Furuno color video plotter GD1720C - Manual (Page 53)

2. RADAR OPERATION
2-22
2.20 Echo Averaging
The echo average feature, which requires a Model 18x4/19x4 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: No averaging
LOW: Helps distinguish targets from sea clutter and suppresses brilliance of unstable
echoes.
MED: Distinguishes small stationary targets such as navigation buoys.
HIGH: Stably displays distant targets.
4. Press the RETURN soft key to finish.
(a) Echo average OFF (b) Echo average ON
Effect of echo averaging