CMRT Power Systems & Interference Mitigation 2

Question 1

What causes precipitation (rain) clutter on a marine radar display?

Accepted Answer

Reflection of the radar signal from raindrops, snowflakes, or hail in the atmosphere between the antenna and the target

Answer

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.

Question 2

What is the function of FTC (Fast Time Constant) or rain clutter control in a radar receiver?

Accepted Answer

It differentiates the received signal, emphasizing sharp leading edges of echoes and reducing the effect of extended precipitation returns

Answer

FTC applies differentiation to the received video signal, highlighting the leading edges of targets while suppressing the more gradual, sustained returns from rain clutter.

Question 3

What type of interference on a radar display typically appears as a series of dots or dashes in a spiral or rotating pattern?

Accepted Answer

Radar-to-radar interference from another vessel's radar operating on a similar frequency

Answer

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.

Question 4

What is the purpose of an interference rejection (IR) control on a marine radar?

Accepted Answer

To detect and suppress pulse interference from other nearby radars by comparing consecutive sweeps and rejecting non-repeating returns

Answer

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.

Question 5

How does ice or heavy salt spray accumulation on a radar radome affect performance?

Accepted Answer

It can attenuate the transmitted and received signal, reducing maximum range and target detectability

Answer

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.

(CMRT) Certified Marine Radar Technician Practice Test

(CMRT) Certified Marine Radar Technician Practice Test

CMRT Power Systems & Interference Mitigation 2