Furuno FR-1710 - Manual (Page 30)

1-16
3. Turn the VRM rotary control until the
range marker on the No. 1 EBL aligns with
target 2 in Figure 1-18. The active VRM
readout at the lower-right corner of the
screen indicates the distance between the
two targets.
4. To return the EBL origin to the own ship
position, press the [EBL OFFSET] key
again.
You can repeat the same procedure on third
and fourth targets by using the No.2 EBL and
No.2 VRM.
Bearing is shown relative to own ship with
suffix “R” or as a true bearing with suffix “T”
depending on EBL relative/true settings on
the OTHER menu.
No. 1 EBL
VRM
0.50NM
No. 1 VRM
A
B
Bearing from target A
to target B Range between
target A and
target B
EBL
80.0 R
Figure 1-18 Measuring range and bearing
between two targets
1.22 Setting a Target Alarm Zone
CAUTION
The target alarm feature should never be
relied upon as the sole means for detecting
the risk of potential collision. The operator
of a ship is not relieved of the responsibility
to keep lookout for avoiding collisions,
whether or not the radar is in use.
The target alarm serves to alert the naviga-
tor to targets (ships, landmasses, etc.) en-
tering a certain area, with visual and audible
alarms.
Note: The target alarm is given to targets
having a certain level of echo strength. This
level does not always imply a landmass, reef,
ships or other surface objects but can mean
returns from the sea surface or precipitation.
Properly adjust the GAIN, A/C SEA, and A/C
RAIN controls to reduce noise to avoid gen-
eration of the guard alarm against false tar-
gets.
The zone has a fixed width of 0.5 nm in the
radial direction (depth) and is adjustable only
within 3.0 to 6.0 nm from own ship. The outer
and inner boundaries can be set at any dis-
tance. The sector of the zone can be set any-
where between 0 and 360 degrees in any
direction.
To set target alarm zones:
1. Press the [MENU] key.
2. Press the [3] key twice to show the TGT
ALARM menu.
TGT ALARM
1. AREA NO1 NO2
2. MODE1 IN OUT
3. MODE2 IN OUT
Figure 1-19 TGT ALARM menu
2. Press the [1] key to select target alarm
zone to use; NO1 or NO2.
3. Press the [ENTER/SELECT] key.
4. Press the [MENU] key.
5. Place the cursor (+) at point “A” (see fig-
ure below) using the trackball. Press the
[GZ ALARM] key. GZ1 (or GZ2) SET ap-
pears. When both alarms are prepared
the active alarm is circumscribed.
6. Move the cursor (+) to point “B” and press
the [GZ ALARM] key again. Then, an echo
watch zone as illustrated is created and
the label IN (or OUT) replaces SET at the
lower-right corner of the screen.