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 causes precipitation (rain) clutter on a marine radar display?
Answer: Reflection of the radar signal from raindrops, snowflakes, or hail in the atmosphere between the antenna and the target
Precipitation clutter is caused by radar energy scattered back from water droplets in rain, snow, or hail, which can mask weaker target echoes behind or within the precipitation.
What is the function of FTC (Fast Time Constant) or rain clutter control in a radar receiver?
Answer: It differentiates the received signal, emphasizing sharp leading edges of echoes and reducing the effect of extended precipitation returns
FTC applies differentiation to the received video signal, highlighting the leading edges of targets while suppressing the more gradual, sustained returns from rain clutter.
What type of interference on a radar display typically appears as a series of dots or dashes in a spiral or rotating pattern?
Answer: Radar-to-radar interference from another vessel's radar operating on a similar frequency
Radar-to-radar interference from another ship's radar produces characteristic spiral, dotted, or dashed patterns that slowly rotate or change with each antenna sweep.
What is the purpose of an interference rejection (IR) control on a marine radar?
Answer: To detect and suppress pulse interference from other nearby radars by comparing consecutive sweeps and rejecting non-repeating returns
Interference rejection compares successive antenna sweeps and suppresses returns that appear only once (as other radars' pulses would), while preserving genuine echoes that appear consistently.
How does ice or heavy salt spray accumulation on a radar radome affect performance?
Answer: It can attenuate the transmitted and received signal, reducing maximum range and target detectability
Ice, snow, or heavy salt deposits on a radome introduce additional RF attenuation, reducing the energy reaching and returning from targets and degrading overall radar performance.
What is the purpose of impedance matching in a radar RF transmission line (waveguide or coaxial cable)?
Answer: To maximize power transfer and minimize reflections (VSWR) between the transmitter, transmission line, and antenna
Proper impedance matching ensures maximum RF power is transferred from transmitter to antenna with minimal reflected power, which if unmatched could damage the transmitter or reduce range.