NorthStar 972 安装指导
SECTION THREE: Setting up the radar
Ethernet Radar Installation Manual, Rev. A
Page 21
6. Adjust the Auto Sea preset until most of the weak echoes for an 8nm radius are eliminated.
7. Zoom in to a 1.5nm range and verify that strong echoes from nearby vessels or land are not
7. Zoom in to a 1.5nm range and verify that strong echoes from nearby vessels or land are not
eliminated. If land or vessel echoes are eliminated, follow the above steps to decrease the sea
clutter preset.
clutter preset.
Setting the STC Curve
The Sensitivity Time Control (STC) attempts to compensate for the high strength of nearby echoes
compared with the very weak echoes from distant objects. It lowers the receiver gain when the pulse
is transmitted, and raises the gain as echoes return from longer distances. Ideally, the result is that all
echoes are displayed with strengths proportional to the object reflectivity. A graph of the receiver
gain versus time is called the STC curve. The user can select different curve shapes, if required for
special applications.
compared with the very weak echoes from distant objects. It lowers the receiver gain when the pulse
is transmitted, and raises the gain as echoes return from longer distances. Ideally, the result is that all
echoes are displayed with strengths proportional to the object reflectivity. A graph of the receiver
gain versus time is called the STC curve. The user can select different curve shapes, if required for
special applications.
Setting the STC curve to a lower number applies the Sea Clutter function closer to the vessel. A larger
value applies Sea Clutter over a wider area.
value applies Sea Clutter over a wider area.
Curve 4 is recommended for all normal applications.
Higher curve numbers might be appropriate for installations where the radar antenna is located high
on the vessel.
on the vessel.
Lower curve numbers might be appropriate for installations where the radar antenna is located low
on the vessel.
on the vessel.
To select a different curve:
1. On the radar screen, press
Adjust radar...
and then
Presets...
.
2. Press
STC curve
and use the keypad to enter a curve number from 0 to 8.
Setting the Heading Calibration
The heading calibration rotates the radar image on the screen to line it up with the displayed chart
and the compass. Accurate heading calibration is especially important when overlaying the radar
image onto the chart. (radar/chart image alignment).
and the compass. Accurate heading calibration is especially important when overlaying the radar
image onto the chart. (radar/chart image alignment).
1. Make sure the heading sensor is calibrated according to the manufacturer’s instructions.
When sea trialing the vessel, set a straight course for a solid object such as a lighthouse, jetty,
or radar nav marker that is at least 1 nm away as referenced on the chart.
or radar nav marker that is at least 1 nm away as referenced on the chart.
2. Turn on the radar overlay feature: Press CHART to display the chart and press
Overlay
to
display radar echoes overlaid on the chart.
3. Set the chart rotation to North-up by pressing
Rotate
several times until
North up
is
displayed.
4. Find a target that appears on both the radar image and the chart. An appropriate choice
would be a land pattern or solid object about a mile or more from the vessel, with a fixed
point, such as a jetty, lighthouse, or pier. (Avoid beaches and buoys as these may have radar
images that don’t align with the chart.) Zoom in as necessary to place identifiable objects
near the outer edge of the screen.
point, such as a jetty, lighthouse, or pier. (Avoid beaches and buoys as these may have radar
images that don’t align with the chart.) Zoom in as necessary to place identifiable objects
near the outer edge of the screen.
5. Press
the
Control
key so that it displays
Radar
.
6. Press
Adjust radar...
and
Setup...
.