How To Measure Range And Bearing To A Target; How To Eliminate Weak Echoes; Change Sensitivity Of Tvg Curve - Furuno FSV-25S Operator's Manual

2.5

How to Measure Range and Bearing to a Target

Operate the trackball to place the cursor on the target you want to measure the range
and bearing. The range, bearing and depth to the target appear at the upper left corner
of the screen.
Note 1: Trackball position may also be shown in latitude and longitude. For further de-
tails, see page 6-12.
Note 2: The bearing display is available in four formats. See page 6-12.
2.6

How to Eliminate Weak Echoes

Echoes from targets such as bottom and fish return to the transducer in order of dis-
tance to them, and when we compare their intensities at the transducer face, those
from nearer targets are generally stronger due to little propagation attenuation and lit-
tle absorption. If these echoes are displayed directly on the screen, the size of the dis-
played echo from the same school of fish may change with distance, making it difficult
to judge the actual size of the school of fish. To overcome this inconvenience use the
TVG curve function. This function compensates for propagation loss of sound in water;
amplification of echoes on short range is suppressed and gradually increased as
range increases so that similar targets are displayed in the similar intensities irrespec-
tive of the ranges to them.
2.6.1

Change sensitivity of TVG curve

Four TVG curves are available and they vary the gain from large to small.
1. Press the MENU/ESC key to open
the main menu.
2. Click [Gain Setting].
3. Press the H/V/S key to select the [H1]
or [H2] tab.
TRACKBALL DATA
Slant range
Horizontal range
Depth
B Relative or
True bearing
Cursor L/L position
Cursor
B
Heading line
Own ship mark
34°56.789N
123°45.678E
Gain Setting
H1 P1
TVG Curve
Near Gain
Near Gain Distance
Far Gain
Far Gain Distance
AGC
Noise Suppress
2. HORIZONTAL MODE
Quit
H2 P1 V P1
: 15Log
: 5.0
: 400m
: 5.0
: 400m
: 5.0
: 2.0
2-9