Radar System Fundamentals Flashcards
7 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 7 Radar System Fundamentals flashcards as text
What is the primary purpose of the radar duplexer in a marine radar system?
Answer: Switch the antenna between transmit and receive modes to protect the receiver
The duplexer acts as a transmit/receive switch, connecting the antenna to the transmitter during transmission and to the receiver immediately after, protecting the sensitive receiver from the high-power transmit pulse.
In radar terminology, what does 'range resolution' refer to?
Answer: The ability to distinguish between two targets at the same bearing but different ranges
Range resolution is the radar's ability to display two separate targets at the same bearing as distinct returns rather than merging them into one; it is primarily determined by pulse width.
Which component in a magnetron-based radar generates the high-frequency microwave energy?
Answer: Magnetron oscillator
The magnetron is a crossed-field vacuum tube oscillator that converts DC power into microwave energy at the radar's operating frequency, typically in the X-band (9–10 GHz) for marine radars.
What effect does increasing the pulse repetition frequency (PRF) have on maximum unambiguous range?
Answer: Decreases maximum range because the listening period between pulses shortens
Higher PRF means shorter intervals between pulses, so echoes from distant targets may return after the next pulse is sent, causing range ambiguity and effectively reducing unambiguous range.
What is the function of the radar's intermediate frequency (IF) amplifier stage?
Answer: Amplify the mixed-down received signal before detection
The IF amplifier provides most of the receiver's gain and selectivity by amplifying the signal after it has been down-converted from microwave frequency to a fixed intermediate frequency.
Which type of radar scan pattern is standard for surface-search marine navigation radars?
Answer: Continuous 360° plan position indicator (PPI) scan
Marine navigation radars use a continuously rotating antenna producing a 360° PPI display, giving the navigator a complete picture of all surrounding targets.
What is 'sea clutter' on a marine radar display?
Answer: Unwanted returns from waves and wave crests near the vessel
Sea clutter (sea return) is radar energy reflected back from the rough sea surface close to the vessel, appearing as a bright, noisy area around the center of the PPI display.