Furuno 841 MARK-2 User Manual
MARINE RADAR
MODEL
MODEL 841 MARK-2
(
C
9-52, Ashihara-cho,
Nishinomiya, Japan
Telephone: 0798-65-2111
Telefax: 0798-65-4200
All rights reserved.
Printed in Japan
Your Local Agent/Dealer
FIRST EDITION : JAN. 1997
G : JUL. 10, 2001
PUB. No. OME-34440
HIMA)
MODEL841 MARK-2
SAFETY INSTRUCTIONS
"WARNING" and "CAUTION" notices appear throughout this manual. It is the responsibil-
ity of the operator and the installer of the equipment to read, understand and follow these
notices. If you have any questions regarding these safety instructions, please contact a
FURUNO agent or dealer.
The level of risk appearing in the notices is defined as follows:
This notice indicates a potentially
hazardous situation which, if not
WARNING
CAUTION
avoided, could result in death or
serious injury.
This notice indicates a potentially
hazardous situation which, if not
avoided, could result in minor or
moderate injury, or property damage.
iiiiiiiiiiiii
i
Safety Instructions for the Operator
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.
Wear a safety belt and hard
hat when working on the
antenna unit.
Serious injury or death can
result if someone falls from
the radar antenna mast.
Stay away from transmitting
antenna.
The radar antenna emits microwave radiation which can
be harmful to the human body,
particularly the eyes. Never
look directly into the antenna
radiator from a distance of
less than 1 m when the radar
is in operation.
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.
WARNING
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.
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.
Continued use of the equipment can
cause fire or electrical shock.
ii
Safety Instructions for the Installer
Ground the equipment to
prevent electrical shock
and mutual interference.
Confirm that the power supply voltage
is compatible with the voltage rating
of the equipment.
Connection to the wrong power supply
can cause fire or equipment damage. The
voltage rating appears on the label at the
rear of the display unit.
Use the correct fuse.
Use of a wrong fuse can cause fire or
equipment damage.
CAUTION
WARNING
Do not work inside the
equipment unless totally
familiar with electrical
circuits.
Hazardous voltage which can
cause electrical shock, burn or
serious injury exists inside the
equipment.
Wear a safety belt and hard
hat when working on the
antenna unit.
Serious injury or death can
result if someone falls from
the radar antenna mast.
If applicable, turn off the
power at the mains switchboard before beginning the
installation. Post a sign
near the switch to indicate
it should not be turned on
while the equipment is
being installed.
Fire, electrical shock or
serious injury can result if the
power is left on or is applied
while the equipment is being
installed.
iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii
iii
TABLE OF CONTENTS
FOREWORD................................ v
SPECIFICATIONS ..................... vii
EQUIPMENT LIST ...................... ix
CONFIGRATION......................... xi
1. PRINCIPLE OF
OPERATION............................. 1
1.1 What is Radar? ................................. 1
1.2 How Ships Determined Position
Before Radar..................................... 1
1.3 How Radar Determines Range ......... 1
1.4 How Radar Determines Bearing....... 1
1.5 Radar Wave Speed and Antenna
Rotation Speed.................................. 1
1.6 The Radar Display ............................ 1
2. OPERATION
2.1 Control Description .......................... 3
2.2 Display Indications and Markers...... 4
2.3 Turning the Radar On and Off .......... 4
2.4 Transmitting...................................... 5
2.5 Selecting the Range .......................... 5
2.6 Adjusting LCD Backlighting and
Display Tone..................................... 5
2.7 Adjusting Control Panel Brilliance... 5
2.8 Adjusting GAIN, STC, A/C RAIN
and FTC ............................................ 6
2.9 Tuning the Receiver.......................... 7
2.10 Measuring the Range ........................ 8
2.11 Measuring the Bearing...................... 8
2.12 Menu Operation................................ 9
2.13 Selecting the Display Mode.............11
2.14 The Window Display ...................... 12
2.15 Selecting the Presentation Mode .... 12
2.16 Guard Alarm ................................... 13
2.17 Suppressing Radar Interference...... 14
2.18 Suppressing Noise Interference ...... 15
2.19 Selecting Pulselength...................... 15
2.20 Off Centering the Display............... 15
2.21 Echo Trails...................................... 16
2.22 The Navigation Data Display ......... 16
2.23 Echo Stretch.................................... 17
2.24 Selecting Unit of Measurement
for Range ........................................ 18
2.25 Selecting Bearing Reference .......... 18
2.26 Watchman ....................................... 18
2.27 Erasing the Heading Marker........... 19
2.28 Deselecting Ranges......................... 19
2.29 Displaying Navigation During
Stand-by.......................................... 19
2.30 Outputting Cursor Position to
Navigator ........................................ 20
2.31 Displaying Cursor Position, Range
and Bearing to Cursor..................... 20
2.32 V isual Alarm Indications ................ 20
3. INTERPRETING THE
DISPLAY
3.1 The Radar Wave and Radar Horizon21
3.2 Target Properties and Radar Wave
Reflection ....................................... 21
3.3 Range Resolution............................ 22
3.4 Bearing Resolution ......................... 22
3.5 False Echoes ................................... 22
3.6 Nautical Chart and Radar Picture ... 24
4. MAINTENANCE &
TROUBLESHOOTING
4.1 Safety Information.......................... 25
4.2 Preventative Maintenance............... 26
4.3 Replacing the Fuse.......................... 26
4.4 Troubleshooting.............................. 27
4.5 Self Test .......................................... 28
5. INSTALLATION
5.1 Antenna Unit Installation................ 29
5.2 Display Unit Installation................. 31
5.3 Installation Check List.................... 35
5.4 Initial Adjustment of Picture........... 36
5.5 Displaying the Installation Menus.. 36
5.6 Entering Initial Settings .................. 37
5.7 Relative Bearing Alignment ........... 37
5.8 Sweep Timing................................. 37
5.9 Closing the Installation Menus ....... 38
Declaration of Conformity
v
FOREWORD
Congratulations on your choice of the
FURUNO MODEL 841 MARK-2 Marine
Radar. 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
innovative and dependable marine electronics equipment. This dedication to excellence
is furthered by our extensive global network
of agents and dealers.
Your radar is designed and constructed to
meet the rigorous demands of the marine environment. However, no machine can perform its intended function unless properly
installed and maintained. Please carefully
read and follow the recommended procedures for installation, operation and maintenance.
While this unit can be installed by the purchaser , any purchaser who has doubts about
his or her technical abilities may wish to
have the unit installed by a FURUNO representative or other qualified technician. The
importance of a thorough installation cannot be overemphasized.
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
Your radar has a large variety of functions,
all contained in a remarkably small cabinet.
The main features of the MODEL 841
MARK-2 are:
• Traditional FURUNO reliability and
quality in a compact, lightweight and
low-cost radar.
• Smartly styled, light-weight and compact
radome antenna fits even on small yachts.
• Durable brushless antenna motor.
• High definition 8" LCD raster-scan display.
• On-screen alphanumeric readout of all
operational information.
• Standard features include EBL (Electronic Bearing Line), VRM (Variable
Range Marker), Guard Alarm, Display
Off Center and Echo Trail.
• W atchman feature periodically transmits
the radar to check for radar targets which
may be entering (or exiting) the alarm
zone.
• Operates on 10.2 to 31.2 V DC power
supply and consumes about 40 W.
• Ship’s position in latitude and longitude
(or Loran C T ime Differences), range and
bearing to a waypoint, ship’ s speed, heading and course can be shown in the bottom text area. (Requires a navigation aid
which can output such data in NMEA
0183 format.)
vi
• Zoom feature provided.
SPECIFICATIONS
Antenna Unit
1. Radiator
Printed array
2. Radiator length
54 cm
3. Horizontal beamwidth
3.9°
4. Vertical beamwidth
20°
5. Sidelobe
-20 dB within main lobe
-23 dB outside main lobe
6. Polarization
Horizontal
7. Antenna rotation speed
24 rpm
8. Wind resistance
Relative wind speed 100 kts (51.5 m/s)
Transceiver Module
(contained in radome)
1. Transmitting tube
Magnetron MG5248, E3571 or
MAF1421B
2. Frequency
9410 MHz ±30MHz, P0N (X band)
3. Peak output power
4 kW
4. Pulselength & pulse repetition rate
0.08µs, 2100 Hz (0.25, 0.5, 0.75, 1,
1.5 nm)
0.3µs, 1200 Hz (1.5, 2, 3 nm)
0.8µs, 600 Hz (3, 4, 6, 8, 12, 24, 36
nm)
5. Warm-up time
2:30
6. Modulator
FET switching method
7. I. F.
60 MHz
8. Tuning
Automatic or manual
9. Receiver front end
MIC (Microwave IC)
10. Bandwidth
7 MHz
11. Duplexer
Circulator with diode limiter
Display Unit
1. Indication system
PPI raster scan
2. Display
8-inch diagonal LCD, STN semitransparent, yellow mode
3. Range scales (nm)
Range, Ring Interval: 0.125(0.0625),
0.25(0.125), 0.5(0.125), 0.75(0.25),
1(0.25), 1.5(0.5), 2(0.5), 3(1), 4(1),
6(2), 8(2), 12(3), 16(4), 24(6),
4. Bearing resolution
4°
5. Bearing accuracy
Better than 1°
6. Range discrimination
Better than 25 m
7. Range ring accuracy
0.9% of range in use or 8 m,
whichever is larger
8. Minimum range
Better than 37 m
9. Markers
Heading marker, Bearing scale, Range
ring, VRM, EBL, Waypoint (option),
Tuning indicator, Alarm zone, Cursor
10. Alphanumeric indication
Standard: Electronic Bearing Line
(EBL), Echo Stretch (ES), Rain
Clutter Rejection (FTC), Alarm
(G), Interference Rejection (IR),
36 (6)
vii
Stand-by (ST-BY), Echo Trail Time
(TRAIL), Variable Range Marker
(VRM), Range, Range Ring Interval,
Range and Bearing to Cursor (+), Off
Center (OFF CENTER), Watchman
(WATCHMAN)
With navigation input (option): Course
(CRS), Latitude and longitude, Speed
(SPD), Range and bearing to waypoint
(WP), Cross Track Error (XTE), Date
and time, Water depth, Water
temperature. (This radar has only two
data input ports. To receive data from
more than two equipment install an
mixing device.)
11. Vibration
Vibration freq. Total amplitude
5 to 12.5 Hz ±1.6 mm
12 to 25 Hz ±0.35 mm
25 to 50 Hz ±0.10 mm
12. Ambient temperature
Antenna unit: –20˚C to +70˚C
Display unit: 0˚C to +60˚C
Due to the inherent nature of the LCD
its contrast may be affected under
ambient temperature below 0˚C (32˚F)
or above 50˚C (122˚F).
13. Humidity
Relative humidity 95% or less at
+40˚C
14. Waterproofing
Display unit: IEC Pub no. 529 IPX5
Antenna unit: IEC Pub no. 945 class X
15. Power supply &
power consumption
12 V or 24V(10.2 V to 31.2 V DC),
40 W approx.
16. Protection features
Protection against reverse polarity,
overvoltage, overcurrent, and internal
fault
17. Compass safe distance
Interface NMEA
Input
Own ship’s position : RMA>RMC>GLL
(GLL is available Ver.5 and after.)
Speed : RMA>RMC>VTG>VHW
Heading(True):
HDT>VHW>HDG>VHW>HDM
Heading (Magnetic):
HDM>VHW>HDG>VHW>HDM
Course (True):
RMA>RMC>VTG
Course (Magnetic)
VTG>RMA>RMC
Waypoint (L/L, Range, Bearing):
RMB>BWC>BWR
Loran time difference :
RMA>GLC>GTD
Water depth : DPT>DBK, DBS, DBT
Water temperature : MDA>MTW
Time : ZDA
XTE : RMB>XTE>APB
Output
TLL : On using “HM OFF” key.
RSD : A cycle of four seconds
viii
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EQUIPMENT LIST
Complete Set
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1tinuannetnA850-1700-BSR1
2tinuyalpsiD2M4-311-PDR1
3straperapS00890-30PS144-580-000tes1
4seirosseccA00950-30PF050-264-800tes1
00181-30PC279-680-000
noitallatsnI
5
slairetam
)enotceles(
01181-30PC379-680-000m51:elbaclangis
02181-30PC479-680-000m02:elbaclangis
03181-30PC579-680-000m03:elbaclangis
04181-30PC645-680-000elbaclangiso/w
tes1
Installation Materials (CP03-15xx)
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1tloBxeH403SUS52x01M803-268-0004
2rehsaWtalF403SUS01M131-468-0004
3rehsaWgnirpS403SUS01M162-468-0004
4rotcennoCHX)P5(6971-30038-264-8001
5*elbaclangiS
)enotceleS(
01-27-30S043-574-800
51-27-30S053-574-800
02-27-30S063-574-800
03-27-30S073-574-800
m01
m51
1
m02
m03
m01:elbaclangis
6elbacrewoP0-8419S30316-921-0001m5.3
Spare Parts (SP03-9800)
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1esuFV521CAA5A-OBGF460-945-0002
Accessories (FP03-05900)
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1wercSgnippaT403SUS02x5180-208-0004
.eriwkcihtenohtiwdecalperseriwknipnihtowt;deilppusebyamelbitapmoc16-30S*
ix
Optional Equipment
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1reifitceR26-RP484-310-000
2rezzuBlanretxE631-30PO344-680-0001
3)1(tekcarBgnitnuoM29-30PO070-544-0001taobliasroF
1
584-310-000CAV011
684-310-000CAV022
784-310-000
CAV001
CAV032
x
CONFIGURATION
MODEL 841 MARK-2
Antenna Unit
NAV
IEC 1162*
Video Sounder
IEC 1162*
Fluxgate Heading
Sensor C-2000
Gyro
Gyro Converter
AD-100
*Equivalent to NMEA0183
Option
(In/Out)
(In)
5A
10.2~31.2VDC
Remote Display
FMD-811
External Alarm
Buzzer OP03-136
Rectifier
PR-62
115/230VAC
xi
1. PRINCIPLE OF OPERATION
1.1 What is Radar?
The term "RADAR" is an acronym meaning RAdio Detection And Ranging. Although the basic principles of radar were
developed during World War II, primarily
by scientists in Great Britain and the United
States, the use of echoes as an aid to navigation is not a new development.
1.2 How Ships Determined Position Before Radar
Before the invention of radar , when running
in fog near a rugged shoreline, ships would
sound a short blast on their whistles, fire a
shot, or strike a bell. The time between the
origination of the sound and the returning
of the echo indicated how far the ship was
from the cliffs or the shore. The direction
from which the echo was heard indicated
the relative bearing of the shore.
1.3 How Radar Determines
1.4 How Radar Determines Bearing
The bearing to a target found by the radar is
determined by the direction in which the
radar scanner antenna is pointing when it
emits an electronic pulse and then receives
a returning echo. Each time the scanner rotates pulses are transmitted in the full 360
degree circle, each pulse at a slightly different bearing from the previous one. Therefore, if one knows the direction in which the
signal is sent out, one knows the direction
from which the echo must return.
1.5 Radar Wave Speed and Antenna Rotation Speed
Note that the speed of the radar waves out
to the target and back again as echoes is extremely fast compared to the speed of rotation of the antenna. By the time radar echoes
have returned to the scanner, the amount of
scanner rotation after initial transmission of
the radar pulse is extremely small.
Range
Radar determines the distance to the target
by calculating the time difference between
the transmission of a radar signal and the
reception of the reflected echo. It is a known
fact that radar waves travel at a nearly constant speed of 162,000 nautical miles per
second. Therefore the time required for a
transmitted signal to travel to the target and
return as an echo to the source is a measure
of the distance to the target. Note that the
echo makes a complete round trip, but only
half the time of travel is needed to determine the one-way distance to the target. This
radar automatically takes this into account
in making the range calculation.
1.6 The Radar Display
The range and bearing of a target is displayed
on what is called a Plan Position Indicator
(PPI). This display is essentially a polar diagram, with the transmitting ship’s position
at the center. Images of target echoes are
received and displayed at their relative bearings, and at their distance from the PPI center.
With a continuous display of the images of
targets, the motion of the transmitting ship
is also displayed.
1
Targets
Heading line
Range and bearing
A
D
A
of a target, relative
to own ship, are
D
readable on the PPI.
B
C
Own ship
(radar)
(A) Bird's eye view of situation
Figure 1-1 How radar works
B
C
Own ship
in center
(B) Radar picture of (A)
2
2. OPERATION
2.1 Control Description
Cursor pad
Shift cursor, VRM
and EBL; select
items and options
on menu.
Registers selection
on menus.
Press to adjust gain,
A/C RAIN, STC
and FTC.
Adjusts display
tone.
Turns the EBL
on/off.
Plots targets' trails.
Sets guard
zone area.
Selects display mode;
erases heading error
indication.
ENT MENU
ECHO
RANGE
TONE BRILL
EBL
TRAIL
GUARD
DISP
MODE
HM
OFF
VRM
RINGS
OFF
CENTER
ST-BY
TX
Opens/closes menus.
Erases heading marker;
selects cursor data (Lat/Long, R/B);
outputs cursor position.
Selects radar range.
Adjusts display brilliance.
Turns the VRM on/off.
Turns the range
rings on/off.
Off centers
the display.
Sets radar in stand-by;
transmits radar pulse.
POWER
Figure 2-1 Control panel
Turns power on/off.
3
2.2 Display Indications and Markers
Range
Range ring interval
Presentation mode
Off center
Pulsewidth
Heading marker
Guard zone
area
Cursor
0.5
CU
OFF
CENTER
SP
1.5
HDG 326.8°
NM
Heading (requires
heading data)
TRAIL AUTO
0:00
15S
G (IN)
FTC1
ES
Echo trail, AUTO tuning
Echo trail elapsed time,
echo trail time, tuning indicator
Guard zone
IR
Fast Time Constant
(rain clutter suppressor)
Echo stretch
Interference rejector
Range ring
EBL
VRM EBL + CURSOR
0.675
NM
VRM
range
220.9°
R
0.646NM 308.7°
EBL
bearing
Figure 2-2 Display indications
2.3 Turning the Radar On and Off
Turning the radar on
Press the [POWER] key to turn the radar on
or off. The control panel lights and a timer
displays the time remaining for warm up of
the magnetron (the device which produces
radar pulses), counting down from 2:30 to
0:01.
VRM
Range and bearing to cursor
or cursor position in latitude
and longitude may be displayed
}
by pressing the [HM OFF] key.
Cursor
range
R
Cursor
bearing
CAUTION
The radar antenna emits high frequency
radio radiation which can be harmful,
particularly to your eyes. Never look
directly at the antenna from a distance of
less than two feet when the radar is in
operation. Always make sure no one is near
the antenna before turning on the radar.
Note: When the power is reapplied within a
certain amount of time and circuits remain
charged, the warmup process is skipped—you
can transmit immediately.
4
Note: When the heading signal is lost, the HDG
readout at the top of the screen shows ***.*.
This warning stays on when the heading signal is restored to warn the operator that the
readout may be unrealiable. The warning may
be erased by pressing the [DISP MODE] key,
2.4 Transmitting
After the power is turned on and the magnetron has warmed up, ST-BY (Stand-By)
appears at the screen center . This means the
radar is now fully operational. In stand-by
the radar is available for use at anytime—
but no radar waves are being transmitted.
2.6 Adjusting LCD Backlighting and Display Tone
The [BRILL] key adjusts the LCD backlighting in eight levels, including off. The
[TONE] key adjusts the tone (contrast) of
the display in 32 levels, including off.
Press the [ST -BY TX] key to transmit. When
transmitting, any echoes from targets appear
on the display . This radar displays echoes in
four tones of gray according to echo strength.
When you won’t be using the radar for an
extended period but want to keep it in a state
of readiness, press the [ST-BY TX] key to
set the radar in stand-by.
2.5 Selecting the Range
The range selected automatically determines
the range ring interval, the number of range
rings, pulselength and pulse repetition rate,
for optimal detection capability in short to
long ranges.
Procedure
Procedure
1) Press the [BRILL] key (or [TONE] key).
The display shown in Figure 2-3 appears.
BRILL
UP
Tone
setting
TONE
DOWN
BRILL
19 7
DOWN
<MENU TO EXIT>
TONE
UP
Item selected
for adjustment
LCD brilliance
setting
Figure 2-3 Display for adjustment of
brilliance and tone
2) Press the [BRILL] key (or [TONE] key)
to set level. For fine adjustment, press
cursor pad at 12o'clock/6 o'clock for brilliance and 3o'clock/9o'clock for tone.
Press the [– RANGE +] key . The range and
range ring interval appear at the top left corner on the display.
Tips for selecting the range
• When navigating in or around crowded
harbors, select a short range to watch for
possible collision situations.
• If you select a lower range while on open
water , increase the range occasionally to
watch for vessels that may be heading
your way.
2.7 Adjusting Control Panel Brilliance
Procedure
1) Press the [MENU] key.
2) Press the cursor pad to select Backlight/
Brilliance and press the [ENT] key.
3) Press the cursor pad to select Panel.
4) Press the cursor pad to select brilliance
level; 4 is the highest.
5) Press the [ENT] key followed by the
[MENU] key.
5
2.8 Adjusting GAIN, STC, A/C RAIN and FTC
General procedure
The [ECHO] key enables adjustment of the
gain, STC, A/C RAIN and FTC.
1) Press the [ECHO] key . The following display appears.
AUTO 1 2 3
[
GAIN
STC
A/C RAIN 00
FTC 0 1 2
◆
◆
[
MAN
AUTO 1 2 3
MAN
12
ECHO KEY
TO EXIT
Figure 2-4 Display for adjustment of
GAIN, STC, A/C RAIN and FTC
2) Press the cursor pad to select item to adjust. Current selection is circumscribed
by dashed rectangle.
3) Press [ENT].
3) Press the cursor pad to set level.
Item selected
for adjustment
Current
level
How to adjust STC (suppressing sea
clutter)
Echoes from waves can be troublesome,
covering the central part of the display with
random signals known as sea clutter. The
higher the waves, and the higher the scanner above the water, the further the clutter
will extend. Sea clutter appears on the display as many small echoes which might affect radar performance. (See the left-hand
figure in Figure 2-5).
The STC reduces the amplification of echoes at short ranges (where clutter is the greatest) and progressively increases
amplification as the range increases, so amplification will be normal at those ranges
where there is no sea clutter. The control is
effective up to about 4 miles.
STC can be adjusted automatically or manually . For manual adjustment, first adjust the
gain and then transmit on short range. Adjust the STC level such that the clutter is
broken up into small dots, and small targets
become distinguishable. If the setting is set
too low, tar gets will be hidden in the clutter ,
while if it is set too high, both sea clutter
and targets will disappear from the display.
In most cases adjust so clutter has disappeared to leeward, but a little is still visible
windward.
4) Press the [ECHO] key to finish.
How to adjust the gain (sensitivity)
The gain works in precisely the same manner as the volume control of a broadcast receiver, amplifying the signals received.
You can adjust the gain automatically or
manually . For manual adjustment, adjust the
sensitivity on the highest range—the background noise is clearer on that range. The
proper setting is such that the background
noise is just visible on the screen. If you set
up for too little gain, weak echoes may be
missed. On the contrary excessive gain
yields too much background noise; strong
targets may be missed because of the poor
contrast between desired echoes and the
background noise on the display.
6
If there is no clutter visible on the display,
turn off the circuit.
Sea clutter at
display center
STC adjusted;
sea clutter suppressed.
Figure 2-5 Effect of STC
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