Relative Bearing Alignment - Furuno 1761 MARK-3 Installation Manual

Cursor
SEL MENU BY TRKBALL :
MENU
ITEMS WITH RANGE KEY
03590361xx
1 HD ADJ
2 TMG ADJ
3 MAG / GYRO
4 NM / KM
No. of hours radar transmitted
No. of hours radar turned on
Figure 3-2 INSTALLATION menu
4. With the trackball, select "TMG ADJ".
SEL MENU BY TRKBALL :
MENU
ITEMS WITH RANGE KEY
1 HD ADJ
2 TMG ADJ
3 MAG / GYRO
4 NM / KM
Figure 3-3 Timing adjustment
5. While looking at the target selected at step
2, press the [RANGE +] key if the target
is pulled inward, or press the [RANGE -]
key if the target is pushed outward.
6. Press the [MENU] key to complete the
adjustment.

3.3 Relative Bearing Alignment

You have mounted the scanner unit facing
straight ahead in the direction of the bow.
Therefore, a small but conspicuous target
dead ahead visually should appear on the
heading mark (Zero degree).
In practice, you will probably observe some
small error on the display for most installa-
tions because of the difficulty in achieving
accurate initial positioning of the scanner unit,
The following adjustment will compensate for
this error.
3-2
Program No.
TOTAL ON TIME
00000 : 00
TOTAL TX TIME
00000 : 00
DSPL STR TGT
ON SHORT RNG.
PRESS -/+ KEY NM
TO STRAIGHTEN.
If you don't know how to do it well, it's best
you leave this part to a qualified technician.
(Remember that the scanner housing fixing
bolts remain untightened. They should now
be secured if the following alignment is not
necessary.)
1. Identify a suitable target (for example, ship
or buoy) at a range between 1/8 to 1/4
miles, preferably near the heading mark.
To minimize error, keep echoes in the
outer half of the picture by changing the
range.
2. Measure the bearing to the target by op-
erating the trackball. The bearing is shown
at the bottom center of the screen.
3. Using a compass card, visually find the
relative bearing to the target.
4. Compare the bearing measured in step 2
and 3 above and calculate the direction
and magnitude of the bearing error. If the
error is within 30 degrees go to step 9, to
correct the error at the display unit. If the
error is greater than 30 degrees first make
initial adjustments at the scanner unit and
then fine tune at the display unit.
Heading
Mark
A
Bearing on Radar
Figure 3-4 Calculating Bearing Error
5. Press and hold down the [MENU] key
(about 10 seconds) until the INSTALLA-
TION menu appears.
6. With the trackball, select "1. HD ADJ". The
heading marker and tuning range mark-
ers appear. See Figure 4-5 (a).
7. Identify a suitable target (for example, ship
or buoy) at a range between 1/8 to 1/4
miles, preferably near the heading mark.
To minimize error, keep echoes in the
outer half of the picture by changing the
range.
Target
B
Own ship
Bearing on Chart