CMRT CMRT Target Tracking & ARPA 2

Question 1

What initial data does ARPA require from its own-ship sensors to compute accurate target tracks?

Accepted Answer

Own ship's speed and heading

Answer

ARPA needs own-ship heading (from gyrocompass) and speed (from log or GPS) to resolve relative target motion into true target motion.

Question 2

How long does IMO performance standard require an ARPA to establish a steady-state track on a new target?

Accepted Answer

Within 1 minute for 10 knots and within 3 minutes for all targets

Answer

IMO standards require ARPA to display a target's predicted motion within 1 minute for targets on steady courses at up to 10 knots, and within 3 minutes for all other targets.

Question 3

A technician notices ARPA vectors consistently point in incorrect directions even though targets are correctly positioned. Which sensor is most likely faulty?

Accepted Answer

Gyrocompass heading sensor

Answer

Incorrect vector directions with correct target positions indicate a bad heading input, because the ARPA uses heading to convert relative to true bearings.

Question 4

What does 'acquisition' mean in the context of ARPA?

Accepted Answer

The process of selecting a radar return and beginning to track it

Answer

Acquisition is the process by which the ARPA selects a radar echo (manually or automatically) and initiates a tracking algorithm on it.

Question 5

In a sea-stabilized ARPA display, a target's vector shows the target moving directly toward your vessel. What does this indicate?

Accepted Answer

The target is on a collision course with zero CPA

Answer

A true vector pointing directly at own ship in sea-stabilized mode indicates the target is heading straight for you, yielding a CPA of zero.

(CMRT) Certified Marine Radar Technician Practice Test

(CMRT) Certified Marine Radar Technician Practice Test

CMRT CMRT Target Tracking & ARPA 2