Power Systems & Interference Mitigation Flashcards
6 cards from real CMRT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Power Systems & Interference Mitigation flashcards as text
What is the typical magnetron anode voltage used in a commercial marine radar transmitter?
Answer: Several kilovolts DC (typically 2–25 kV depending on power class)
Marine radar magnetrons require several kilovolts of DC anode voltage (commonly 2–25 kV) to produce the high-power microwave pulses needed for long-range target detection.
What is the purpose of STC (Sensitivity Time Control) in a marine radar receiver?
Answer: To reduce receiver gain for close-range returns immediately after each transmitted pulse, suppressing sea clutter near the vessel
STC automatically reduces receiver sensitivity for a brief period after each pulse transmission, attenuating the strong close-range sea clutter that would otherwise obscure nearby targets.
What component in a radar power supply converts the AC mains supply to the high-voltage DC required by the magnetron?
Answer: A high-voltage transformer and rectifier assembly
A high-voltage transformer steps up the AC mains voltage, which is then rectified and filtered to produce the stable high-voltage DC needed to drive the magnetron.
What effect do significant voltage fluctuations on the ship's supply bus have on radar performance?
Answer: They can cause erratic magnetron frequency, reduced output power, and false triggering of the modulator
Supply voltage variations can destabilize the magnetron's operating point, leading to frequency drift, reduced transmitted power, and unreliable pulse timing.
What is the typical duty cycle of a marine radar transmitter operating in standard pulse mode?
Answer: Less than 0.1% — very short pulses relative to the pulse repetition interval
Marine radars transmit extremely short pulses with long listening periods between them, resulting in a duty cycle well below 0.1%, which limits average radiated power while maintaining high peak power.
What is the function of a modulator in a marine radar transmitter?
Answer: It generates the high-voltage pulse that triggers the magnetron to emit a microwave burst
The modulator produces a precisely timed, high-voltage pulse that switches the magnetron on and off, controlling the transmitted pulse width and repetition rate.