COLOR SCANNING SONAR

CSH-5 MARK-2

SAFETY INSTRUCTIONS

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CAUTION

Do not exceed 18 knots when operating the equipment and do not exceed 16 knots when lowering or raising the transducer.

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.

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

Use of the equipment as a stepping stool, for example, may result in personal injury or equipment damage.

A warning label is attached to the equip- ment. Do not remove the label. If the label is missing or damaged, contact

a FURUNO agent or dealer.

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TABLE OF CONTENTS

1.FOREWORD _________________________________________ 1

2.SYSTEM CONFIGURATION _____________________________ 2

3.CONTROLS _________________________________________ 3

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1. FOREWORD

The FURUNO CSH-5 MARK-2 Color Scanning Sonar is a full- circle,multibeam electronic scanning sonar which detects and instan- taneously displays fish schools and underwater conditions in 16 colors on a 14" non-glare, high resolution CRT screen. Its ease of operation, versatility and compact size make it the perfect match for any class of fishing vessel.

Some of the prominent features of the CSH-5 MARK-2 are as fol- lows;

???Compact 8" tube retraction tank

???Vivid 16-color display greatly improves recognition of seabed, and concentration, distribution and volume of fish schools.

???Various on-screen indications keep operator abreast of fishing con- ditions.

???Change of control setting is indicated by displaying the new set- ting in larger characters for five seconds.

???High power MOS FET transmitter ensures reliable operation un- der any condition.

???Control box, for operation from a distance.

The CSH-5 MARK-2 is a highly sophisticated instrument which per- forms its intended functions only when operated properly. Please care- fully read and follow the recommended procedures for operation and maintenance to take full advantage of the many features this unit has to offer.

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2. SYSTEM CONFIGURATION

System Configuration

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3. CONTROLS

Operating Controls

The CSH-5 MARK-2 provides intuitive operation. If you change a control setting you will see the associated reaction on the screen al- most immediately. All operations are carried out from the main panel and the control box. The front panel incorporates mainly controls which do not require frequent adjustment, such as brilliance, interfer- ence rejector, and audio volume. The control box, which is connected to the display unit via a 7 m-long connection cable, houses the most- often used functions, including transducer operation controls, and range and gain controls.

Main Panel

DEMAG Button demagnetizes the display for cleaning irregular picture color.

DISPLAY UNIT

CONTROL BOX

Control Panel

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Note: When the power is turned off before retracting the transducer, the transducer is automatically retracted. However, for safety purposes, do not forget to retract the transducer before turn- ing the power off.

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Control Box Panel

TRANSDUCER retracts and lower the transducer. The lamp above the switch flickers while the transducer is moving and lights when stopped.

TX turns on the transmitter, freeze the display and turns off the

transmitter. The light above the switch is on when the transmitter is turned on and flickers when off.

Note: The transmitter is turned off when the transducer is retracted even if the light above the TX switch is on.

TRACKBALL moves the trackball mark () to a desired position. The trackball mark data, i.e., slant range, horizontal range, depth and bearing to the mark, are always indicated on the screen. Additionally, this control is used to position the own ship???s mark, enter event marks and set the alarm.

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Menu Screen

The CSH-5 MARK-2 employs four menu screens; menu-l, menu-2 and system menu. Of the four menus, the menu-2 and system menu contain preset items which do not require setting alteration if they are once set at installation. See page 32 for further details. The menu-l contains items to be set by the operator while using the sonar, taking the fishing ground and fishing method into account. This menu can be recalled on the lower part of the screen as ???scan menu??? during normal operation. This let you adjust setting while observing the so- nar picture.

Recalling Scan Menu

Press the MENU key, and 5 lines of the menu items are displayed on the lower part of the screen. Note that the scan menu can be recalled only when the transmitter is on.

Changing Setting

To change a setting, select item with the RANGE control and setting with the GAIN control. The selected item is highlighted in green and the selected setting is circumscribed in white. To scroll the menu items, turn the RANGE control counterclockwise.

Note: The gain and range of the sonar picture can not be changed while the scan menu is displayed.

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Turning Off Scan Menu

To turn off the scan menu, press the MENU key.

Note: Settings for the items shown in red are locked. To unlock the settings, call up the system menu. See page 33.

List of Scan Menu Items

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4. BASIC OPERATION

General

This section provides information necessary for basic operation of the CSH-5 MARK-2, from turning the power on and off to detecting and tracking fish schools. The basic operating procedure is shown below.

Basic Operating Procedure

CONTROL SETTINGS

1/8 Turn power ON (OFF).

6Adjust gain.

3 Select display range.

Turning the Power On/Off

Power On

Press the POWER switch on the main panel. The lamp at the left of the switch lights.

Note: The Display and the Transceiver are checked for proper op- eration each time the power is applied. The check is explained in greater detail in a later chapter.

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Power Off

Press the TRANSDUCER ?????? switch on the control box. Wait until the lamp above the switch lights, and then press the POWER ???OFF??? switch. Note that the transducer automatically retracts into the tank even if the POWER ???OFF??? switch is pressed without raising the transducer (by pressing the TRANSDUCER ?????? switch). However, for safety purposes, it is recommended that you make a habit of press- ing the TRANSDUCER ?????? switch first to ensure that the trans- ducer is retracted.

Lowering the Transducer

Press the TRANSDUCER ?????? switch. The lamp above the switch flickers, and then lights when the transducer is fully lowered.

CAUTION

Observe maximum allowable ship???s speed of 18 knots during operation and 16 knots while raising/lowering transducer.

Selecting a Display Range

The RANGE switch on the control box is used to select a display range. The range selected is displayed at the top center of the screen.

Setting the Tilt Angle

The tilt angle shows the direction to which the sound wave is emit- ted. When the sound wave is emitted horizontally, it is said to be zero

(0) degrees and when emitted vertically, 90 degrees. To set a tilt angle, operate the TILT lever for the desired angle while watching the tilt angle indication at the top right-hand side of the screen. The tilt angle can be set in one-degree steps within the range of 0 to 55 degrees.

Finding the proper tilt angle is of utmost importance when searching for fish. This unit, because of its compact size, is highly suited to coastal water fishing where the depth of the main fishing ground is from 50-l00 m. In this type of fishing ground it is imperative that the seabed echo be always displayed to properly distinguish between fish and the seabed. When selecting a tilt angle, keep the following points in mind.

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Seabed Echo vs Tilt Angle

Case 1: Tilt Angle 30 to 40 degrees

A wide 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

A narrow tilt angle will display only half the seabed since it is cap- tured by only the lower half of the beam.

Case 3: Tilt Angle 0 to 10 degrees

An exceptionally narrow tilt angle may or may not capture the sea- bed since the returning echo is weak.

Example of How to Discriminate Fish Echoes from the Seabed

The following figure illustrates how two fish schools a and b are displayed on 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.

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Points to Consider

???As a general rule of thumb, a vertically distributed fish school is a better sonar target than the seabed, since it reflects the transmitted pulse back toward to the source.

???In case 3, both fish schools a and b are presented. Generally speaking, however, midwater fish schools tend to be larger than bottom fish schools and they are often displayed near the seabed on the sonar screen.

???Detection of bottom fish is difficult if they are not distributed ver- tically.

Tilt Angle for Surface Fish

Sound emitted from the sonar transducer forms a circle-shaped beam with a width of approximately 13 degrees in the vertical direction (vertical beam width). The tilt angle is indicated by the angle be- tween 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 a half of the emitted sound to be reflected back 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 will interfere with observation of wanted echoes. To minimize these sea surface reflections and to search surface fish schools effec- tively, the tilt angle is usually set to 5-6 degrees so that 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.

Suitable Tilt Angle

The figure on the next page 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.

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TILT ANGLE Tilt angle vs. Beam Coverage

Range m

Adjusting the Gain

The gain should be adjusted to see fish echoes clearly with minimal noise on the screen. Too high a setting not only causes excessive noise on the screen and makes it difficult to discriminate wanted fish echoes but also causes seabed echoes to be painted in strong colors, resulting that the echoes from bottom fish are masked by seabed re- flections. Normally, positions ???3??? thru ???7??? are used.

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5. FINE TUNING THE PICTURE

General

In the previous chapter basic operation of the sonar was presented. This chapter describes the procedures for fine tuning the sonar pic- ture.

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. To overcome this inconve- nience, the TVG function is incorporated. It compensates for propa- gation loss of sound in water; amplification of echoes on short rang 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-5 MARK-2 incorporates two TVG function, NEAR and FAR, and they mainly compensate for propagation loss on short and long ranges respectively, centered at the ranges shown below. Setting a TVG in the scan menu larger (smaller) increases (decreases) ampli- fication of echoes.

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 reflec- tions and cruising noise. To obtain the proper TVG setting, follow the procedure below.

TVG Setting Procedure

1. Set the TVG menus NEAR to ???5??? and FAR to ???5???. These are the standard setting and you can maintain these settings in most cases.

2. When sea surface reflections or plankton layers disturb the pic- ture, adjust the NEAR control to eliminate them. They will be eliminated by decreasing the control setting by ???1??? or ???2???.

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3.Locate a fish school on a long range setting which is approaching own ship. Note that the tilt should be kept adjusted so that the fish school is always placed in the center of the sonar beam, i.e., so that the fish school is displayed in strongest colors possible. Check that the fish echo is displayed in the same color while it approaches. If the color changes suddenly to weaker colors as the fish echo enters FAR and NEAR areas, the TVG is improperly set. Adjust the TVG in the scan menu to correct it. If this again produces sea surface reflections and noise, try to remove them with the AGC and NL controls as described later on.

Displaying Surface Fish Clearly

When you are searching for surface fish with the tilt set to a narrow angle, sea surface reflections may disturb or mask wanted fish echoes. In this case, in addition to the TVG adjustment described earlier adjust the AGC control between positions ???0??? thru ???3???.

Suppressing Seabed Tail

As noted earlier, fish schools (echoes) located near the seabed are sometimes difficult to detect because you have to discriminate them in the seabed reflections. The AGC control and PULSELENGTH in the scan menu, if used properly, decrease the tail of seabed reflec- tions, making it easier to discriminate bottom fish.

AGC Control

The AGC control 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 re- flections. Do not turn it too far clockwise.

PL (Pulselength)

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, i.e., ability to separate several closely lo- cated targets. When searching bottom fish, therefore, it is useful to shorten the pulselength in order to separate fish echoes from seabed reflections. Decrease the PL setting to shorten the pulselength in the scan menu. For search of surface and midwater fish in which seabed reflections are not so strong, the longest pulselength ??? 10??? should be used.

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Suppressing Seabed and Sea Surface Reflections in

Shallow Fishing Grounds

In shallow fishing grounds with hard or rocky bottom, seabed reflec- tions often interfere with wanted fish echoes and they can not be eliminated sufficiently with the aforementioned TVG and AGC con- trols, 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 setting the OUTPUT in the scan menu without turning down the gain. The picture becomes clearer when output power is reduced rather than when the gain is decreased as illustrated below.

Fish echo

Fish echo weakened

TVG & AGC adjusted No Goodwith OUTPUT

maintained high

Fish echo

OUTPUT decreased Goodwith gain maintained

constant.

Rejecting Sonar Interference and Noise

While observing the sonar picture, you may encounter occasional or intermittent noise and interference as shown below. 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

To eliminate noise effectively, you should first identify the noise source.

*Turn off the TX switch on the control box and operate all on board equipment one by one while observing the picture.

*Run the boat at various speeds to check if the noise is speed de- pendent.

If neither of the above two steps has effect on the picture, adjust the IR (Interference Rejector) and NOISE LIM (noise limiter) controls as follows.

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Rejecting Noise with IR Control

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 the IR control to positions ???1??? thru ???3??? so that noise is just eliminated. Do not use an unneces- sarily high setting since it may also reject small wanted echoes.

Rejecting Noise with NOISE LIM Control

Weak, unwanted reflections, colored light blue or green, are displayed when water is contaminated or plankton layers exist or due to ship???s noise. These echoes gradually become bluish as the NOISE LIM con- trol is turned clockwise. Usually position ???3??? to ???4??? is used.

Rejecting Interference with TX Cycle

When other sonars operate nearby at the same transmission interval as that of own ship???s sonar, interference ring caused by other sonars are displayed. To erase the interference ring from the screen, reduce the TX cycle setting on the scan menu screen. See page 8.

Note: When the sonar is used in a shallow water with the range set between 100 m and 200 m and the TX cycle at ???10???, seabed reflections caused by the transmission which is the last but one on near range on screen. Reduce the figure of TX cycle to ???7??? or ???8??? to reject them.

Interference

Selecting Horizontal Beamwidth

If you wish to have better bearing discrimination* for fish schools and also wish to examine the contour of seabed, call up scan menu and select ???narrow horizontal beam width???.

*Ability to distinguish two closely located targets at the same range and different bearings.

Selecting Vertical Beamwidth

When better detection range is required, call up scan menu and select ???narrow vertical beamwidth???.

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6. ADVANCED OPERATION

General

It this section, how to use the CSH-5 MARK-2 effectively in actual fishing operations is presented.

Measuring Range and Bearing to a Target

To measure the range and bearing to a target, use the trackball.

Procedure

1.Operate the trackball to place the trackball mark ?????? on the tar- get you want to measure the range and bearing. The range and bearing are displayed at the left top on the screen.

Trackball Mark

Slant Range

Horizontal Range

Depth

bearing

Note: The bearing is shown in either 360?? or 180?? indication system relative to the ship's heading. In the latter case, ???B??? is indi- cated as follows.

The 360?? or 180?? indication system can be selected on the menu-2.

See page 33.

Detecting Fish Schools Aurally

Occasionally you will be preoccupied with other tasks and unable to concentrate on watching the sonar picture. In such cases it would be a good choice to use the audio function. This function enables you to monitor echoes from fish schools and seabed through the built-in speaker.

After you become accustomed to utilizing the audio function, you should be able to detect a fish school from a range longer than you can detect it on the screen.

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Procedure

1.Move the trackball mark ?????? to the direction you want to moni- tor through the speaker, by operating the trackball.

2.Press the R/B key. The bearing marker will appear in the direction of the trackball mark and echoes in that direction are monitored through the speaker. Adjust the volume with the AUDIO control on the front panel.

To cover a certain area, press the SECTOR SCAN key. The bear- ing marker automatically scans in 2?? steps starting from the bearing set at step 2 to cover the selected sector, giving you audio in the di- rections of 2?? steps.

To change the coverage area call up scan menu, and then select an auto scan width with the GAIN control; ??10 ?? , ??20 ?? , ??40 ?? , ??60 ?? .

To turn off the audio function, erase the bearing marker by placing the trackball mark on own ship mark and then pressing the R/B key.

Trackball Mark

Bearing Marker

Auto Scan Width

Own Ship Mark

Relocating Fish School for Easy Observation

When a fish school is located near the edge of the screen and incon- venient for observation, use the off-center function to relocate the fish school to the desired place on the screen.

Fish School

Fish School

Off-center "ON"

Own ship Mark

Trackball Mark

Procedure

1.Move the trackball mark ?????? to the position where the own ship mark is to be moved.

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2.Press the OFF-CENTER key on the front panel.

3.To move the own ship mark back to the center of the screen, press the OFF-CENTER key again.

Finding Fish School Center

When you want to find the center depth of a fish school, use the auto tilt function which automatically scans the tilt angle within the se- lected width.

Procedure

1.Call up the scan menu, select the menu item ???AUTO TLT WDTH??? and then choose a tilting width. The center tilt angle of the scan- ning is set by the TILT lever.

Both center and current tilt angles are displayed along with the range data at the upper right corner on the screen.

Registering F1/F2 (function) key and Recalling

Function keys provide user defined sonar settings by one key opera- tion.

Default setting

These keys are preset at factory for one key operation as follows;

Three magnetic function cards are supplied for indication of function settings. Two of these cards are inscribed with the factory setting of F1 and F2. The other card is blank for recording user settings. You can attach the card on the main panel for reference. See page 10.

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Registering Procedure

1.Press the MENU key.

2.Rotate the RANGE control to select FUNC KEY PROG.

3.Rotate the GAIN control to select FUNC1 or FUNC2.

4.Press the TX key. Each time the TX key is pressed, the current settings in the scan menu and E/S menu are recorded.

When FACTORY is selected, the default value is displayed.

Recalling Procedure

1.Press F1 or F2. Presetting function is recalled and function indi- cation (LED lamp) lights.

Canceling the recalling

1. Press F1 or F2 again. The LED lamp goes off.

Recommended Settings

We recommend the function key be set as follows,

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7. MARK AND DATA

BEARING MARK

RANGE MARK

TRACKBALL MARK

HEADING MARK

OWN SHIP MARK

RANGE RING

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Data

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8. INTERPRETING THE DISPLAY

General

This section provides information necessary for interpreting the display.

Interpreting the Display

Seabed

When the tilt angle is changed, the seabed echo illustrated below will appear on the screen. When the tilt angle is decreased, the seabed trace becomes wider and weaker. By observing the seabed condition on the screen, the skipper can prevent the net from being damaged by a reef or a shipwreck.

(a) Flat Seabed

Tilt Angle: 10?? - 15??

Seabed

Echo

Narrow tilt angle; only half of vertical beam width captures the seabed.

Seabed

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Fish School

A fish school appears as a mass of echoes on the screen. The color of the mass shows the density of fish schools on the sonar beam. To know the distribution and center point of a fish school, the tilt should be changed to several different angles.

(a) Sea Surface Fish

Tilt Angle: +5?? - 10??

(b) Midwater, Bottom Fish

Fish echo appears before seabed echo

Tilt Angle: 30?? or more

Seabed

Fish school

Large midwater fish school is present.

Seabed

Since the seabed is displayed in weak echo colors, longer range detection and detection of close to bottom fish school become possible.

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Sea Surface Reflections

To reduce the sea surface reflections, set the tilt angle to 5?? or more so that the upper edge of the sonar beam may not hit sea surface, or adjust TVG functions. When the sonar is used with a narrow tilt angle, the sea surface reflections cover large area (up to 300 m to 400 m) as illustrated below.

Sea Surface

Reflection

SEA SURFACE

Tilt Angle 5?? - 6?? 13??

Wake

Awake produced by own ship or another ship can be a strong reflect- ing object when the sonar is used with a narrow tilt angle. As the wake appears on the screen as a thick continuous line, it can be easily distinguished from a fish school. On the other hand, the wake con- tains a lot of air bubbles which attenuate ultrasonic energy, making it often difficult to sound beyond the wake.

Other Ship

Own Ship???s

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False Echo by Sidelobe

In the preceding chapters, it was explained that an ultrasonic wave is emitted only in the direction set by the TILT lever, but, in practice, there are some emissions outside the main beam that are called ???sidelobes???. Energy of the sidelobe is fairly weak but when the sonar is used in comparatively shallow water with a hard and rocky bot- tom, strong target signals are detected by the sidelobe. These are rep- resented on the screen as a false echo as shown below. To weaken the sidelobe echoes, set the VER BEAM ANGLE to WIDE on the SCAN MENU.

Mainlobe echo

Sidelobe echo

The seabed echo detected by sidelobe appears at a certain tilt angle when the sidelobe points vertically.

Noise and Interference

In case the fishing ground is crowded with many fishing boats, the sonar is subject to interference from ultrasonic equipment such as an echo sounder, sonar, etc. on board other boats as well as those on board own ship.

For instance, interference from the sonar operated on board other boats will appear as a ring as shown in (A). This interference can be suppressed by properly changing TX cycle. Electrical equipment on own ship can also cause interference to the sonar as shown in (B). The noise from some marine life appears on the screen as in (C). This noise can be suppressed by the IR control.

Noise and Interference

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9. WARNING

Overvoltage Warning

If the supply voltage rises about 20% to over the rated value, the overvoltage detection circuit is actuated. The following warning flick- ers at the center of the screen and an alarm sounds.

OVERVOLTAGE!

If this occurs, retract the transducer, turn the POWER off and check the ship???s mains (and the stepdown transformer if provided).

Unretracted Transducer Warning

When the transducer can not be completely retracted within 35 sec- onds after pressing the TRANSDUCER ?????? switch, the following warning flickers at the center of the screen and an alarm is released.

XDCR NOT RETRACTED!

If this occurs, do the following.

1.The POWER switch can not be turned off because the transducer can not be retracted. Turn off the main breaker for the transceiver unit to stop operation.

2.Confirm that the net is not entwined around the transducer.

3.Confirm that the breaker inside the raise/lower control box mounted on the hull unit is ???ON???.

4.Check the mains fuse in the transceiver unit.

5.Apply the power again and confirm that the transducer is retracted into the tank. If not, the main shaft of the hull unit may be bent. Cut off the power again and manually raise the transducer up to the highest position by using the hand crank attached to the hull unit.

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10. MENU

General

The CSH-5 MARK-2 employs three menu screens, menu-1 menu-2, and system menu, to preset infrequently used functions.

Changing Menu Settings

Procedure to Change Menu Settings

1.Turn off the transmitter with the TX key; LED flickers.

2.Press the MENU key. The menu-1 appears.

3.To select another menu, operate the GAIN control.

4.Select a menu item with the RANGE switch and change the set- ting with the GAIN control.

Note: Setting for the items shown in red are locked. To unlock the settings, change the ???menu select??? setting on the system menu.

Menu-1

The figure below shows menu-1.

The contents of the menu-1 are same as the scan menu described on page 8.

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Menu-2

The figure below shows menu-2.

System Menu

The figure below shows the system menu.

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11. INTERFACE MODULE CSH-5060

Specifications

The CSH-5060 Interface Module permits connection of external equip- ment (navigational equipment, current indicator, echo sounder, net sonde, gyrocompass, log, etc.) to display various data on the CSH-5 MARK-2.

1. Display Mode

(a)Normal

(b)Normal + Text

(c)Echo Sounder Combination (Normal + Echo Sounder)

(d)Sonar Combination (Normal + Signal on R/B Mark)

2. Display Mark

Course line mark, Current mark, Event mark, Electronic bearing scale,

Heading mark, and Net sonde data are graphically displayed on the

Echo Sounder Combination mode.

3. Numeric Information

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Operation

The functions of the Interface Module are accessed from the MENU screen except the Event mark and North mark*.

* ???Gyrocompass required.

1. Event Mark and Own Ship Mark

Plotting

(1)Move the cursor to the location where you want to plot the event mark.

(2)Press the EVENT key. The cursor is replaced with the latest

OFF-

F2

CENTER

LED lamp

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3. Erasing Weak Noise

Unknown weak noise appearing over the entire screen can be erased with DELETE COLOR, on the SCAN menu. Echoes are erased in order from weakest to strongest, so you may use this function to show only strong echoes.

1.Press the [MENU] key to turn on the menu.

2.Select DELETE COLOR with the RANGE control.

3.Use the GAIN switch to select desired setting. The setting range is 0-10. "0" turns off this function, 10 erases the strongest color echoes. Note that the echoes on the echo sounder and range and bearing mark display will also be erased.

4.Press the [MENU] key to close the menu.

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4. Suppressing Effects of Pitching and Rolling

The Motion Sensor MS-100 (option) compensates for the effects of pitching and rolling to provide stable sonar pictures. You may enable it as follows:

1.Press the [MENU] key to display the SCAN menu.

2.Use the RANGE control to select RANGE/BEARING.

3.Use the GAIN control to select STAB.

4.Press the [MENU] key to close the menu.

5.Operate the trackball to place the trackball mark on the bearing you want to compensate by the MS-100.

6.Press the [R/B] key. A dashed line appears at the bearing selected at step 5. The rolling and pitching of the ship in the direction of the bearing mark is compensated, by automatically adjusting the tilt angle.

Picture in direction selected with bearing mark is compesnated.

Note: The entire picture is not compensated in the full-circle scan- ning; the tilt angle for each bearing cannot be changed. Only one bearing is compensated and bearing error will result for any bearing not stabilized.

Tilt can be controlled manually from 0?? to 55??, however rolling and pitching are compensated from -5?? to 55?? with the tilt angle at ??20??.

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5.Detecting Fish Echoes in Specific Area (Fish Alarm)

The fish alarm alerts you to fish echoes in an area you select. Any fish echoes entering the area will trigger the audio alarm. The fish echo level which triggers the alarm may be selected from the scan menu.

1.Press the [MENU] key to open the SCAN menu.

2.On the scan menu, use the RANGE control to select RANGE/

BEARING.

3.Use the GAIN control to select FISH/ALM.

4.Use the RANGE control to select FISH ALARM.

5.Use the GAIN control to select ON.

6.Press the [MENU] key to close the menu.

7.Use the trackball to place the trackball mark on the starting bear- ing and press the [R/B] key.

8.Use the trackball to place the trackball mark on the ending bear- ing and press the [R/B] key.

Alarm area

Starting point

Ending point

To disable the fish alarm, press the [R/B] key.

Note: The starting point may be selected at the outside or inside of the alarm zone. You may also set a 360-degree alarm by set- ting the starting and ending points within three degrees of each other as in (c) and (d) in the figure below.

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8. Menu Description

The CSH-5 MARK-2 employs three menu screens, MENU-1, MENU- 2 and SYSTEM Menu, to preset infrequently used functions. During normal operation (transducer lowered, transmitter ON), the SCAN Menu appears on the screen. This lets you adjust settings while ob- serving the sonar picture.

9. Menu Screen Indications

MENU-1

:indicates the items which may be locked.

:indecates the menu items available with the addition of the CSH-5060 and external equipment.

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MENU-2

SYSTEM MENU

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SCAN MENU

E/S MENU

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10. Contents of Menu Items

This section describes the menu items available with the addition of the CSH-5060 and external equipment.

MENU-1 (SCAN, E/S Menu)

Scan menu

44

E/S Menu

Depth unit may be selected on the SYSTEM Menu.

45

MENU-2 (Refer to pages 47 to 51 for location on the screen.)

46

Indications

1. Normal Mode (NORM)

4

2

1

6

5

3

6

47

2. Normal + Text Mode

!0

48

3. Echo Sounder Combination Mode (COMBI 1)

Normal + Echo Sounder

Sonar

Picture

Echo

Sounder

Picture

16 Color Bar

49

4. Sonar Combination (COMBI 2)

Normal + Signal on R/B Mark

Sonar

Picture

Signal on

R/B Mark

16 Color Bar

50

Marks and Data

This section explains the Marks and Data available from the equip- ment interfaced. Pages 24 to 25 show the location of these Marks and Data.

51

Event Mark Position Output

Connected to a navigator, the CSH-5 MARK-2 can output event mark position data to external equipment when the [EVENT] key is oper- ated. The data sentence output is "SSTLL" (NMEA, IEC-1162 for- mat).

52

12. MAINTENANCE

General

The CSH-5 MARK-2 is designed and constructed to provide many years of trouble-free performance when properly maintained. User- performable maintenance and important points to be observed are outlined in the figure below.

WARNING

cleaning. Use a water-moistened softDisplay Unit cloth.

Keep magnets and cassette tapes away!

Hull Unit

53

13. UNIT DIAGNOSTIC TESTS

This unit has eight built-in diagnostic tests which check it for proper performance. Although the tests are designed primarily for use by the service technician, they can also be executed by the user to identify defective components. However, never attempt to check inside the unit; there are no user-serviceable parts inside. Any repair work is best left to a qualified technician.

Turning-on/off Diagnostic Test

1.Press the MENU key, and then select the system menu by operat- ing the GAIN control.

2.Select the ???SELF-TEST??? function by operating the RANGE switch. Select an appropriate self-test by operating the GAIN control.

3.Press the TX switch to execute the self-test.

4.To exit from the self-test screen, press the MENU key for a few seconds. When the ???SINGLE??? is selected, the unit automatically restores the system menu after the test is completed.

Description of Unit-diagnostic Tests

Single Test

This test checks the Main Board and Transceiver Unit for proper op- eration one time, after which normal operation is restored. After the test is completed, the results are indicated as OK (normal operation) or NG (malfunction), to the right of the device checked.

54

Conti Test

This is a continuous test of the Display and Transceiver Units. Addi- tionally checked devices are DROM and DRAM.

Panel Test

This test checks the controls on the front panel and the control box for proper operation.

PRESS [MENU] 2 or 3 SECONDS TO STOP SELFCHECK

SIO Test

This test checks the input/output parts of the Transceiver Unit. The results of the test are indicated as OK or NG.

PRESS [MENU] 2 or 3 SECONDS TO STOP SELFCHECK

55

Color Test

The color test checks for proper display of all colors.

COLOR TEST

16 Color display

WHT RED GRN

PRESS [MENU] 2 or 3 SECONDS TO STOP SELFCHECK

Echo-1 Test

The echo-1 test checks echo processing circuits in the display unit for proper operation.

DISPLAY ECHO TEST

R29 B358??

PRESS [MENU] 2 or 3 SECONDS TO STOP SELFCHECK

56

Gray Test

The gray test checks for proper display of monochrome characters and markers. Concentric rings and a monochrome test bar are dis- played.

GRAY TEST

............

PRESS [MENU] 2 or 3 SECONDS TO STOP SELFCHECK

Echo-2 Test

The echo-2 test checks echo processing circuits in the transceiver and display units.

PRESS [MENU] 2 or 3 SECONDS TO STOP SELFCHECK

Set the VP control on the main panel to "OFF" position. Radial pattern as above is displayed.

57

14. CHARACTERISTICS OF THE

ULTRASONIC WAVE IN WATER

The purpose of this chapter is to provide an overview of the charac- teristics of the ultrasonic wave in water.

Sound Velocity

It is generally known that an ultrasonic wave travels 1500 meters per second in sea water, but in practice, some amount of variation arises depending on the season and area from differences in the following three factors:

Therefore, for propagation in surface water the velocity changes not only by area but also by direction of the wave propagation. The equa- tion obtained thru numerous measurements is;

C= 1410 + 4.21?? - 0.037?? 2 + 1.145S + 0.0168h [m/s]

58

Research in the waters throughout the world has revealed that there is a difference of approximately 100 m/s between the areas where the velocity is maximum and minimum

Generally, the velocity increases as follows, provided that salinity density is constant:

???3 m/s for every 1 degree rise of water temperature

???1.7 m/s for every 100 m increase of water depth

Absorption and Attenuation

An ultrasonic wave emitted into water becomes weaker in intensity as it goes away from the emitting source. Principle causes of attenu- ation are:

1.Acoustic energy of the ultrasonic wave decreases gradually through reflection, refraction and diffusion in water.

2.Acoustic energy is absorbed by the viscosity of the medium (wa- ter) and converted into other forms of energy.

The higher the frequency, the greater the absorption and attenuation of the ultrasonic wave as shown below. In other words, the absorp- tion coefficient is a function of the frequency. Generally, total energy loss encountered on the way to and from a target is expressed

59

Refraction

An ultrasonic wave transmitted in water does not travel straight but is more or less refracted. This refraction is caused by the variation of propagation velocity in water. If the velocity decreases (temperature decreases) with depth, the top part of the wave front moves faster than its bottom part, and gradually the front bends downwards. In the same way, it bends upwards if the sound velocity increases (tempera- ture rises) with depth.

In other words, the ultrasonic wave refracts toward colder water.

Here, a fishing ground off Hokkaido island in Japan is taken as an example.

Seaface

Large difference in density

Fishing Ground off Hokkaido (Summer)

In summer, there is a large difference in salinity density below and above the 100 m deep point. An ultrasonic wave emitted almost in the horizontal direction propagates within 100 m deep water in the same way as a radio wave in a waveguide. As a result, even a small fish school is sometimes detected at an unexpected long range or on the contrary, detection of a large fish school does not extend to a relatively long range. These phenomena are encountered when two fish schools lie in positions ???A??? and ???B??? of the illustration.

60

Adverse Effect of Air Bubbles

Even infinitesimal air bubbles in sea water (liquid medium) affect propagation of ultrasonic sound. This is because the cubic elasticity of gas is extremely small when compared with that of liquid; the air bubbles violently vibrate (contract and expand) by the action of sound pressure, diffusing the ultrasonic wave and dispersing part of the acoustic energy. In a liquid which contains a large amount of air bubbles, attenuation of an ultrasonic wave increases and the wave is reflected at the boundary of waters which contain and do not contain air bubbles.

From the above it can be said that reflection occurs in the boundary where the density (P) of the material (medium) that is, the velocity of the ultrasonic wave changes. The velocity of an ultrasonic wave with respect to its medium is 200 thru 400 m/s in gas, except for hydrogen and helium; 900 thru 2000 m/s in liquid (several times higher than in air) and 2000 thru 6400 m/s in ordinary metal.

61

The product of the density (P) and the velocity (C) is called intrinsic acoustic impedance and in the boundary between two media which has extremely different C from each other, most of the acoustic power is reflected and only a small portion penetrates. (In the boundary be- tween water and air, the acoustic energy penetrates with a loss of approximately 30 dB, that is approximately 0.1 % of the energy pen- etrates from one medium to the other.)

Reflection from water which contains air bubbles is caused by the fact that the cubic elasticity decreases in aerated water, causing the intrinsic acoustic impedance to change.

In the actual sonar operation, adverse effect of air bubbles is shown by interrupted display of target echoes which occurs while crossing over the wake of another boat or when the sonar transducer passes above the air bubbles generated by own ship.

Air bubbles in water have a resonant frequency of l5 kHz thru 100 kHz and hence the ultrasonic wave in this frequency range is most strongly affected.

Reflection at Seabed and Fish School

The nature of the seabed is roughly classified into the following four kinds: crag, sand, mud and seaweeds. In addition, shells and carcass of animals (especially coral) imbedded in the seabed cause reflection loss.

The actual reflection loss in the sea is shown below. The reflection loss remains almost constant up to 50 kHz and then gradually in- creases.

The relation of frequency vs reflection loss for mackerel is shown below. The calculated value and actually measured value nearly co- incide. And also, on the contrary to the seabed reflection, the reflec- tion loss decreases as the frequency increases. The ???K??? in the figure is the coefficient of fish shape, where its larger value introduces smaller reflection loss.

62

63

SPECIFICATIONS

1. Display

PPI display on 14" non-glare, high resolution color CRT

2. Display Color

16 colors according to echo strength

3. Numeric information

4. Range/Pulselength

Range

NOTE: 1. Ranges shown for off-center ???on??? are maximum.

2.Under certain circumstances, a target (fish school) may not be detected due to its nature or because of sea conditions, even if it is located within the display range.

SP-1

5. AUDIO SEARCH

6. Transmitter/Receiver

7. Tilt Angle

8. Hull Unit

9. Other Features

Interference Rejector, Video Processing, Noise Limiter, Automatic Tilt Scanning Overvoltage Warning, Unretracted Transducer Warn- ing

10. Power Supply, Power Consumption

100/115/200/240VAC, 50/60Hz, 1?? , 0.4kVA on average, 1kVA max. 24/32VDC with optional DC-AC inverter CSH-5050.

SP-2

INDEX

Index-1

S

Scan menu 8

Sea surface reflections 28

Seabed echo 26

SECTOR SCAN key 6, 21

Sidelobe 29

Single test 54

SIO test 51

Sound velocity 58

System configuration 2

System menu 33

T

Tilt angle

and discriminating fish echoes from bottom 12 for surface fish 13

general selection 11 TILT lever 5, 11 Trackball 5

TRANSDUCER switch 5, 11, 30 TVG adjustment 16

TX cycle 19

W

Wake recognition 28

Index-2