1. OPERATIONAL OVERVIEW
1-25
1.23 Echo Averaging
The echo averaging feature effectively reduces sea clutter. Echoes received from sta-
ble targets such as ships appear on the screen at almost the same position every ro-
tation 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 the echo averaging function under heavy pitching and rolling; loss
of targets can result.
Note 3: 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:
Select the [EAV] box at the left side of the screen, then press the left button to select
the desired level of echo averaging.
• [OFF]
• [1], [2]
• [3]
: Echo averaging is not enabled
: Detects targets hidden in sea clutter. [2] is more effective than [1] in detect-
ing 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.
: Stably displays unstable targets; distinguishes high-speed craft from sea
clutter.
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