Furuno 1830 - Page 35

To obtain a rough raeasurement of the range to a target pip, the fixed range
rings are used. The fixed range rings are the solid rings aoDering on the
CRT. These rings are activated/deactivated by pressing the touchpad.
The range to s target using the fixed range rings is determinedby eounting
the number of rings between the center of the CRT and the target. Check
the fixed range ring interval (this value appears at the second top left
corner of the CRT) and judge the distance of the echo from the inner edge
of the nearest ring. For example, the 12nm range scale has six fixed range
rings, each at a 2nm interval. Therefore if a target is positioned close to
the 5th ring from the center of the display, the range to the target would
bc lOnm.
To obtain a more accurate reading of the distance to a target the cursor
or the VRM and the cursor should be used. Now try measuring the range
of the same target pip with the cursor and the VRM in this order. Using
the trackbali, loeate the intersection of the cursor on the inside edge of the
pip. Now you can read the range at the first lower center of the screen.
Next. press the tuuchpaU. The VRM is presenled on the screen as a
dashed ring so as to distinguish it from the fixed range rings, and its
range is shown at the lower right-hand side of the screen.
The range to the cursor varies with trackbali operation, while the VRM and
its indicator reraain on the screen until the VRM is reset.
Range in Use
Fixed Range Ring
Interval
Target Pip
Fig.26 Range MeaSUrement with
the Fixed Range Rings
Variable Range
Marker (VF3V1)
Range to Cursor
VHVI Indicator
Range to VHVi
Fig.27 Range Measurement with
the Cursor and the VHvi
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