CMRT Navigation Integration & Display Systems Flashcards

What is the primary purpose of ARPA (Automatic Radar Plotting Aid) in marine radar systems?

Answer: To automatically track targets and predict collision risk

ARPA automatically tracks radar targets, calculating their course, speed, and closest point of approach (CPA) to assess collision risk.

In a radar overlay on an Electronic Chart Display (ECDIS), what must be synchronized between the two systems?

Answer: Position reference and heading data

Accurate radar overlay on ECDIS requires synchronized position (GPS) and heading data so radar returns align correctly with the chart.

Which display mode shows radar targets relative to the vessel's bow and rotates as the ship turns?

Answer: Head-Up

Head-Up mode displays targets relative to the ship's bow, with the top of the screen always representing the direction the vessel is heading.

What does 'sea clutter' on a radar display represent?

Answer: Returns caused by rough sea surface waves near the antenna

Sea clutter consists of radar returns from wave surfaces near the vessel, which can mask genuine targets at short range.

Which NMEA sentence is most commonly used to feed GPS position data into a marine radar system?

Answer: NMEA $GPGLL or $GPRMC

$GPGLL (geographic position) and $GPRMC (recommended minimum data) both carry latitude/longitude and are standard feeds for radar position input.

In True Motion display mode, what remains stationary on the radar screen?

Answer: Stationary land and fixed targets

In True Motion mode, stationary objects like land appear fixed on the screen while the own-ship symbol moves, reflecting actual vessel motion.