Navman FISH 4500/4600 Sonar Bottom display, Sonar 50/200 display, Sonar A-Scope 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-scopeis 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.

5-4 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-scopeis 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.

5-5 Sonar A-Scope display

To show the SonarA-Scope display, press DISP and select Sonar Tab, select Sonar A-Scopeand press ENT.

Use this to analyse the sonar data in detail and optimize the Gain settings.

Divider line between sonar history and A-scope

Gain setting (strongest echo for display)

Gain threshold (weakest echo for display)

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.

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.

24 NAVMAN FISH 4500/4600 Installation and Operation Manual