Echo Averaging - Furuno FR1500 Mk3 Operator's Manual

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CURSOR
(a) Select location with cursor
Note: The display is automatically reset to 75% of the range in use whenever the cursor is placed at
an edge of the effective display area. Note also that the heading marker (small circle on the bearing
scale) leaves the heading line on off-centered display, always indicating the correct direction of the
own ship heading.

1.24 Echo Averaging

The echo average feature effectively suppresses sea clutter. Echoes received from stable targets
such as ships appear on the screen at almost the same position every rotation of the scanner. On
the other hand, unstable echoes such as sea clutter appear at random positions.
To distinguish real target echoes from sea clutter, echo average performs scan-to-scan correlation.
Correlation is made by storing and averaging echo signals over successive picture frames. If an
echo is solid and stable, it is presented in its normal intensity. Sea clutter is averaged over
successive scans resulting in the reduced brilliance, making it easier to discriminate real targets
from sea clutter.
To properly use the echo average function, it is recommended to first suppress sea clutter with the
A/C SEA control and then do the following:
1. Press the [F1] key.
2. Press the [5] key twice to select ECHO AVG.
ECHO AVG
1. VECTOR T/R
2. PULSE
3. INT REJ
4. STRETCH
5. ECHO AVG
6. CONTRAST
7. N REJ
8. DISP SEL
9. PM
0. SART
3. Press the [5] key to select echo averaging level desired from the ECHO AVG field.
OFF: No averaging effect
0.5: Distinguishes small targets from sea clutter.
1: Helps distinguish targets from sea clutter and suppresses brilliance of unstable echoes.
2: Distinguishes small stationary targets such as navigation buoys.
3: Stably displays distant targets.
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CURSOR
(b) Press SHIFT key to offcenter
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