Relation Between Bottom Echo And Tilt Angle - Furuno FSV-25 Operator's Manual

2. HORIZONTAL MODE
Range (m)
60, 100
150, 200
300, 400
500, 600
800
1000
Over 1200
Range (m)
60, 100, 150
200
300, 400
500, 600
800
1000
Over 1200
For example, when the RANGE control, TILT control and AUTO TILT key are set to
800 m, 8° and width (1) respectively, the tilt angle changes at each transmission as
follows: 8° → 9° → 8° → 7° → 8°.
Note 1: The AUTO TILT key is inoperative when the target lock function is active or
is made active. Auto tilt is available when the target lock is OFF.
Note 2: If the picture set with auto tilt is not visible, disable auto tilt and try again.
2.4.3

Relation between bottom echo and tilt angle

The figure below illustrates how two schools of fish "a" and "b" are displayed on the
screen using three different tilt angles.
Case 1: Tilt angle 30° to 40°: This tilt angle will display the entire bottom since it is
captured by the full width of the beam. The school of fish is obscured by the bottom.
Case 2: Tilt angle 10° to 20°: This tilt angle will only display half the bottom since it
is captured by only the lower half of the beam. The school of fish is located above the
bottom.
Case 3: Tilt angle 0° to 5°: This tilt angle may or may not capture the bottom since
the returning bottom echo is weak. The school of fish is located close to the bottom.
2-6
Automatic tilt angle (narrow) with AUTO TILT key
Width 1 Width2
±4°* ±6°*
±2° ±4°
±1° ±2°
±1° ±2°
±1° ±2°
±1° ±2°
±1° ±2°
Automatic tilt angle (wide) with AUTO TILT key
Width 1 Width2
±10° ±16°
±10° ±16°
±10° ±16°
±8° ±16°
±6° ±12°
±4° ±8°
±2° ±4°
Width3
±8°* Period: One transmission
±6°* Note: Tilt angle changes in 2° in-
±4°* crements for asterisk-marked
±3° width; 1° increments for all other
±3° widths.
±3°
±3°
Width3
±20° Period: One transmission
±20°
±20°
±20°
±16°
±12°
±6°
Set tilt angle
Period
Period