CMRT Power Systems & Interference Mitigation

Question 1

What is the typical magnetron anode voltage used in a commercial marine radar transmitter?

Accepted Answer

Several kilovolts DC (typically 2–25 kV depending on power class)

Answer

12–24 VDC

Answer

110–230 VAC only

Answer

48 VDC as used in PoE systems

Question 2

What is the purpose of STC (Sensitivity Time Control) in a marine radar receiver?

Accepted Answer

To reduce receiver gain for close-range returns immediately after each transmitted pulse, suppressing sea clutter near the vessel

Answer

To increase radar power during heavy rain

Answer

To stabilize the display brightness under varying ambient light

Answer

To synchronize the antenna rotation with the display sweep

Question 3

What component in a radar power supply converts the AC mains supply to the high-voltage DC required by the magnetron?

Accepted Answer

A high-voltage transformer and rectifier assembly

Answer

The TR limiter

Answer

The AFC discriminator circuit

Answer

The bearing encoder

Question 4

What effect do significant voltage fluctuations on the ship's supply bus have on radar performance?

Accepted Answer

They can cause erratic magnetron frequency, reduced output power, and false triggering of the modulator

Answer

They increase antenna rotation speed

Answer

They improve receiver sensitivity

Answer

They have no effect if the radar has an internal fuse

Question 5

What is the typical duty cycle of a marine radar transmitter operating in standard pulse mode?

Accepted Answer

Less than 0.1% — very short pulses relative to the pulse repetition interval

Answer

50% — equal on and off time

Answer

Nearly 100% continuous wave

Answer

Exactly 10% as mandated by IMO

Question 6

What is the function of a modulator in a marine radar transmitter?

Accepted Answer

It generates the high-voltage pulse that triggers the magnetron to emit a microwave burst

Answer

It demodulates the received echo signals

Answer

It rotates the antenna at the correct speed

Answer

It converts radar video signals to NMEA sentences