Chapter 3: Standard Radar Operations - Raytheon R80 Owner's Handbook Manual

Chapter 3: Standard Radar Operations

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Symptoms of such conditions are that acquisition is difficult and the
MARPA vectors are unstable; the symbol wanders away from the target,
locks onto another target or changes to a lost target symbol. If any of these
conditions are present, acquisition and tracking may need to be re-initiated
or, in some cases be impossible to maintain.
Risk Assessment
Each target is monitored to see if it will be within a certain distance from your
own vessel within a certain time. If so, the target is designated as dangerous and
you are warned with an audible alarm in addition to a warning on the screen.
The target symbol changes and flashes to indicate that it is a dangerous target.
Pressing any key silences the alarm and removes the warning, but the target
symbol remains dangerous.
Both the distance (Own Vessel Safe Zone) and the time (Time to Safe Zone) are
selectable as described in Section 7.5 MARPA Set Up.
If a target is lost, either because the MARPA software has lost contact with it, or
because it has moved out of range, you are warned, again with an audible alarm
and an on-screen warning. Pressing any key silences the alarm, removes the
warning and removes the lost target symbol from the screen.
Target Data
All MARPA targets are stored in a MARPA database list, which shows
bearing, range, course and speed of each tracked target.
For any one target a pop-up data box can be placed on the screen, this shows
bearing, range, course, speed, CPA (Closest Point of Approach) and TCPA
(Time to Closest Point of Approach). The target for which data is displayed is
indicated by a circle around its symbol.
Each target is displayed as a symbol to indicate its status:
Target is being acquired
Target is safe
Target is dangerous.
Target is Lost
The dangerous and lost symbols are shown flashing.
Target Vector and History
The MARPA targets can be displayed with a vector line showing where they
will be at a certain time in the future, (assuming present course and speed). You
can select a relative or true vector and the vector length .
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