Suppressing Precipitation Clutter; Interference Rejector - Furuno FR-1710 Operator's Manual

1.16 Suppressing Precipitation
Clutter
The vertical beamwidth of the scanner 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,
or hail) in the same manner as normal tar-
gets. Figure 1-12 shows the appearance of
rain clutter on the display.
The A/C RAIN control adjusts the receiver
sensitivity as the A/C SEA control does but
rather in a longer time period (longer range).
Clockwise rotation of this control increases
the anti-clutter effect.
A/C RAIN control
OFF
Figure 1-12 Effect of A/C RAIN control

1.17 Interference Rejector

Mutual radar interference may occur in the
vicinity of another shipborne radar operating
in the same frequency band (9 GHz). It is
seen on the screen as a number of bright
spikes either in irregular patterns or in the
form of usually curved spoke-like dotted lines
extending from the center to the edge of the
picture. This type of interference can be re-
duced by activating the interference rejector
circuit.
The interference rejector is a kind of signal
correlation circuit. It compares the received
signals over successive transmissions and
suppresses randomly occurring signals.
A/C RAIN control
adjusted
There are three levels of interference rejec-
tion depending on the number of transmis-
sions that are correlated. These are indicated
by the legends IR1, IR2 and IR3 at the lower-
left position of the screen.
Figure 1-13 Interference
To activate the interference rejector;
1. Press the [MENU] key.
2. Press the [5] key twice to select ECHO
SIG.
ECHO SIG
1. TGT COLOR
2. ECHO AVG
3. INT REJ
4. N REJ
5. ENHANCE
6. 2ND ECHO
7. CONTRAST
8. CLTR SWEEP
9. SWEEP LVL
0. CNTR ENHANCE OFF ON
Figure 1-14 ECHO SIG menu
3. Press the [3] key to select interference
rejection level (OFF, 1, 2, or 3) from the
INT REJ field.
4. Press the [ENTER/SELECT] key.
5. Press the [MENU] key.
YEL GRN COLOR
OFF 0.5 1 2 3
OFF 1 2 3
OFF ON
OFF ON
OFF ON
1 2 3
OFF ON(LINK) ON(FIX)
1 2 3
1-13