Navman FISH 4500/4600 - Manual (Page 24)

5-4 Sonar 50/200 display
To show the Sonar 50/200 display, press DISP
and select Sonar Tab, select Sonar 50/200
and press ENT.
This shows a split display, with the 50 kHz sonar
history on the left side and the 200 kHz sonar
history on the right side. Gain settings can be
set independently for each frequency. Range
settings apply to both sections of the display.
To change items, press MENU until the Op-
tions menu is shown. Gain is explained in
section 4-4 Gain.
Range is explained in section 4-5 Range.
A-scope is explained in section 5-5 Sonar A-
Scope display.
Data header is explained in section 5-1 Sonar
display.
Split ratio is explained in section 5-2 Sonar
Zoom display.
5-3 Sonar Bottom display
To show the Sonar Bottom display, press DISP
and select Sonar Tab, select Sonar Bottom
and press ENT.
This shows a split display, with the sonar history
on the right side and the zoom section on the
left. The bottom signal is shown as a flat trace
in the centre of the zoom section.
Showing the bottom as a flat trace can make it
easy to compare the echo strengths shown in the
bottom signals. This can help to identify the type
of bottom and objects close to the bottom.
The zoom bar can only indicate the zoom range.
It cannot indicate the zoom offset as this changes
for each sounding displayed on the display.
The zoom bar is fixed in the middle of the
display.
See section 4-5 Range, for information about
adjusting the Zoom Range and Zoom Offset.
To change items, press MENU until the Options
menu is shown.
Gain is explained in section 4-4 Gain.
Range is explained in section 4-5 Range.
A-scope is explained in section 5-5 Sonar
A-Scope display.
Data header
is explained in section 5-1
Sonar display.
Bottom lock
and Split ratio are explained
in section 5-2 Sonar Zoom display.
5-5 Sonar A-Scope display
See section 4-4 Gain, for more information.
The strength of an echo at a particular depth
is shown by the length of the horizontal line at
that depth. A strong echo produces a long line
whereas a weak echo produces a short line.
To change items, press MENU until the Options
menu is shown.
Gain
is explained in section 4-4 Gain.
Range is explained in section 4-5 Range.
Data header is explained in section 5-1
Sonar display.
Split ratio
is explained in section 5-2 Sonar
Zoom display.
Fish recognition
The echo strengths shown on the A-scope can
be useful in recognising the type of fish. Different
species of fish have different sizes and shapes
of swim bladders. The air in the swim bladder
reflects the ultrasonic pulse, so the strength of
the echo varies between fish species according
to the size and shape of the swim bladder.
The user can define the level of the weakest and
strongest echoes to be shown on the sonar dis-
plays, by using the Gain and Threshold settings.
Divider line
between sonar
history and
A-scope
Gain setting
(strongest echo
for display)
Gain threshold
(weakest echo
for display)
To show the Sonar A-Scope display, press DISP
and select Sonar Tab, select Sonar A-Scope
and press ENT.
Use this to analyse the sonar data in detail and
optimize the Gain settings.
FISH 4500/4600 Installation and Operation Manual 24 NAVMAN