Furuno 1761 MARK-3 User manual

C
9-52, Ashihara-cho,
Nishinomiya, Japan
Telephone: [phone]
Telefax: 0798-65-4200
Your Local Agent/Dealer
All ri
g
hts reserved.
PUB. No. OME-34810
MODEL 1761 MARK-3
(
YOSH
)
FIRST EDITION : AUG. 1998
D : JUL. 10, 2001
Printed in Japan

i
SAFETY INSTRUCTIONS
DANGER
Radio Frequency Radiation Hazard
The radar antenna emits electromagnetic radio frequency (RF) energy which can be
harmful, particularly to your eyes. Never look directly into the antenna aperture from a
close distance while the radar is in operation or expose yourself to the transmitting
antenna at a close distance.
Distances at which RF radiation levels of 100 and 10 W/m
2
exist are given in the table
below.
Note: If the antenna unit is installed at a close distance in front of the wheel house,
your administration may require halt of transmission within a certain sector of antenna
revolution. This is possible—Ask your FURUNO representative or dealer to provide
this feature.
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.
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ii
DANGER
Before turning on the radar
make sure no one is near the
scanner unit.
Prevent the potential risk of
someone begin struck by the
rotating antenna and exposure
to RF radiation hazard.
WARNING
Do not open the equipment.
Improper handling can result in electrical
shock. Only qualified personnel shold
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 equip-
ment is emitting smoke or fire.
Continued use of the equipment can
cause fire or electrical shock.
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.
WARNING
Use the proper fuse.
Fuse rating is shown in the chapter 5.
Use of a wrong fuse can result in equipment
damage
Do not operate the equipment with wet
hands.
Electrical shock can result.
Do not use the equipment for other than
its intended purpose.
Use of the equipment as a stepping stool,
for example, can result in personal injury
or equipment damage.
No one navigation device should ever be
solely replied upon for the navigation of
a vessel.
Always confirm position against all available
aids to navigation, for safety of vessel and
crew.
CAUTION
Two warning labels are attached to the display
unit and scanner unit. Do not remove these labels.
If labels are peeling off or are illegible, contact
a FURUNO agent or dealer.
WARNING
To avoid electrical shock, do not
remove cover. No user-serviceable
parts inside.
<Display Unit>
Name: Warning Label (1)
Type: 86-003-1011-0
Code no.: 100-236-230
WARNING
Radiation hazard. Only qualified
personnel should work inside scanner.
Confirm that TX has stopped before
opening scanner.
<Scanner Unit>
Name: Radiation Warning
Label
Type: 03-142-3201-0
Code no.: 100-266-890

iii
Congratulations on your choice of the
FURUNOMODEL1761MARK-3MarineRa-
dar. We are confident you will see why the
FURUNO name has become synonymous
with quality and reliability.
For over 50 years FURUNO Electric Com-
pany has enjoyed an enviable reputation for
innovativeand dependable marineelectron-
icsequipment.Thisdedication to excellence
is furthered by our extensive global network
of agents and dealers.
Your radar is designed and constructed to
meettherigorousdemandsofthe marine en-
vironment. However, no machine can per-
form its intended function unless properly
installed and maintained. Please carefully
read and follow the recommended proce-
dures for installation, operation and mainte-
nance.
While this unit can be installed by the pur-
chaser, any purchaser who hasdoubtsabout
hisorher technical abilities may wishtohave
the unit installed by a FURUNO representa-
tive or other qualified technician. The impor-
tance of a through installation can not 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 1761
MARK-3 are:
¡Traditional FURUNO reliability and qual-
ity in a compact, lightweight and low-cost
radar.
¡Durable brushless antenna motor.
¡On-screenalphanumericreadoutofallop-
erational information.
¡StandardfeaturesincludeEBL(Electronic
Bearing Line), VRM (Variable Range
Marker), Guard Alarm, Display Off Cen-
ter, and Echo Trail.
¡Watchman feature periodically transmits
the radar to check for radar targets which
may be entering the alarm zone.
¡Ship’s position in latitude and longitude,
range and bearing to a waypoint, and
ship’s speed/heading/course can be
shown in the bottom text area. (Requires
a navigation aid which can output such
data in IEC 61162 format.)
¡Zoom feature provided.
FOREWORD

iv
TABLE OF CONTENTS
FOREWORD.............................. iii
MENU TREE ............................... v
TABLE OF CONTENTS BY
INDICATION, MARKER............. vi
SYSTEM CONFIGURATION..... vii
1. PRINCIPLE OF OPERATION
1.1 What is Radar? .............................. 1-1
1.2 How Ships Determined Position Before
Radar ............................................. 1-1
1.3 How Radar Determines Range ...... 1-1
1.4 How Radar Determines Bearing .... 1-1
1.5 Radar Wave Speed and Antenna
Rotation Speed .............................. 1-1
1.6 The Radar Display ......................... 1-1
2. OPERATION
2.1 Control Description......................... 2-1
2.2 Turning the Radar On/Off............... 2-2
2.3 Transmitting.................................... 2-2
2.4 Stand-by......................................... 2-2
2.5 Selecting the Range....................... 2-2
2.6 Adjusting Picture Brilliance............. 2-2
2.7 Adjusting Receiver Sensitivity ........ 2-2
2.8 Adjusting the A/C SEA Control
(reducing sea clutter)..................... 2-3
2.9 Adjusting the A/C RAIN Control
(reducing rain clutter)..................... 2-4
2.10 Adjusting FTC............................... 2-4
2.11 Turning the Radar Receiver ......... 2-4
2.12 Erasing the Heading Marker ........ 2-4
2.13 Select the Cursor Data Display.... 2-5
2.14 Turning the Range Ring On/Off ... 2-5
2.15 Measuring the Range................... 2-5
2.16 Measuring the Bearing................. 2-5
2.17 Shifting and Zooming the Display ......
..................................................... 2-6
2.18 Menu Operation ........................... 2-7
2.19 Echo Stretch................................. 2-8
2.20 Suppressing Radar Interference .. 2-8
2.21 Adjusting Control Panel Brilliance ......
..................................................... 2-8
2.22 Selecting Ranges ......................... 2-9
2.23 EBL/Cursor Bearing Reference ... 2-9
2.24 Guard Alarm ................................. 2-9
2.25 Watchman .................................. 2-10
2.26 Plotting ........................................2-11
2.27 Navigation Data Display..............2-11
3. FALSE ECHOES
3.1 Multiple Echoes.............................. 3-1
3.2 Side-lobe Echoes ........................... 3-1
3.3 Indirect Echoes .............................. 3-2
3.4 Blind and Shadow Sectors............. 3-2
3.5 SART (Search and Rescue
Transponder) ................................. 3-3
4. MAINTENANCE & TROUBLE-
SHOOTING
4.1 Preventive Maintenance ................ 4-1
4.2 Replacing the Fuse ........................ 4-1
4.3 Troubleshooting.............................. 4-2
4.4 Life Expectancy of Magnetron ....... 4-3
SPECIFICATIONS ................ SP-1
INDEX .....................................IN-1

v
MENU TREE
1. ECHO STRETCH (ON, OFF)
2. I. REJECT (OFF, ON)
3. PANEL DIMMER (0, 1, 2, 3, 4)
4. PLOT INTVL (CONT, 30S, 1M, 3M, 6M)
5. PLOT BRILL (LOW,
@ HIGH)
6. RANGE (NM) set with (RING)
(1/4, 1/2, 3/4, 1, 1.5, 2, 3, 4, 6, 8, 12, 16, 24, 48)
7. WATCHMAN (OFF, 5M, 10M, 20M)
8. NAV DATA (ON, OFF)
9. EBL/+CURSOR (TRUE, REL)
MENU KEY

vi
TABLE OF CONTENTS BY
INDICATION, MARKER
MAG 115.0¡
SHIFT
12 NM
3.0 NM
PLOT 3M
FTC
IR
GUARD
VRM
2.62 NM
315.1 R
¡
9.05 NM
EBL
45.6 R
¡
18:25 ES
*
WATCHMAN
Tuning indicator (P.2-11)
Echo stretch (P.2-8)
Guard alarm (P.3-4)
FTC (P.2-4)
EBL (P.2-6)
Range ring (P.2-3, 2-5)
Interference rejector (P.2-8)
VRM range (P.2-5)
Cursor data(P.2-5)
Bearing /Range or
Latitude/Longitude
EBL1 bearing (P.2-6)
Guard zone (P.2-9)
Cursor (P.2-5, 6)
Shift (or Zoom) (P.2-6)
Range ring interval (P.2-2)
Range (P.2-2)
MAG (or GYRO) BEARING (option)
Heading marker (P.2-4)
Plotting (P.2-11)
Elapsed time (P.2-11)
Plotting interval (P.2-11)
Watchman (P.2-10)

vii
SYSTEM CONFIGURATION
*Equivalent to NMEA 0183
Option
RDP-099
Navigation
device IEC 61162* (In/Out)
Gyro-
compass Gyro Converter
AD-100
12/24/32 VDC
Rectifier
RU-3423
115/230 VAC
External Alarm
Buzzer OP03-21
Scanner Unit
XN10A-RSB-0070-065
Display Unit
12 VDC: 10A
24/32 VDC: 5A
Intergrated Heading
Sensor PG-1000

1-1
1.1 What is Radar?
The term “RADAR” is an acronym meaning
RAdio Detection And Ranging. Although the
basicprinciplesof radar were developeddur-
ing World War II, echoes as an aid to naviga-
tion 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
whichthe echo washeard indicated therela-
tive bearing of the shore.
1.3 How Radar Determines
Range
Radar determines the distance to the target
bycalculatingthetimedifferencebetweenthe
transmissionof a radarsignal and therecep-
tion 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 dis-
tanceto the target. Notethatthe 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 automati-
cally takes this into account in making the
range calculation.
1. PRINCIPLE OF OPERATION
1.4 How Radar Determines
Bearing
The bearing to a target found by the radar is
determined by the direction in which the ra-
darscannerantennais pointing when it emits
an electronic pulse and then receives a re-
turning echo. Each time the scanner rotates
pulses are transmitted in the full 360 degree
circle, each pulse at a slightly different bear-
ing from the previous one. Therefore, if one
knowsthedirectionin which the signal issent
out, one knows the direction from which the
echo must return.
1.5 Radar Wave Speed and
Scanner 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 ro-
tation of the scanner. By the time radar ech-
oeshavereturnedtothescanner, the amount
of scanner rotation after initial transmission
of the radar pulse is extremely small.
1.6 The Radar Display
Therangeandbearingof a target is displayed
on what is called a Plan Position Indicator
(PPI). This display is essentially a polar dia-
gram, with the transmitting ship’s position at
the center. Images of target echoes are re-
ceived and displayed at their relative bear-
ings,andattheir distance fromthePPIcenter.
With a continuous display of the images of
targets, the motion of the transmitting ship is
also displayed.

1-2
A
BC
D
Own ship
(radar)
D
A
BC
Heading marker
Targets
Own ship
in center
(A) Bird's eye view of situation (B) Radar picture of (A)
Range and bearing
of a target, relative
to own ship, are
readable on the PPI.
Figure 1-1 How radar works

2-1
2. OPERATION
2.1 Control Description
POWER
BRILL
SHIFT
ZOOM
RING
EBL VRM
MENU
RANGE
OFF
ECONOMY
STBY
T X
GAIN
PUSH/HM OFF
A/C SEA
A/C RAIN
Turns power on.
Press together with [STBY/TX] key
to turn power off.
Alternates between stand-by and
transmit.
Adjusts the brightness of the screen.
Selects radar range.
The "+" and "-" touchpads select a
higher and lower range, respectively.
Selets items during the menu display.
Turns the Electronic Bearing
Line (EBL) on and off.
Turns on and off the guard zone alarm.
(Control) Adjusts sensitivity of radar
receiver.
(Switch) 1. Temporarily erases heading
marker.
2. Change + cursor data from
R/B to L/L and vice versa.
(Control) Reduces sea clutter caused
by waves.
(Switch) Turns on/off the radar
target plotting
(Control) Reduces rain clutters.
(Switch) Suppresses heavy
precipitation.
Turns the fixed range rings on and off.
Turns the Variable Range Marker
(VRM) on and off.
Trackball
(1) Shifts cursor, EBL and VRM.
(2) Sets guard zone.
(3) Selects items and options on
menu.
(4) Shifts origin of EBL and VRM.
PUSH/PLOT
PUSH/FTC
GUARD
Turns the menu display on and off.
Lights (in green) to show the
radar is in the "echonomy
(stand-by)" mode.
Shifts the display; turns the zoom
function on, and restores normal
picture, in that order.
Figure 2-1 Control panel

2-2
2.2 Turning the Radar On/Off
After confirming there are no crew near the
scanner unit, press the [POWER] key to turn
on the power.
The front panel will light up. The magnetron
takes about two minutes and thirty seconds
to warm up before the radar can be oper-
ated. The time remaining for warm up of the
magnetron appears at the center of the dis-
play, counting down from 2:29 to 0:01.
To turnofftheradar, press the[POWER] and
[TX] key together.
2.3 Transmitting
After the power is turned on and the magne-
tron has warmed up, the message “ST-BY”
(Stand-By) appears at the center of the dis-
play, showing the radar is ready to transmit.
However,notargetswillappearonthescreen
until the radar is transmitting by pressing the
[TX] key (TX is short for “transmit). In stand-
by the radar is available for use at anytime -
but no radar waves are being transmit.
2.4 Stand-by
When you won’t be using the radar for an
extended period, but you want to keep it in a
state of readiness, place it in stand-by by
pressing the [TX] key. The display shows
“STBY,” (default setting) or goes into the
economy mode. (You can select stand-by
condition on the menu. )
Economy mode
The CRT can be set to automatically turn it-
self off when in stand-by, to reduce power
consumption. This feature is called the
“economy mode”. When the economy mode
is on, the “ECONOMY” indication under the
[TX] key lights.
2.5 Selecting the Range
Therangeselectedautomaticallydetermines
the fixed range ring interval, the number of
fixedrangerings,pulselength, and pulse rep-
etition rate, for optimal detection in short to
long ranges. The range and ring interval ap-
pear at the top left corner of the display.
Selecting the range
Press the [- RANGE +] key. The range and
range ring interval appear at the top left cor-
ner on the display.
Tips for selecting the range
• When navigating in or around crowded
harbors, select a short range to watch for
possible collision situation.
• If you select a lower range while on open
water, increase the range occasionally to
watch for vessels that may be heading
your way.
2.6 Adjusting Picture
Brilliance
The [BRILL] key adjusts the brilliance of the
radar picture in eight levels.
Press the [BRILL] key to set the brilliance
level.
2.7 Adjusting Receiver
Sensitivity
The [GAIN] control adjusts the sensitivity of
the receiver. It works in precisely the same
manneras the volumecontrol of abroadcast
receiver, amplifying the signals received.
The proper setting is such that the back-
ground noise is just visible on the screen. If
you set up noise is just visible on the screen.
If you set up for too little sensitivity, weak
echoes may be missed. On the other hand
excessive sensitivity yields too much back-
ground noise; strong targets may be missed
becauseofthepoor contrast betweendesired

2-3
echoesand the background noiseonthe dis-
play.
To adjustreceiversensitivity, transmit on long
range,andadjust the [GAIN] controlsoback-
ground noise is just visible on the screen.
Tips on adjusting GAIN
• In certain circumstances it may be useful
to reduce the gain slightly to improve
range resolution, clear up the picture, or
reduce clutter caused by rain or snow.
• Range resolution is a measure of the ca-
pability of a radar to display as separate
pipstheechoesreceived from two targets
which are on the same bearing, and are
close together radially. With reduction in
thegainsetting,the echoes may be made
toappearas separate pips onthedisplay.
• When sailing or cruising in crowded re-
gionsaslightreductionin gain often helps
to clear up the picture. This should be
done carefully, otherwise weak targets
may be missed.
• Echoesfromshipsinsideasquallorstorm
may be obscured if the gain is at its nor-
mal setting, since the clutter may have
masked, but not completely, echoes from
the targets.
Note: In all cases, return the gain to its origi-
nal position after any temporary reduction is
no longer required.
2.8 Adjusting the A/C SEA
Control
(reducing sea clutter)
Echoesfromwavescanbe troublesome, cov-
ering the central part of the display with ran-
dom signals known as “sea clutter”. The
higherthewaves,and the higher the antenna
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 2-2.) When sea clutter masks the
picture, adjust theA/C SEAcontrol to reduce
the clutter.
How the A/C SEA control works
The [A/C SEA] control reduces the amplifi-
cation of echoes at short ranges (where clut-
ter is the greatest) and progressively
increases amplification as the range in-
creases, so amplification will be normal at
those ranges where there is no sea clutter.
Adjusting the A/C SEA control
The proper setting of theA/C SEAshould be
such that the clutter is broken up into small
dots, and small targets become distinguish-
able.
If the control is set too low, targets 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 the
control until clutter has disappeared to lee-
ward, but a little is still visible windward.
1. Confirmthat the sensitivityisproperly ad-
justed, and then transmit on short range.
2. Adjust the [A/C SEA] control so small tar-
gets are distinguishable but some clutter
remains on the display.
Sea clutter at
display center A/C SEA control adjusted; sea clutter suppressed.
Figure 2-2 How to adjust the A/C SEA
control
Tip for adjusting the A/C SEA
A common mistake is to over-adjust the cir-
cuit so all the removed. As an example set
up for maximum A/C SEA. You will see how
the center of the display becomes dark. This
dark zone can be dangerous (targets may
be missed), especially if the sensitivity is not
properly adjusted. Always leave a little clut-
ter visible on the display to be sure weak
echoes will not be suppressed. If there is no
clutter visible on the display, turn off the cir-
cuit.

2-4
2.9 Adjusting the A/C RAIN
Control
(reducing rain clutter)
The vertical beamwidth of the antenna is de-
signed to see surface targets even when the
ship is rolling. However, by this design the
unit will also detect rain clutter (rain, snow,
hail, etc.) in the same manner as normal tar-
gets.Figure2-3shows the appearanceofrain
clutter on the display.
Adjusting A/C RAIN
When rain clutter masks echoes, adjust the
[A/C RAIN] control. This control splits up
these unwanted echoes into a speckled pat-
tern, marking recognition of solid targets
easier.
Appearance of
rain clutter A/C RAIN control adjusted; rain clutter suppressed.
Figure 2-3 Effect of A/C RAIN
Note: Inaddition to reducingclutter, the[A/C
RAIN] control can be used in fine weather to
clarifythepicturewhennavigatinginconfined
waters.However,withthecircuitactivatedthe
receiver is less sensitive. Therefore, turn off
the circuit when its function is not required.
2.10 Adjusting FTC
To suppress rain clutter from heavy storms
orscatteredrain clutter,press the [A/C RAIN]
control ([FTC] switch). The FTC circuit splits
up these unwanted echoes into a speckled
pattern, marking recognition of solid targets
easier. “FTC” appears at the top right-hand
cornerofthedisplaywhenthecircuitisturned
on.
Note: Inaddition to reducingclutter, theFTC
can be used in fine weather to clarify the pic-
ture when navigating in confined waters.
However, with the circuit activated the re-
ceiverislesssensitive.Therefore,turnoffthe
circuit when its function is not required.
2.11 Tuning the Radar Receiver
The radar receiver is tuned automatically
each time you turn on the power, thus there
is no front panel control for adjustment of the
receiver. To show the automatic tuning cir-
cuit is working, a tuning bar displays tuning
condition.
2.12 Erasing the Heading
Marker
The heading marker may occasionally mask
a target. To view the target, you can tempo-
rarily erase the heading marker by pressing
andholding downthe [GAIN (HMOFF)] con-
trol. Release the control to re-display the
markers.
Heading
marker
Figure 2-4 Heading marker

2-5
2.13 Select the Cursor Data
Display
When connecting with NAV (IEC61162 for-
mat) and gyro converter (IEC61162 or AD-
10 format), this radar can show the cursor
position by Latitude/longitude at bottom of
screen.
Each time pressing [HM OFF] key, the data
will change from Range/Bearing to Latitude/
longitude and vice versa.
Whenthecursorpositionis displayed by Lati-
tude/Longitude, pressing the [HM OFF] key
outputs L/L data of the cursor position (TLL)
to the plotter. Then Range/Bearing are dis-
played instead of L/L.
2.14 Turning the Range Ring
On/Off
Whenrange rings obscures atarget,you can
erase them by pressing the [RING] key.
2.15 Measuring the Range
You can measure the range to a target three
ways: by the range rings, by the cursor, and
by the VRM (Variable Range Marker).
Measuring range by range rings
Count the number of rings between the cen-
ter of the display and the target. Check the
range ring interval and judge the distance of
the echo from the inner edge of the nearest
ring.
To turn the rings on or off, press the [RING]
key.
Measuring range by cursor
Operator the trackball to place the cursor in-
tersection on the inside edge of the target
echo. The range to the target, as well as the
bearing,appearsat the bottomofthedisplay.
Measuring by VRM
1. Press the [VRM] key to display a VRM.
(The VRM is the dotted ring.)
2. Place the VRM on the inside edge of the
target by operating the trackball.
3. Pressthe [VRM] keyagain to fixthe VRM
to the position.
4. Checktherange readout tofindtherange
to the target. To erase the VRM, press
and hold down the [VRM] key for about
three seconds.
VRM
6.0 NM
2.0
Range
Range ring
interval
Target
Cursor
Cursor range
315.1°R
4.0 NM VRM
4.0 NM VRM
range
Figure 2-5 Measuring Range by the Cursor
and the VRM
Unit of range measurement
You can display the range readouts of the
VRM and the cursor in nautical miles or kilo-
meters. This is done at installation.
2.16 Measuring the Bearing
There are two ways to measure the bearing
to a target: by the cursor, and by the EBL
(Electronic Bearing Range).
Measuring bearing by cursor
Operatethe trackball tobisectthe target with
the cursor intersection. The bearing to the
target appears at the bottom of the display.
Measuring by EBL
1. Press the [EBL] key to display an EBL.
(The EBL is the dotted line.)

2-6
2. Position the EBL so it bisects the target
by operating the trackball.
3. Press the [EBL] key again to fix the EBL
to the position.
4. Check the bearing readout to find the
bearing of the target. To erase the EBL,
press and hold down the [EBL] key for
about three seconds.
6.0 NM
2.0
EBL1 bearing
R: Relative Bearing
T: True Bearing*
40.0° R
EBL
EBL
Target
Cursor
Cursor Bearing
R: Relative Bearing
T: True Bearing*
41.5°R
4.0 NM
MAG115.0°
MAG (or GYRO) BEARING*
*: Heading sensor
(or gyrocompass)
connection required
Figure 2-6 Measuring Bearing by the EBL
and Cursor
The bearing measured by the cursor or the
EBLcan be displayed inrelativeor true bear-
ings (heading sensor or gyrocompass con-
nection required). Relative bearings are
relative to the bow of the vessel, and true
bearings are relative to the True North. The
indication “MAG” (or GYRO”) and the head-
ing sensor (or gyrocompass) bearing (your
ship’s bearing) appear at the top of the
screen.
Note that the bearing to the cursor always
varies with trackball operation. The EBLand
itsindication,however,areautomaticallyfixed
whenthe [EBL] key ispressedor 10 seconds
elapses without trackball operation.
Tips on measuring bearing
• Bearingmeasurementsof smaller targets
pips are more accurate; the center of
larger target pips is not as easily identi-
fied.
• Bearings of stationary or slower moving
targets are more accurate than bearings
of faster moving targets.
• To minimize bearing errors keep echoes
in the outer half of the picture by chang-
ing the range scale; angular difference
becomes difficult to resolve as a target
approaches the center of the display.
2.17 Shifting and Zooming the
Display
The [SHIFT/ZOOM] key has two functions:
display shifting and display zoom. Each time
the key is pressed the function changes in
the following sequence.
Normal Shift Zoom
Figure 2-7 SHIFT/ZOOM key sequence
Shift
Theown ship’sposition can be shiftedto any
position within thecurrent range. The primary
advantage of the shifted display is that for
anyrangesetting,theviewahead of your own
ship can be extended without changing the
range.
Place the cursor on area you wish to shift to
thescreencenter and then pressthe[SHIFT/
ZOOM]key. The indication “SHIFT”appears.
To restore normal operation press the key
twice.
Note: If the cursor is not within the current
range when the key is pressed, an audible
beep sounds and the outermost range ring
blinks twice , even if the range rings are
off.
Zoom
The zoom feature allows you to double the
area between own ship and an arbitrary lo-
cation, to take a closer look at an area of in-
terest without changing the range.
1. Operate the trackball to place the cursor
on the target you want or area you want
to zoom.

2-7
2. Press the [SHIFT/ZOOM] key. The indi-
cation “ZOOM” appears and brinks.
3. To turn off the zoom, press the [SHIFT/
ZOOM] key again, or change the range.
Cursor
Place cursor
where desired.
Display magnifies.
Press the
[SHIFT/ZOOM]
key.
Display shifts.
(Normal display)
SHIFT ZOOM
Press the
[SHIFT/ZOOM] key.
Press the
[SHIFT/ZOOM] key.
Figure 2-8 Shifting and zooming the display
2.18 Menu Operation
Themenu, consisting of9 items, mostlycon-
tains less-often used functions which once
preset do not require regular adjustment. To
open or close the menu, press the [MENU]
key. You can select menus by using the
trackball, then select item with the [RANGE]
key.
Note: Current selections shown in reverse
video.
SEL MENU BY TRKBALL:
ITEMS WITH RANGE KEY
¡ECHO STRETCH
2 I. REJECT
3 PANEL DIMMER
4 PLOT INTVL
5 PLOT BRILL
6 RANGE (NM)
SET WITH
(RING)
7 WATCHMAN
8 NAV DATA
9 EBL/+CURSOR
MENU
ON OFF
OFFON
0 1 2 34
CONT 30S 1M 3M 6M
LOW HIGH
1/4 1/2 3/4 11.5 2 3
46 8 12 16 24 36 48
OFF 5M 10M 20M
ON OFF
TRUE REL
Figure 2-9 MENU Display
Table 2-1 Menu Description
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2-8
2.19 Echo Stretch
Normally, thereflected echoes fromlongdis-
tancetargetsappearonthe screen as weaker
andsmallerblips even through theyarecom-
pensatedbythe radar’sinternalcircuitry.The
Echo Stretch function magnifies these small
blips.
1. Press the [MENU] key to open the menu.
2. Operate the trackball to select “1. ECHO
STRETCH”.
3. Press the [RANGE] key to select “ON”.
The indication “ES” appears at the upper
right-handside of thescreen and theechoes
are doubled lengthwise.
To turn off the echo stretch, select “OFF” on
the MENU display.
Note 1: This function magnifies not only tar-
gets but also sea clutter and radar interfer-
ence are properly adjusted before activating
the echo stretch.
Note 2: This function is inactivate on short
ranges, that is 0.25 to 1 nautical miles. “ES”
appears in reverse video when the echo
stretch is turned on in those ranges.
2.20 Suppressing Radar
Interference
Radarinterference may occurwhennear an-
other shipborne radar operating in the same
frequency band as your radar. Its on-screen
appearance is many bright dots either scat-
tered at random or in the form of dotted lines
extending from the center (or the edge) to
the edge (or the center) of the display. Fig-
ure 2-11 illustrates interference in the form
of curved spokes, Interference effects are
distinguishablefromnormal echoes because
theydo not appearinthe same placeon suc-
cessive rotations of the scanner.
Figure 2-10 Radar interference
1. Press the [MENU] key to open the menu.
2. Operate the trackball to select “2. I. RE-
JECT”.
3. Press the [RANGE] key to select “ON”.
(Factory setting is ON.)
Theindication“IR”appearsattheupperright-
hand side of the screen. Press the [MENU]
key again to erase the menu display.
2.21 Adjusting Control Panel
Brilliance
Adjusts the backlighting of the front panel in
five steps.
1. Press the [MENU] key to open the menu.
2. Operate the trackball to select “3. PANEL
DIMMER”.
3. Pressthe[RANGE] key to selectlevelde-
sired.
4. Press the [MENU] key again to erase the
menu.

2-9
2.22 Selecting Ranges
This radar has 14 ranges, some which you
may not require. You can select or deselect
ranges as follows.
1. Press the [MENU] key to open the menu.
2. Operate the trackball to select “6.
RANGE”.
3. Press the [RANGE] key to place the un-
derline under the range you want to se-
lect or deselect.
4. Press the [RING] key to select or dese-
lect.
5. Repeat step 4 and 5.
Maximumnumber of rangesisall ranges.
Minimum number of ranges is two.
2.23 EBL/Cursor Bearing
Reference
EBL and cursor bearing can be displayed
relative to own ship’s heading (Relative) or
with reference to North (True).
Note: Magnetic compass or gyrocompass
connection required for true bearing.
1. Press the [MENU] key to open the menu.
2. Operate the trackball to select “9. EBL/
+CURSOR”
3. Press the [RANGE] key to select “TRUE”
or “REL (Relative)”.
2.24 Guard Alarm
The alarm allows the operator to set the de-
sired range (0 to maximum range) and bear-
ing(0to360degrees) for a guard zone,called
AutoIn/Outalarm.Whenships, islands, land-
masses, etc. go into (or go out of) the guard
zone an audible alarm sounds to call the
operator’s attention.
Before setting the alarm, be sure the [GAIN]
control is properly adjusted, because the au-
dible alarm sounds when the fifth or more
levelquantization echoesgo into orgo out of
the guard zone.
1. Mentally create the guard zone you want
to display on-screen. See Figure 2-12.
2. Set upper (lower) left edge of the guard
zone with the cursor, and press the
[GUARD] key.
The indication “*GUARD” (asterisk blink-
ing) appears at the upper right-hand side
of the screen. See Figure 2-12 (2). The
asterisk indicates the guard zone is par-
tially set, but the alarm function has not
been actuated. It disappears once the
guard zone is set completely.
3. Moving the trackball clockwise, set the
lower (upper) right edge of the guard
zone. The guard zone now appears on
the display and alarm function has been
actuated, See Figure 2-12 (3).
Note: To create a 360 degree guard zone,
rotatethe cursor counterclockwise insteadof
clockwise.
4. Press the [GUARD] key again. The as-
terisk disappears and the alarm function
is actuated after three to five antenna
scannings, and then, the indication
“GUARD” is replaced by “G(IN)” or
“G(OUT)”.
5. Any ships, landmasses, etc. coming into
or going out of the guard zone will trigger
the audible alarm. If the audible alarm
sounds you can silence it by pressing the
[GUARD] key. When this is done the indi-
cation“GUARD”appearsin reversevideo.
6. Press the [GUARD] key again to restore
the audible alarm. “GUARD” lights in nor-
mal video.
7. To cancel both the guard zone and the
audible alarm, press and hold down the
[GUARD] key for three seconds.
Note 1: When the range is less than the half
of the guard zone range, the guard zone dis-
appears from the screen and “UP RANGE”
indication appears. If this happens, select a
rangewhichwillagaindisplay the guard zone
on the screen.