A-Scope (Bottom Coverage) Key; Fig. 3-14 Downlook Page With A-Scope - Raymarine L750 Operating Handbook

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
Part of
downlook
page

Fig. 3-14 Downlook Page with A-Scope

49
A-scope
image
Fish
image
Bottom
coverage