Furuno CSH-73 User Manual
COLOR SCANNING SONAR
MODEL
CSH-73
9-52 Ashihara-cho,9-52 Ashihara-cho,
A
A
*00080806200**00080806200*
*00080806200**00080806200*
*OME13080C00**OME13080C00*
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.
ll rights reserved.
PUB.No.PUB.No. OME-13080OME-13080
(( DAMIDAMI ))
CSH-73CSH-73
Printed in JapanPrinted in Japan
FIRST EDITION :FIRST EDITION : OCT.OCT. 19971997
C :C : APR.APR. 05,200205,2002
* 0 0 0 8 0 8 0 6 2 0 0 ** 0 0 0 8 0 8 0 6 2 0 0 *
*OME13080C00**OME13080C00*
* O M E 1 3 0 8 0 C 0 0 ** O M E 1 3 0 8 0 C 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.
iiiiiiiiiiiii
i
TABLE OF CONTENTS
FOREWORD
A Word to CSH-73 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
OPERATIONAL OVERVIEW
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.................................................................................................................2-4
Measuring Range and Bearing to a Target.............................................................................2-4
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
Adjusting Beamwidth ............................................................................................................3-7
MARKS AND DA T A
Marks, Data and Display Mode.............................................................................................4-1
Permanently Displayed Marks and Data ...............................................................................4-3
Erasable Marks and Data .......................................................................................................4-4
USER MENU OVERVIEW
USER Menu Operation..........................................................................................................5-1
USER Menu Description .......................................................................................................5-3
ii
FUNCTION KEYS
Programming the Function Keys ...........................................................................................6-1
Replaying a Function Key .....................................................................................................6-2
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 (target lock)......................................................................................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
Setting Distances Between Net Sonde Transmitters............................................................7-16
Observing Net Behavior ......................................................................................................7-17
Port/Starboard, Horizontal Slice Displays...........................................................................7-18
Turning Marks, Data On/Off ...............................................................................................7-20
SAVING, REPLAYING PICTURE
Initializing Memory Cards.....................................................................................................8-1
Saving the Picture..................................................................................................................8-2
Transferring Echo Data from Internal Memory to Memory Card.........................................8-2
Saving Net Shooting Data .....................................................................................................8-3
Replaying Saved Data ...........................................................................................................8-4
Deleting Memory Card Contents...........................................................................................8-4
INTERPRETING THE DISPLAY
Seabed Echoes .......................................................................................................................9-1
Fish Schools...........................................................................................................................9-2
Sea Surface Reflections .........................................................................................................9-3
Wake ......................................................................................................................................9-3
False Echo by Sidelobe..........................................................................................................9-4
Noise and Interference...........................................................................................................9-4
WARNINGS
Overvoltage Warning ...........................................................................................................10-1
Unretracted Transducer W arning.........................................................................................10-1
iii
SELF TESTS
Opening the Self Test Menu ................................................................................................11-1
Self Test Description............................................................................................................11-2
Interface Unit CS-120A Self Test ........................................................................................11-5
MAINTENANCE
Display Unit Maintenance ...................................................................................................12-1
Hull Unit Maintenance ........................................................................................................12-2
SPECIAL MENU DESCRIPTION
SYSTEM Menu Description ...............................................................................................13-1
DATA SET Menu Description .............................................................................................13-4
INIT SET/TEST Menu Description.....................................................................................13-7
MENU TREE..................................................................................................................A-1
SPECIFICATIONS..................................................................................................... SP-1
INDEX.............................................................................................................................. IN-1
iv
FOREWORD
A Word to CSH-73 Owners
Congratulations on your choice of the FURUNO CSH-73 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-73 Color Scanning Sonar is a half-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-73 are
• Vivid 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.
v
System Configuration
STANDARD
REMOTE CONTROL BOX
CSH-116
SHIP’S MAINS
100 VAC, 1φ,
50/60 Hz
TRANSCEIVER UNIT
CSH-710
DISPLAY UNIT
CSH-731
INTERFACE UNIT
CS-120A
OPTION
REMOTE DISPLAY
CSH-106
110/115/220/230 VAC,
1φ, 50/60 Hz
IE/S NTERFACE UNIT
SUB DISPLAY
CSH-736
SHIP’S MAINS
100 VAC, 1φ,
50/60 Hz
STEP-DOWN
TRANSFORMER
PT-400
SPEED LOG
AD CONVERTER
NAVIGATOR
CURRENT INDICATOR
COLOR VIDEO SOUNDER
VI-1100A
SHIP’S MAINS
100/110/220 VAC, 1φ,
50/60 Hz
HULL UNIT
CSH-71080 ( 800 mm stroke)
CSH-71120 (1200 mm stroke)
including POWER SUPPLY UNIT
CSH-720
FNZ JOINT BOX
CS-170
E/S INTERFACE UNIT
ECHO SOUNDER, COLOR
VIDEO SOUNDER
NET SONDE
vi
CONTROL DESCRIPTION
Control Layout on Display Unit and Remote Control Box
PUSH-OPEN
SUB PANEL 2
OFF
AUTO
TRAIN
WIDTH
NET
COURSE
EVENT1
ESTI-
MATE1
FISH
POWER
RANGE
TARGET
EVENT2
ON
+-
TRAIN
LOCK
DIM CONT BRILL AUDIO
ESTI-
MATE2
OFFCENT
TRANSDUCER
F3F2F1
TILT
RECALL
SUB PANEL 1
-
+
MEMOHISTE/SNORM
+-
GAIN
AUTO
TILT
WIDTH
MAIN PANEL
DISP SELECT
1
EVENT
TGT LOCK
ESTIMATE
NET COURSE
1
FISH
1
234
+
–
RANGE
AUTO
TRAIN
OFFCENT
2
d
FUNCTION
+
–
GAIN
dc
TGT
SLICE
AUTO
BOOST
3
SHOOT
DATA
TX
MEMO
RECALL
TILT
SCAN DEPTH
5
REMOTE CONTROL BOX
Figure 1-1 Display unit and
remote control box
1-1
Main Panel
OFF
AUTO
TRAIN
POWER
RANGE
ON
TRANSDUCER
F3F2F1
+-
-
RECALL
GAIN
MEMOHISTE/SNORM
+-
AUTO
TILT
+
WIDTH
NET
COURSE
EVENT1
ESTI-
MATE1
FISH
TRAIN
TARGET
LOCK
EVENT2
ESTI-
MATE2
OFF-
CENT
TILT
DIM CONT BRILL AUDIO
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.
TRAIN Rotates the transducer. The center of the sounding beam can be
AUTO TRAIN
WIDTH
TILT Changes the tilt angle of the sounding beam between 0°and 90°.
AUTO TILT,
WIDTH
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.
oriented in any direction between 165° port and 165˚ starboard.
Press AUTO TRAIN to train the transducer automatically within
±30°, ±60°, ±90° or ±120° sector as selected with the WIDTH key.
The lamp above the switch lights during the automatic training
operation.
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.
NET COURSE Marks location of net.
TARGET LOCK Tracks a fish school.
EVENT , Inscribe event mark on the display, to find horizontal range, depth and
bearing to a target. Note that the EVENT key can function the
same as the SHOOT key of the remote control box. This can be done
on OTHER sub-menu in the INIT/SET menu
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
MEMORY CARD
DRIVE
CARD EJECT
BUTTON
Figure 1-3 Sub panel 1
Sub panel 1 control description
POWER
OFF
ON
CARD
REPLAY
COLOR
TRANSDUCER
MENU
END
HELP
NET
REPLAY
F4
RECALL
TX
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
ES
DELETE MK
AUTO
ALM•AUDIO
g
h
CURRENT SETTINGS for item selected (TVG•TX)
NEAR7MEDIUM
+ + + + + +
– – – – – –
Item selection keys
Select item.
TVG TX
8
FAR
9
Setting change keys
Change control setting.
CYCLE
7
PL
8
OUTPUT
9
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
5
5
5
9
9
(Continued on next page)
OUTPUT 0–9
Sets Tx output power. 9 is
maximum power.
9
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
0
0
SIGNAL
ES
SIGNAL
PROCESS
ES1
(Net
Recorder)
ES1
(Net
Recorder)
Selects echo level versus presen-
CURVE 1–4
IR 0–3
AFGLOW 0–4
RANGE
(DN RNG)
GAIN 0–10 Adjusts receive sensitivity. 5
SHIFT
(UP RNG)0–1000 m
NL 0–10
COLOR 0–9
IR
16
Pos.
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
2
0
0
0
0
Each pressing erases oldest mark
among event mark , event
mark , fish mark, own ship
mark.
Each pressing deletes 1/5 of
overall length of ship's track. If
target lock function in on, sixth
pressing deletes the fish school
track and cancels target lock
mode.
DELETE MK
DELETE
MARK
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)
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*HOR and 2AGC functions cannot be used together. If one is used the other is
automatically set to “0”.
01
03 °
0
1-7
Remote Control Box
e
elects which display unit to
ontrol in multiple display unit
stallation.
ises/lowers the transducer.
Raises transducer.
Mid protrusion
Full protrusion
Press to enter mark
shown on key or shift
screen center.
Selects display range.
Adjust receiver sensivity.
Trains the transducer
automatically within a
selected sector.
ts direction of the sounding
am center between 165ß port
d 165ß starboard.
1
EVENT
ESTIMATE
1
FISH
1
+
–
RANGE
DISP SELECT
FUNCTION
+
3
dc
SHOOT
2
d
TGT LOCK
NET COURSE
OFFCENT
234
–
GAIN
AUTO
TRAIN
TGT
SLICE
AUTO
VERT SCAN
DATA
TX
5
MEMO
RECALL
TILT
SCAN DEPTH
Each press displays water
temperature or depth at screen
center for about five seconds.
Turns on transmitter. Press this
key for more than one second for
stable operation.
Shifts trackball mark.
1-3: Same as 1-3 on main panel.
4-5: Same as - and + on main pan
Displays net shooting mark.
Saves picture to memory card.
Not used.
Replays a stored picture.
Automatically tillts sounding
beam in 2¡ steps within sector
selected by WIDTH key.
Varies the tilt angle of the
sounding beam between 0¡
and 90¡.
Not used.
1-8
Figure 1-5 Remote control box
OPERATIONAL OVERVIEW
CAUTION
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
d
or d switch during raising
of the transducer.
The equipment may become damaged.
Turning the Power On/Off
Turning the power on
Press the ON key 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 key and then press the OFF
key on the main panel.
Note: The transducer is automatically retracted into the tank even
if the OFF key 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 Transducer
Press d(full) or d(mid) key. 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
This raises the transducer by 400 mm (transducer extends 800 mm* from ship’s hull).
d(mid) key.
*: Hull unit with 800 mm (full) and 450 mm
(mid) protrusion is also available.
2-1
Selecting a Display Mode
The CSH-73 provides three display modes: normal sonar picture, echo sounder (E/S) 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. Two types of history displays are
available: Audio and Port/Starboard.
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 T ilt 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 0 to 90 degrees.
Finding a proper tilt angle is important when searching for fish.
The beam of the half-circle scanning sonar is fan shaped as in
(A) below and it swings up and down according to the setting of
the TILT lever. If you look at the angle between the horizontal
plane (sea surface) and several points on the beam, it can be
seen that the angle is maximum in the center of the beam (q) and
becomes smaller as it goes toward the edge, finally becoming
zero degrees at the edge of the beam. This will be more clearly
understood if you look at a vertically directed beam. See (B)
below. You should keep in mind that the tilt angle displayed on
the screen is the angle the center of the beam forms with the
horizontal plane.
θ
(A) (B)
Figure 2-1 Tilt angle
SEA SURFACE
2-3
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 Gain high
Figure 2-2 Gain settings and resulting pictures
Measuring Range and Bearing to a Target
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.
ª
ª
ª
B
Figure 2-3 Location of range and bearing indications
2-4
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
FINE TUNING THE PICTURE
This chapter provides the information necessary for tuning the
sonar picture. All operations are performed on sub panel 2 (data
setting window).
Sub Panel 2
Figure 3-1 Display unit
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-73 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
in the figure on the next page. The higher the TVG setting the
greater the amplification of echoes.
3-1
Near
25 m
Med
100 m
Far
400 m
Figure 3-2 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 (default setting).
There setting are useful for almost cases.
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 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 25 log setting is useful for searching fish schools near shorelines or shallow waters.
3-2
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.
3-3
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
Seabed echo
False seabed echo
Surface echo
Fish echo
Figure 3-3 How to suppress seabed and sea surface reflections
in shallow waters
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.
3-4
Interference from
other sonar
Cruising (propeller)
noise of own ship
Cruising noise
from other boat
Figure 3-4 Forms of interference
Identifying noise source
T o eliminate noise effectively , you should first identify the noise
source as follows:
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. T o erase the interference ring from the
screen, reduce the CYCLE on the data setting window.
3-5
Interference
Figure 3-5 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.
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 sufficient.
3-6
Adjusting Beamwidth
Beamwidth can be adjusted at SONR•BEAM, BEAM on the
data setting window .
Table 3-1 Beamwidth adjustment menus
Menu Application
HOR
Set to "0" for normal use. The higher the setting the
narrower the beam. This control may be used
together with the AGC and NL controls to suppress
sea surface reflections and seabed echoes.
3-7
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MARKS AND DATA
Marks, Data and Display Mode
Normal display mode
Figure 4-1 Marks and data appearing in the normal display
mode
4-1
Normal display mode w/text
Figure 4-2 Marks and data appearing in the normal display
mode w/text
Echo sounder combination
display
4-2
Figure 4-3 Marks and data appearing in the echo sounder
conbination display mode
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