Raymarine L750 Operations Instructions download pdf (Page 57)

Chapter 3: Operating Instructions

A-Scope (Bottom Coverage) Key

On the Downlook display, the bottom graph is “drawn”

after

the

Fishfinder receives several echoes. This has the effect of showing a

record of the bottom contour. The A-scope displays raw sonar data

directly from the transducer beam. This gives you a “real time” image of

fish and bottom structure directly below the transducer. This function is

very useful in showing the strength of the echo returned from a fish.

Stronger fish echoes on the A-scope display will appear wider. Weaker

echoes appear as narrow bands closer to the horizontal center of the A-

scope image.

Figure 3-14 shows a sample of the A-Scope display. The left section of

the A-Scope display shows a section of the Downlook display. All of the

features are the same. The right section shows the A-Scope image.

A-Scope image

This shows the beam of sound waves extending down from the

boat, and spreading as it moves through the water. Any fish or

objects which are positioned under the boat will appear on the

Fig. 3-14 Downlook Page with A-Scope

A-scope

image

Bottom

coverage

Part of

downlook

page

Fish

image

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Raymarine L750 Operations Instructions Page 57