Echo Averaging - Furuno NAVNET 1722 Operator's Manual

2. RADAR OPERATION
2.20

Echo Averaging

The echo average feature, available with selection of a Model 1833/C series
network radar as radar source, effectively suppresses sea clutter. Echoes
received from stable targets such as ships appear on the screen at almost the
same position during 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, 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. If not displayed, press the [HIDE/SHOW] key to display the radar soft keys.
2. Press the SIGNAL PROC. soft key.
3. Press the E. AVG soft key to select desired echo averaging.
OFF:
LOW:
MED:
HIGH: Stably displays distant targets.
The display shows EAV L, EAV M or EAV H when echo averaging is on.
4. Press the RETURN soft key to finish.
2-28
No averaging
Helps distinguish targets from sea clutter and suppresses brilliance
of unstable echoes.
Distinguishes small stationary targets such as navigation buoys.
(a) Echo average OFF
Effect of echo averaging
(b) Echo average ON