Furuno FR-1500 MARK-3, User Manual

Page: 49 / 125

-1.35-
1.36 Echo Stretch, Contrast, Enhanced Video
On long ranges target echoes tend to shrink in the bearing direction, making them difficult to see.
On short and medium ranges such as 1.5, 3 and 6 nm scales, the same size targets get smaller on
screen as they approach the own ship. These are due to the inherent property of the radiation
pattern of the antenna. To enhance target video, use the echo stretch function. There are two
types: echo stretch 1 (ES1) to enlarge in bearing direction for long range detection, and echo
stretch 2 (ES2) to enlarge in range direction on 1.5-6 nm scales.
1.36.1 Echo stretch
1. Press the [F1] key.
2 Press the [4] key twice to display the ECHO SIG menu.
3. Press the [4] key to select echo stretch function desired. A selected
level appears at the lower left-hand position. Each selection works
as in the figure below.
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
ES OFF
ES1
– Enlarged in bearing
direction
Use on range 1.5-12 nm
ES2
– Enlarged in range
direction. Invalid at P/L S1
and S2
Use on range 1.5-6 nm
Notes:
1) If the 1.5 nm range is preset for pulselength of S1 or S2, and the 3 nm scale for S2, the
echo stretch is not available on those range scales.
2) The echo stretch magnifies not only small target pips but also returns (clutter) from sea
surface, rain and radar interference. For this reason make sure these types of interference
have been sufficiently suppressed before activating this function.
1.36.2 Contrast
Contrast is adjustable in 3 levels according to the radar video sampling level. Press [F1], [6] and
select the level so that the picture shows up most clearly from the background.