Operation Manual

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5-16
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Display of Past Positions [PAST POSN]･････････････････････
Press the [PAST POSN] switch to display the past position of targets.
A maximum of six past positions for each target can appear. Every time the [PAST POSN]
switch is pressed, the time interval is changed between 0.5, 1, 2 and 4 minutes. When the
interval is 4 and the switch is pressed again, the past positions on display will be turned
OFF.
The interval is displayed under PAST POSN in the
ARPA information screen. When OFF is
displayed, the past position display is turned off.
The trail mode is interlocked with the vector mode
to allow the past positions of a target to appear in
the True or Relative Vector mode. In the Relative
Vector mode, the target’s relative past positions
are displayed. In the True Vector mode, the
target’s true past positions are displayed after
calculating them from its relative bearing and
range, and the course and speed of the own ship.
Fig. 5-2 shows an example of a screENTisplay,
and Table 5-1 shows the meanings of the symbols on the radar screen.
Trackball
(Cursor)
Lost target
Untracked target
NAV line
Past Positions
(Straight course)
Safe target
(Changed course)
Dangerous target
Target intruding into the guard zone
Guard zone
Past positions
HL
Fig. 5.2 Example of Display (In North Up and True Vector Mode)
In addition to the marks and symbols shown above, fixed/variable range markers, electronic
bearing lines and other symbols are shown in an actual image.