Bottom echogram description
An echogram will normally dominate each Channel view in the ME70 presentation. The echogram contains information about the acoustical values. The settings made in the Echogram dialog box specifies displayed information type, while the settings in the Colour Scale dialog box is used to control the presentation. You can add selection of markers to the echogram presentation to enhance and/or add information.The Bottom echogram shows the echoes over and below the sea bottom contour. Since this echogram is referenced to the sea bottom, the sea surface will vary with the actual depth, while the bottom is drawn flat. You can select the start range (the depth from which the echogram starts) and the vertical range (the vertical "length" of the echogram) by means of the Start Range and Range settings. Both the Range and the Start Range functions are located on the Main menu.
How to open
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An echogram is displayed for each channel view, however it is possible to toggle between different types of echograms.
To activate Bottom echogram, click in the chosen view to make it "active". Select Echogram on the Active menu. In the Echogram dialog box set Echogram Type to Bottom.From Echogram shortcut menu you will be able to chose surface or bottom echogram to be displayed. Right-click in the view to open the shortcut menu.
Description
A Bottom echogram is mainly used when you want to examine the echoes from fish close to the sea bottom. Set up the Start Range and Range depths to hide the surface and place the sea bottom contour at the middle of the echogram. You can investigate the sea bottom conditions and hardness, and detect fish.
Note
The echogram is only drawn for pings that have a successful bottom detection.
Since the Bottom echogram is referenced to the bottom, the Start Range value must be negative. If you wish to start your echogram from 10 meters above the bottom, you must set the Start Range to –10 m. The Range setting defines the vertical range from the start depth and down.
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A This is the start depth of the echogram
In a Bottom echogram you will probably wish to start the echogram from a fixed distance above the bottom. To do this, you must set the  Start Range to a negative value, for example -10 m. This negative value defines how many meters above the bottom the echogram will start.
The  Range value defines the vertical "height" of the echogram. To make sense, the value must be positive, and numerically larger than the chosen Start Range. If you have chosen to start your echogram from -10 m, the range must be larger than 10 meters, for example 20 meters.
B This is the bottom (seabed)
The bottom is shown with a strong contour. Since the echogram is referenced to the sea surface, the bottom will vary with the actual depth.
Different bottom conditions will have a visual effect on how the bottom echo is drawn. A hard bottom (rock) will give you a stronger echo - and thus a darker colour - than a soft bottom (mud or silt).
The Echogram page in the Echogram dialog box allows you to make adjustments to the bottom contour. You can add a black bottom line, and a white line to make the bottom "stand out".
C Transducer identification
This text identifies the transducer - and thus also the channel - used to create the echogram. In this context, the phrase channel is used as a common term to identify the combination of transceiver, transducer and operating frequency.
D This is the scope view
The Scope view is used to indicate how strong each echo is. The colour and the length of each line reflects the received echo amplitude.
E These are the labels
Small labels are shown in the bottom left and right corners of the view. These labels can contain time or distance to identify the horizontal axis of the echogram. You can hide the labels from view.
•  None: The labels are hidden
•  Auto: The horizontal scale is set automatically
•  Time: The horizontal scale is defined by time. The time shown in the bottom right corner of the echogram is then the current time (now).
•  Distance: The horizontal scale is defined by distance. The distance shown in the bottom right corner of the echogram is then 0 nautical miles (starting point).
The labels can be changed on the Horizontal Axis page in the Echogram dialog box.
F This is the lower end of the chosen depth range
This depth is normally a few meters below the bottom contour, depending on the chosen range. The total echogram range (A) to (F) is defined with the Range button on the Main menu.
Example
Start Range and Range in bottom-related echogram
In a bottom echogram, set the Start Range value to –5 metres. This will make the echogram start from 5 metres above the sea bottom. Set Range to the 5 metres plus 10 = 15 metres. The echogram will now show the area from 5 metres above the depth, and down to 10 meters "below" the sea bottom. The sea bottom contour will appear as a flat line.
Details
To activate a field and hence a channel, you must first click in the field. By doing so the menus and options available will adjust to the activated field and also apply to the active channel for this field. In this context , the phrase channel is used as a common term to identify the combination of transceiver, transducer and operating frequency.
You can easily change the physical size and shape of the fields. Click on the grey lines between the fields and drag to new size. Note that this will cause one field to increase in size and another to decrease.
Right-click in the active field and select Hide View from the shortcut menu to close the field.
Right-click in any of the fields in the active channel and select Configure Window to be able to reopen a field.Select the field(s) you want to re-open by ticking of the name in the Show Views listClick on the Apply button for the field to appear