2. RADAR, CHART RADAR OPERATION
2-8
2.9 Echo Averaging
The echo averaging feature, which requires heading, position and speed data, effec-
tively 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 succes-
sive picture frames. If an echo is solid and stable over successive frames, it is present-
ed 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 mo-
tion 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 sta-
tionary ones.
Note 2: Do not use echo averaging under heavy pitching and rolling; loss of targets
can result.
Note 3: Echo averaging is turned off and the indication is greyed out when the heading
sensor signal is lost.
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:
Click the [EAV] button on the InstantAccess bar™ then click desired setting.
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 display-
ing high-speed targets. Select the setting best suited to your objective.
3: Stably displays unstable targets; distinguishes high-speed craft from sea clutter.
Echo averaging is turned off and the indication is greyed out when the performance
monitor or SART is active.
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