Furuno FAR-2107(-BB) - Manual (Page 66)

1. RADAR OPERATION
1-44
1.27 Echo Averaging
The echo averaging feature effectively reduces sea clutter. Echoes received
from stable targets such as ships appear on the screen at almost the same
position every rotation of the antenna. On the other hand, unstable echoes such
as sea clutter appear at random positions.
To distinguish real target echoes from sea clutter, echoes are averaged over
successive picture frames. If an echo is solid and stable over successive frames,
it is presented in its normal intensity. Sea clutter is averaged over successive
scans and its brilliance reduced, making it easier to discriminate real targets
from sea clutter.
Echo averaging uses scan-to-scan signal correlation technique based on the
true motion over the ground of each target. Thus, small stationary targets such
as buoys will be shown while reducing random echoes such as sea clutter. True
echo averaging is not however effective for picking up small targets running at
high speeds over the ground.
Note 1: With echo average active it is harder to detect high-speed targets than
stationary ones.
Note 2: Do not use the echo averaging function under heavy pitching and
rolling; loss of targets can result.
Note 3: Echo averaging can be used without a heading sensor. For further
details, contact your dealer.
Note 4: Echo averaging requires heading, position and speed data.
Before using the echo averaging function, reduce sea clutter with the A/C SEA
control. Leave a little sea clutter on the screen so as not to erase weak targets.
Then, do as follows:
Left-click the EAV indication at the left side of the display.
OFF: Echo averaging OFF
1, 2:
Detects targets hidden in sea clutter. "2" is more effective than "1" in
detecting targets hidden in strong sea clutter. However, "1" is more
effective than "2" in displaying high-speed targets. Select the setting
best suited to current conditions. For effective monitoring of
high-speed craft, you should use "2" together with Wiper.
3: Stably displays unstable targets; distinguishes high-speed craft from
sea clutter.
Note: Echo averaging can also be adjusted from the PICTURE box.