit Maintenance ...................................................................................................15-1

Hull Unit Maintenance ........................................................................................................15-2

MENU TREE..................................................................................................................A-1

SPECIFICATIONS..................................................................................................... SP-1

INDEX.............................................................................................................................. IN-1

FOREWORD

A Word to CSH-53 Owners

Congratulations on your choice of the FURUNO CSH-53 Color Scanning Sonar. We are confident you will see why the FURUNO name has become synonymous with quality and reliability .

For over 40 years FURUNO Electric Company has enjoyed an enviable reputation for quality marine electronics equipment. This dedication to excellence is furthered by our extensive global network of agents and dealers.

This equipment is designed and constructed to meet the rigorous demands of the marine environment. However, no machine can perform its intended function unless operated and maintained properly . Please carefully read and follow the recommended procedures for operation and maintenance.

We would appreciate hearing from you, the end-user, about whether we are achieving our purposes.

Thank you for considering and purchasing FURUNO equipment.

Features

The FURUNO CSH-53 Color Scanning Sonar is a full-circle, multibeam electronic scanning sonar which detects and instantaneously displays fish schools and underwater conditions in 16 colors on a 15" non-glare, high resolution CRT screen.

The main features of the CSH-53 are

• V ivid 16-color display provides intuitive recognition of seabed and concentration, distribution and volume of fish schools.

• Markers and indications keep the operator abreast of fishing conditions.

• Remote control box provides for armchair control of major functions.

• New gain, range or tilt setting appears in large characters whenever corresponding control is adjusted.

• Function keys automatically setup the equipment to perform specific task.

• High power MOS FET transmitter ensures reliable operation under any condition.

System Configuration

STANDARD OPTION

REMOTE CONTROL BOX

CSH-135

SHIP’S MAINS 100 VAC, 1∅, 50/60 Hz

TRANSMITTER UNIT

CSH-551

DISPLAY UNIT

CSH-530

HULL UNIT

(w/RECEIVER UNIT) CSH-552

REMOTE DISPLAY

CSH-106

110/115/220/230 VAC, 1∅, 50/60 Hz

INTERFACE UNIT

CS-120A

SUB DISPLAY

CSH-536

SHIP’S MAINS 100 VAC, 1∅, 50/60 Hz

STEP-DOWN

TRANSFORMER

PT-400

SPEED LOG AD CONVERTER NAVIGATOR CURRENT INDICATOR COLOR VIDEO SOUNDER

CSH-5508 (800 mm stroke) CSH-5512 (1200 mm stroke)

VI-1100A

FNZ JOINT BOX

CS-170

INTERFACE UNIT

ECHO SOUNDER, COLOR VIDEO SOUNDER

NET SONDE

CONTROL DESCRIPTION

Control Layout on Display Unit and Remote Control Box

POWER TRANSDUCER

OFF ON

SUB PANEL 1

Selects which display unit to control in multiple display unit

installation. Raises/lowers the transducer. : Raises transducer. : Mid protrusion : Full protrusion

Press to enter mark shown on key or shift screen center.

Selects display range.

Adjusts receiver sensivity.

Not used.

PUSH-OPEN

SUB PANEL 2

EVENT

ESTIMATE

FISH

+ –

RANGE

DISP SELECT

TGT LOCK

NET COURSE

OFFCENT

FUNCTION

234

–

GAIN

AUTO

TRAIN

TARGET

LOCK

ESTI-

MATE2

OFFCENT

SCAN DEPTH

TILT

SCAN DEPTH

DIM CONT BRILL AUDIO

DATA

MEMO

TILT

F1 F2 F3

NORM E/S HIST RECALL MEMO

RANGE GAIN

NARROW BOOST

SHOOT R/B

NET

COURSE

EVENT1 EVENT2

ESTI-

MATE1

FISH

SHOOT

NARROW RECALL

AUTO

BOOST

AUTO

TILT

WIDTH

MAIN PANEL

Each press displays water temperature or depth at screen center for about five seconds.

Turns on transmitter.

Shifts trackball mark.

Replays user preset settings. Lit lamp shows current selection.

Displays net shooting mark. Saves picture to memory card. Sharpens width of Tx beam.

Replays a stored picture. Automatically tillts sounding

beam in 2° steps within tilt angle selected by WIDTH key.

Varies the tilt angle of the sounding beam between -5° and 60°.

Changes weight in vertical direction at Tx.

Figure 1-1 Display unit and remote control box

1-1

Main Panel

POWER TRANSDUCER

OFF ON

F1 F2 F3

NORM E/S HIST RECALL MEMO

RANGE GAIN

NARROW BOOST

SHOOT R/B

NET

COURSE

EVENT1 EVENT2

ESTI-

MATE1

FISH

TARGET

LOCK

ESTI-

MATE2

OFF-

CENT

DIM CONT BRILL AUDIO

TILT

SCAN DEPTH

AUTO

TILT

WIDTH

1-2

Figure 1-2 Main panel Main panel control description

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Control Function

NORM, E/S, HIST (Mode keys)

RECALL, MEMO RECALL: Replays saved picture.

RANGE Selects a picture display range. Range selected appears on the display. GAIN Adjusts receiver sensitivity. NARROW Sharpens width of Tx beam when turned on (light above key is on).

BOOST Changes weight of vertical direction during transmission when turned

SHOOT Press when net is cast. The net shooting mark, *net sonde marks and

R/B Provides range and bearing data from own ship to a target. Select

Select display mode: NORM, normal sonar picture; E/S, Echosounder combination; HIST, Historical display. Lamp above a key lights to show current selection.

MEMO: Saves picture to memory card or internal memory.

The off position provides normal Tx beamwidth.

on.

*current mark appears at the own ship mark. The net shooting mark, net sonde marks and current mark moves on the *ship's track as the ship moves. The lamp above the switch lights and time *distance run appear on the display unitl the net shooting mark is turned off.

(* Requires external sensor.)

target with trackball and then press the R/B key. A line connects between own ship mark and trackball mark to measure bearing.

TILT Changes the tilt angle of the sounding beam between -5°and 60°. AUTO TILT Automatically tilts the sounding beam up and down in 2° steps within

the tilt angle selected by the WIDTH key. The lamp above the key

lights when automatic tilt is on. WIDTH Sets tilt width in automatic tilt. NET COURSE Marks location of net. TARGET LOCK Tracks a fish school. EVENT 1, 2 Inscribes event mark on the display, to find horizontal, range, depth

and bearing of a target. ESTIMATE 1, 2 Compares volume of two fish schools. FISH Measures fish school speed. OFF-CENT Relocates selected target. DIM Adjusts the backlighting of the control panels and the brightness of

the lamps above keys CONT Adjusts screen contrast. BRILL Adjusts screen brilliance. AUDIO Adjusts volume of built-in loudspeaker, which monitors a target

appearing along the bearing marker. TRACKBALL Follows on-screen movement of trackball mark, to enter marks and

off-center the screen.

1-3

Sub Panel 1

POWER

OFF

CARD

REPLAY

TRANSDUCER

COLOR

NET

REPLAY

RECALL

Figure 1-3 Sub panel 1 Sub panel 1 control description

END

HELP

F5F3F2F1

MEMOHISTE/SNORM

Control Function

MENU Opens/closes the menu. END • When the menu is displayed it terminates menu operation and

returns control to the sonar picture.

• When in a sub menu it returns to previous sub menu.

HELP Provides operating information for current menu.

cd[ \

Select items on menus.

CARD REPLAY Replays card-stored control and menu settings. COLOR Changes display color among four choices. NET REPLAY Replays internally stored net shooting data. To replay, press key to

light lamp above it, select item to replay, and press the key again.

TX Press to transmit, when transducer is lowered. Lamp lights during

transmission.

1-4

Sub Panel 2 (data setting window)

ITEM

(TVG•TX selected)

This example shows settings of TVG and TX.

SONR•BEAM

OPER P-SET

(TOGGLE)

TVG•TX

SIGNAL

DELETE MK

AUTO

ALM•AUDIO

CURRENT SETTINGS for item selected (TVG•TX)

NEAR7MEDIUM

+ + + + + + – – – – – –

Item selection keys Select item.

TVG TX

FAR

Setting change keys Change control setting.

CYCLE

OUTPUT

Main

Item

TVG•TX

OPER P-SET key Opens/closes data setting window.

Figure 1-4 Sub panel 2 Sub panel 2 control description

Item

Main Sub

NEAR 0–9

TVG

TRANSMIT

MEDIUM 0–9

FAR 0–9

CYCLE 0–9

PL 0–9

Setting

Range

Description

Adjusts receiver gain within 100 m.

Adjusts receiver gain between 100 m and 400 m.

Adjusts receiver gain beyond 400 m.

Sets Tx cycle. 9 is normal setting (fastest). "0" synchronizes with external KP.

Sets Tx pulselength. 9 is normal setting.

Normal

Setting

(Continued on next page)

OUTPUT 0–9

Sets Tx output power. 9 is maximum power.

1-5

Main Item

Item

Main Sub

SIGNAL PROCESS

Setting

Range

NL 0–10 Rejects unwanted echoes. 3

Automatically reduces receiver

AGC 0–10

2AGC* 0–4

gain against strong echoes such as seabed. Adjust so fish echo is displayed near seabed.

Suppresses seabed echoes. If AGC alone cannot suppress seabed echoes, use 2AGC.

Description

Normal

Setting

SIGNAL

SIGNAL PROCESS

ES1 (Net Recorder)

Selects echo level versus presen-

CURVE 1–4

IR 0–3

AFGLOW 0–4

RANGE (DN RNG)16Pos.

GAIN 0–10 Adjusts receive sensitivity. 5

SHIFT (UP RNG)0–1000 m

NL 0–10

COLOR 0–9

ON,

OFF

tation color curve. The higher the setting, the easier it is to see weak echoes on the screen.

Rejects random noise and interference by other echo sounders or sonars.

Adjusts echo afterglow, which is useful for watching echo movement. The higher the setting the longer the afterglow remains.

Sets depth range of echo sounder picture. Sets range of net recorder downward sounding.

Sets display start depth of echo sounder picture. Sets range of net recorder upward sounding.

Rejects blue dots (caused by dirty water) on entire screen.

Eliminates echoes displayed in colors specified.

Eliminates interference by other sonars or echo sounders.

160 m

0 m

OFF

Each pressing erases oldest mark among event mark 1, event mark 2, fish mark, own ship mark.

Each pressing deletes 1/5 of overall length.

DELETE MK

DELETE MARK

+ or -

key to

erase.

TRACK

*2AGC and HOR functions cannot be used together. If one is used the other is automatically set to “0”.

(Continued on next page)

1-6

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1-7

Remote Control Box

Selects which display unit to control in multiple display unit installation.

Raises/lowers the transducer.

c: Raises transducer.

d: Mid protrusion

d: Full protrusion

Press to enter mark shown on key or shift screen center.

Selects display range.

Adjusts receiver sensivity.

Not used.

EVENT

ESTIMATE

FISH

+ –

RANGE

DISP SELECT

FUNCTION

–

AUTO

BOOST

SHOOT

NARROW RECALL

TGT LOCK

NET COURSE

OFFCENT

234

GAIN

AUTO

TRAIN

DATA

MEMO

TILT

SCAN DEPTH

Each press displays water temperature or depth at screen center for about five seconds.

Turns on transmitter.

Shifts trackball mark.

Replays user preset settings. Lit lamp shows current selection.

Displays net shooting mark. Saves picture to memory card. Sharpens width of Tx beam.

Replays a stored picture.

Automatically tillts sounding beam in 2° steps within tilt angle selected by WIDTH key.

Varies the tilt angle of the sounding beam between -5° and 60°.

Figure 1-5 Remote control box

Changes weight in vertical direction at Tx.

1-8

OPERA TIONAL OVERVIEW

T urning the Power On/Off

Turning the power on

Press the ON switch on the main panel. The lamp above the key should light. If it doesn’t press the TX switch on sub panel 1.

Turning the power off

Retract the transducer with the c switch and then press the OFF key on the main panel.

Note: The transducer is automatically retracted into the tank even if the OFF switch is pressed before retracting the transducer. However, make it a habit to retract the transducer before turning off the power .

Adjusting Screen Brilliance, Control Panel Backlighting

The BRILL control adjusts screen brilliance, and the DIM control adjusts control panel backlighting. These controls are on the lower part of the main panel.

Lowering the T ransducer

Press d or d switch. The lamp above the key blinks during lowering of the transducer and lights when the transducer is completely lowered. In normal use fully lower the transducer. The transducer extends 1200 mm below the ship’s hull, providing stable and cavitation-free soundings. If the transducer may become entangled in the net, after shooting the net, for example, partially raise the transducer with the the transducer by 400 mm (transducer extends 800 mm from ship’ s hull).

d switch. This raises

Do not exceed speed noted in the specifications when operating the equipment or lowering or raising the transducer.

The transducer may become damaged.

Do not press the c switch during lowering of the transducer, and do not press the of the transducer.

CAUTION

d or d switch during raising

The equipment may become damaged.

2-1

Selecting a Display Mode

The CSH-53 provides three display modes: normal sonar picture, echo sounder combination, and history display combination. Those modes may be selected with the NORM, E/S and HIST keys.

Table 2-1 Display mode description

Mode Description

The sonar picture appears over the entire screen. This mode is useful for detecting and tracking fish schools. The default display area is 1.3 times the range, but it can be changed to

1.6 times the range on "EXT KP/TM DSP" in the SYSTEM menu. Navigation information can be displayed in the text window at the screen bottom by turning on

NORMAL

"DATA DISPLAY" in the user menu.

Text window

E/S

Normal scanning picture appears on the upper 5/8 of the screen and the signal fed from the echo sounder on the lower 3/8. This mode is suitable for judging fish school concentration. When two echo sounders are connected, each pressing of the E/S key alternately selects echo sounder 1 or echo sounder 2. Note that a net recorder can be connected as echo sounder 2; select it on the "ES" sub menu in the INIT SET/TEST menu.

Normal scanning sonar picture appears on the upper 5/8 of the screen and the history display on the lower 3/8. Three types of history displays are available: Audio, Port/Starboard and Horizontal Slice. You can select which one to display on the USER menu.

2-2

HISTORY

Selecting a Display Range

Operate the RANGE control to select a display range. The range selected appears at the top center of the screen.

Setting the Tilt Angle

The tilt angle shows the direction to which the sound wave is emitted. When the sound wave is emitted horizontally, the tilt angle is said to be zero degrees and when emitted vertically, 90 degrees.

To set a tilt angle, operate the TILT lever. W atch the tilt angle indication at the top right

R400 T 15

Tilt angle

corner on the screen. The tilt angle can be set in one-degree steps from -5° (upward) to 60° (downward).

Finding a proper tilt angle is important when searching for fish. Below are tips for selecting tilt angle.

Seabed echo and tilt angle

Case 1: Tilt angle 30 to 40 degrees This tilt angle will display the entire seabed since it is captured

by the full width of the beam. Case 2: Tilt angle 10 to 20 degrees This tilt angle will only display half the seabed since it is only

captured by the lower half of the beam. Case 3: Tilt angle 0 to 10 degrees This tilt angle may or may not capture the seabed since the re-

turning echo is weak.

2-3

How to discriminate fish echoes from the seabed

The figure below illustrates how two fish schools a and b are displayed on the screen using three different tilt angles.

Case 1: Tilt angle 30 to 40 degrees. Fish school is obscured by the seabed.

Case 2: Tilt angle 10 to 20 degrees. Fish school is located above the seabed (midwater).

Case 3: Tilt angle 0 to 10 degrees. Fish school is located close to the seabed.

Case 1

Seabed

Case 2

Fish school aFish school a

Seabed

Case 1 Case 2

Figure 2-1 Fish echo and tilt angle

Case 3

Seabed

Fish school a

Fish school

Case 3

2-4

Points to consider

• Normally , a vertically distributed fish school is a better sonar target than the seabed, because it reflects the transmitted pulse back toward the transducer .

• In case 3, both fish schools a and b are presented. Generally speaking, however, midwater fish schools tend to be lar ger than bottom fish schools and they are often displayed near the seabed on the display.

• It is difficult to detect bottom fish when they are not distributed vertically .

Tilt angle for surface fish

Sound emitted from the sonar transducer forms a circle-shaped beam with a width of approximately 16 degrees in the vertical direction (vertical beam width). The tilt angle is indicated by the angle between the center line of the beam and the horizontal plane. Then, if the tilt angle is set to 0 degrees, the center line is parallel with the sea surface and one half of the emitted sound goes upward, toward the sea surface.

This causes one half of the emitted sound to be reflected toward the transducer and displayed on the screen as sea surface reflections. When the sea is calm, since the sound is reflected just like a light hitting a mirror at a narrow incident angle, it propagates away and the sea surface reflections become negligible.

However if the sea is not calm enough, they will become dominant and interfere with observation of wanted echoes. To minimize these sea surface reflections and to search surface fish schools effectively, the tilt angle is usually set between 5 and 6 degrees so the upper portion of the beam becomes almost parallel with the sea surface. When the sea is rough, it is often set to a little larger angle.

Surface

Tilt angle 0°

Tilt angle 5-6°

15°

Surface

15°

Figure 2-2 Tilt angle and sea surface reflections

2-5

Suitable tilt angle

The figure below illustrates the relationship among tilt angle, depth and detection range. Refer to it to find out the suitable tilt angle for a given depth/detection range.

Tilt angle and beam coverage

20(40) 40(80)

60(120)

80(160)

100(200)

Depth (m)

200(400)

Vertical width of sonar beam

100 m100 m

15°

100

(200)

26 m

200

(400)

200 m

52 m

300

(600)

300 m

78 m

Range (m)

400

(800)

0°

5°

10°

15°

Figure 2-3 Tilt angle and beam coverage

2-6

Adjusting the Gain

The GAIN control adjusts receiver sensitivity (gain). Adjust it so fish echoes are clearly displayed with minimal noise on the screen. Too high a setting not only displays excess noise and makes it difficult to discriminate wanted echoes but also causes seabed echoes to be painted in strong colors, resulting in echoes being masked by seabed reflections. Normally, set the control somewhere between positions “3” and “7”.

Gain low

Gain proper

Figure 2-4 Gain settings and r esulting picture

Measuring Range and Bearing to a T arget

Operate the trackball to place the trackball mark on the target you want to measure the range and bearing. The range and bearing appear at the upper left corner on the screen.

Figure 2-5 Location of range and bearing indications

Gain high

Note: The bearing is shown in either 360° or 180° indication relative to ship’s heading. In the latter case, bearing (“B”) is indicated as follows:

B P ------- on the port side B S ------- on the starboard side

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FINE TUNING THE PICTURE

Eliminating Unwanted Feeble Echoes

Echoes from targets such as seabed and fish return to the transducer in order of distance to them, and when we compare their intensities at the transducer face, those from nearer targets are generally stronger when their reflecting properties are nearly equal. The sonar operator will be quite inconvenienced if these echoes are directly displayed on the screen, since he can not judge the actual size of the target from the size of echoes displayed on the screen. T o overcome this inconvenience, the TVG function is incorporated. It compensates for propagation loss of sound in water; amplification of echoes on short range is suppressed and gradually increased as range increases so that similar targets are displayed in the similar intensities irrespective of the ranges to them.

The CSH-53 has three TVG functions, NEAR, MEDIUM and F AR, and they mainly compensate for propagation loss on short, middle and long ranges respectively , centered at the ranges shown below . The higher the TVG setting the greater the amplification of echoes.

Near

About 100 m

Med

About 400 m

Far

Figure 3-1 Principle of TVG

The TVG is also used to suppress unwanted echoes and noise which appear in a certain range area on the screen such as sea surface reflections and cruising noise. To set TVG properly, do the following:

How to adjust TVG

1. Open sub panel 2.

2. Select TVG•TX.

3. Set TVG NEAR, MEDIUM and FAR to 5.

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4. When sea surface reflections or plankton layers disturb the

picture, decrease appropriate TVG option by one or two steps by pressing – (minus) key.

5. Locate fish school on a long range setting (about 800 meters)

which is approaching own ship.

6. Adjust the tilt to keep the fish school in the center of the

sonar beam, namely, fish school is displayed in strongest colors possible. Confirm that the fish echo is displayed in the same color as it approaches. If the color suddenly changes to weaker colors as the fish enters MEDIUM and NEAR areas, the TVG is improperly set. Adjust the TVG. If this again produces sea surface reflections and noise try to remove them with AGC and NL controls.

Note: If the above procedure does not produce satisfactory results, the TVG curve can be changed on the SYSTEM menu. The 15 log setting is useful for searching fish schools near shorelines or shallow waters. The 30 log setting raises the gain on a long range and is suitable for tuna and bonito, which are usually searched with high gain setting.

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Suppressing Seabed Tail

AGC (data setting window: SIGNAL, SIGNAL PROCESS)

The AGC functions to automatically reduce the receiver gain only against strong echoes such as the seabed or a large fish school. Since weak echoes remain unaffected, a small fish school becomes easier to detect. Adjust it so that the AGC works only on seabed reflections. Do not set it too high; weak echoes may be missed.

Pulselength (data setting window: TVG • TX, PL)

The pulselength control determines the length of the transmission pulse emitted into the water. While a longer pulse is advantageous for long range sounding, it has the disadvantage of being poor in discrimination of targets, that is, ability to separate several closely located targets. When searching bottom fish, therefore, it is useful to shorten the pulselength in order to separate fish echoes from seabed reflections. Decrease the PULSELENGTH setting to shorten the pulselength. For search of surface and midwater fish in which seabed reflections are not so strong, use the longest pulselength “10”.

2AGC (data setting window: SIGNAL, SIGNAL PROCESS)

While it is ideal to suppress seabed echoes with the AGC control alone there are some fishing grounds where this is not possible. (The high power sonar has the advantage of long-range detection but this can also be a disadvantage, since weaker echoes may be hidden in strong, unwanted echoes such as the seabed.)

If you cannot suppress seabed echoes or sea surface reflections by the AGC control alone, use the 2AGC control. Normally a setting of 2 or 3 is suitable. For especially strong echoes, use a setting of 4 or 5.

AR, -4 to 1: Adjusts horizontal beamwidth

2AGC function is fixed at “3”. 0: 2AGC function is off. 1 to 5: Larger the number, the greater the effect of

2AGC.

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Suppressing Seabed and Sea Surface Reflections in Shallow Waters

Data setting window: TVG•TX, OUTPUT

In shallow fishing grounds with hard or rocky bottom, seabed reflections often interfere with wanted fish echoes and they can not be eliminated sufficiently with the aforementioned TVG and AGC controls, especially when the TILT is set to a larger angle in order to track fish schools approaching within 400 m. In such cases try to reduce the output power by adjusting the OUTPUT control instead of turning down the gain. The picture becomes clearer when output power is reduced rather than when the GAIN is decreased as illustrated below.

WRONG METHOD

CORRECT METHOD

Fish echo

TVG and AGC adjusted with OUTPUT kept high

OUTPUT decreased with GAIN kept constant

Figure 3-2 How to suppress seabed and sea surface reflections in shallow waters

Fish echo weakened

Fish echo

Rejecting Sonar Interference and Noise

While observing the sonar picture, you may encounter occasional or intermittent noise and interference. These are mostly caused by on-board electronic equipment, engine or propeller noise, or electrical noise from other sonars being operated nearby.

Identifying noise source

T o eliminate noise effectively , you should first identify the noise source as follows:

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1. Turn off the TX switch and operate all on-board equipment

one by one while observing the picture.

2. Run the boat at various speeds to check if the noise is speed

dependent.

If neither of the above two steps has effect on the picture, adjust one of the following:

Interference rejector (data setting window: SIGNAL, SIGNAL PROCESS)

This control is similar to the interference rejector on echo sounders and radars. It is effective for rejecting random noise and sea surface reflections in rough sea conditions. Set it so that noise is just eliminated. Do not use an unnecessarily high setting since it may also reject small wanted echoes.

Changing Tx cycle (data setting window: TVG•TX, CYCLE)

When other sonars operate nearby at the same transmission interval as that of own ship’s sonar , an interference ring caused by other sonars is displayed. To erase the interference ring from the screen, reduce the CYCLE on the data setting window.

Interference

Tx cycle high Tx cycle lowered

Figure 3-3 How CYCLE works

Note: When the sonar is used in shallow water with the range set between 60 m and 200 m and Tx cycle at “9”, seabed reflections caused by the 2nd-to-the-last transmission may appear on near ranges. Reduce the Tx cycle setting to “2” or “3” to suppress them.

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Setting F-shift (data setting window: SONR•BEAM, SONAR)

If interference cannot be suppressed by the interference rejector (IR) or Tx cycle, change the setting of F-SHFT from 1 to 2.

Noise limiter (data setting window: SIGNAL, SIGNAL PROCESS)

W eak, unwanted reflections, colored light-blue or green, appear when the water is dirty, plankton layers exists, or due to ship’s noise. The noise limiter (NL) can reduce the effects of these unwanted reflections–raising the setting causes them to become bluish to background color. Normally a setting of 3 or 4 is suf ficient.

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