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Northstar M121/M84 Installation and Operation Manual 75
Press
MENU
twice, then select Sonar:
Frequency
There is a choice of: 200 kHz, 50 kHz and
Mixed. For information about selecting a
suitable frequency for the water conditions, see
section 9-3.
Scroll speed
Use this to set the scroll speed on the display.
There is a choice of: Very Fast, Fast,
Medium, Slow and Pause. The depth of
the water also affects the speed of the display.
Faster scroll speeds combined with a slow
boat speed (typically between 2 and 6 knots)
shows the most fish detail. Medium or Slow
scroll speeds result in sonar information being
displayed over a longer period, but with less
detail (see Section 9-2).
Fish symbols
The Instrument always displays echoes from
fish (fish arches, see section 9-4). If fish symbols
are on, a symbol is displayed over the arch (see
section 9-4). The options are:
• Off: No fish symbol is displayed.
• Fun or Normal: A fish symbol is displayed.
19-3 Setup > Sonar
Fish depth labels
When this is turned on, the depth of a fish is
printed next to the fish arch.
Fish filter
Use this to select the minimum fish size that will
be displayed as a fish symbol and to trigger the
Fish alarm. The options are: Small, Medium
and Large.
Fish sensitivity
Selects the minimum strength fish echo that
will be displayed as a fish symbol. Higher values
will display more fish symbols.
Digit size
Use this to remove or change the size of the
depth window on the sonar windows. There is a
choice of: Small, Medium and Large.
Palette
Use this to select a color palette. Each color
within the palette represents a different echo
strength, as shown on the sonar windows.
There is a choice of five color palettes: Black,
Blue, White, Vivid and 8 color. The first
four palettes display more detail, and each color
covers a 1.5 dB signal range. The 8 color
palette displays less detail, and each color
covers a 3 dB signal range.
Interference filter
No filter, normal setting.
Filters the echo signal to remove spiky
interference such as engine noise or depth
sounders on nearby boats.