CMRT CMRT Navigation Integration & Display Systems 2 — Questions and Answers
Question 1: What is the function of the Electronic Bearing Line (EBL) on a radar display?
- Sets radar gain automatically
- Measures the bearing to a target from own ship (Correct answer)
- Filters rain clutter
- Controls antenna tilt angle
Correct answer: Measures the bearing to a target from own ship
The EBL is a rotatable line from the vessel's position used to measure the bearing of a target or landmark on the radar display.
Question 2: Which radar display feature is used to measure the distance to a target?
- Heading line
- Variable Range Marker (VRM) (Correct answer)
- Electronic Bearing Line (EBL)
- Guard zone
Correct answer: Variable Range Marker (VRM)
The Variable Range Marker (VRM) is a range ring that the operator adjusts to coincide with a target to read off the distance.
Question 3: What is a radar 'guard zone' used for?
- Blocking interference from shore stations
- Alerting the watch when a target enters a defined area around the vessel (Correct answer)
- Reducing antenna sidelobe returns
- Calibrating the display scale
Correct answer: Alerting the watch when a target enters a defined area around the vessel
A guard zone is a user-defined sector or ring that triggers an alarm when a radar return enters it, warning of potential collision hazards.
Question 4: What does TCPA stand for in ARPA radar systems?
- Total Compass Position Azimuth
- Time to Closest Point of Approach (Correct answer)
- Target Course Prediction Algorithm
- Tuning Calibration Phase Adjustment
Correct answer: Time to Closest Point of Approach
TCPA (Time to Closest Point of Approach) indicates how many minutes until a tracked target reaches its minimum distance from own ship.
Question 5: In a radar display, what is the purpose of the 'rain clutter' (FTC) control?
- Amplifies weak long-range returns
- Reduces large returns from precipitation to reveal targets within the rain (Correct answer)
- Increases antenna rotation speed
- Switches between display color palettes
Correct answer: Reduces large returns from precipitation to reveal targets within the rain
The Fast Time Constant (FTC) or rain clutter control differentiates rapid signal changes to suppress extended rain returns and reveal point targets within precipitation.
Question 6: What interface standard is commonly used to connect radar processors to VDR (Voyage Data Recorder) systems?
- RS-232 only
- NMEA 0183 or IEC 61162 (Correct answer)
- USB 3.0
- Bluetooth LE
Correct answer: NMEA 0183 or IEC 61162
NMEA 0183 and its successor IEC 61162 are the standard serial communication protocols used to interconnect bridge systems including radar and VDR.
CMRT CMRT Navigation Integration & Display Systems 2
What is the function of the Electronic Bearing Line (EBL) on a radar display?