Furuno FR-1710 manual Echo Averaging, Echo SIG menu

Note: The display is automatically shifted by 75% of the range in use whenever the cur- sor is placed at an edge of the effective dis- play area.

1.24 Echo Averaging

The echo average feature effectively sup- presses sea clutter. Echoes received from stable targets such as ships appear on the screen at almost the same position every ro- tation of the scanner. On the other hand, un- stable 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 clut- ter is averaged over successive scans result- ing 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 fol- lowing:

1.Press the [MENU] key.

2.Press the [5] key twice to select the ECHO SIG menu.

	ECHO SIG
1.	TGT COLOR	YEL			GRN		COLOR
2.	ECHO AVG	OFF			0.5	1	2 3
3.	INT REJ	OFF			1	2	3
4.	N REJ	OFF			ON
5.	ENHANCE	OFF			ON
6.	2ND ECHO	OFF			ON
7.	CONTRAST	1	2		3
8.	CLTR SWEEP	OFF		ON(LINK) ON(FIX)
9.	SWEEP LVL	1	2		3
0. CNTR ENHANCE		OFF			ON

Figure 1-23 ECHO SIG menu

3.Press the [2] key to select echo averag- ing level (OFF, 0.5 1, 2, 3) from the ECHO AVG field.

OFF: No averaging effect

0.5: Distinguishes small targets from sea clutter.

1:Distinguishes targets from sea clutter and suppresses brilliance of unstable echoes.

2:Distinguishes small stationary targets such as navigation buoys.

3:Stably displays distant targets.

4.Press the [ENTER/SELECT] key to con- clude your selection followed by the [MENU] key to close the menu.

(a) Echo average OFF (b) Echo average ON

Figure 1-24 Echo averaging

Echo averaging uses scan-to-scan signal cor- relation technique based on the true motion over the ground of each target. Thus, small stationary targets such as buoys will be shown while suppressing random echoes such as sea clutter. True echo average is not however effective for picking up small targets running at high speeds over the ground.

Echo average requires log and compass sig- nals. If you wish to use this feature without a compass signal, consult a FURUNO repre- sentative.

Manual speed entry is done at the menu item MAN SPD on the OTHER menu, which is ac- cessed by pressing the [MENU] and [0] (twice) keys.

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