Gain, Threshold And Range - NorthStar Explorer 660 Installation And Operation Manual

8-5 Gain, threshold and range

The Explorer has three settings that affect the
sonar display:
Gain: The gain of the sonar receiver. The
•
gain should be high to display good detail,
but if the gain is too high then information
from the strong bottom signal is lost and
false echoes might be displayed. There
is a separate gain setting for each sonar
frequency, 50 kHz and 200 kHz.
Threshold: Return echoes less than the
•
threshold are ignored. The threshold should
be as low as possible, but if the threshold is
too low, unwanted noise will be displayed.
Threshold is set as a percentage of gain. For
example, if the threshold is 50 %, then return
echoes less than 50 % of the maximum signal
are ignored. There is a separate threshold
setting for each sonar frequency, 50 kHz and
200 kHz.
To display the current settings for gain and
threshold, select a sonar display and press
ENTER:
This display is called the gain window.
Range: The vertical depth covered by a
•
Explorer 660 sonar display. For example, if the
range is 100 m, then the sonar display shows
depths between 0 and 100 m. The range is
displayed at the bottom, right corner of a
sonar display.
If the bottom is deeper than the specified
depth range, it will not be shown on
the display.
The Explorer 660 has three operating modes,
Cruise, Fishing and Manual (see section 8-1).
In Cruise and Fishing modes, the Explorer 660
automatically adjusts gain and threshold for
good performance and adjusts range to always
show the bottom. In manual mode, you can hand
adjust the settings.
Northstar Explorer 660 Installation and Operation Manual
8-5-1 Changing between automatic and
manual modes
Select a sonar display before changing mode (see
section 9).
a Using an automatic mode
Press GOTO/AUTO and select Cruise or
Fishing (see section 8-1). The Explorer
660 will adjust gain, threshold and range
automatically.
b Using manual mode
Press GOTO/AUTO and select Manual. The
Explorer 660 reverts to your last manual
settings (see section 8-1).
c Adjusting gain or threshold manually
1 Press ENTER to display the gain window:
2 Press or
to adjust.
3 Press or
If the Explorer 660 is in Cruise or Fishing
modes, it will stop adjusting gain and
threshold automatically but will continue to
adjust range automatically.
Tip: Use the A-scope display to help
set gain or threshold manually (see section
8-5-2).
To revert to automatic:
Either press GOTO/AUTO and select Cruise
•
or Fishing.
Or press ENTER to display the gain window,
•
select Manual and press
The Explorer 660 will not adjust threshold
automatically; if gain is manual it will stay
manual.
d Adjusting range manually
Either press
•
decrease range.
Or press MENU, select Range and select
•
Manual. Range does not change.
If the Explorer 660 is in Cruise or Fishing
modes, it will stop adjusting range
automatically but will continue to adjust gain
and threshold automatically.
to select the setting
adjust the setting.
.
or to increase or
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