Extra exam question E3A02
Subelement E3, RADIO WAVE PROPAGATION· Group E3A
What characterizes libration fading of an EME signal?
- A.A slow change in the pitch of the CW signal
- B.A fluttery, irregular fading (correct answer)
- C.A gradual loss of signal as the sun rises
- D.The returning echo is several hertz lower in frequency than the transmitted signal
WhyLibration fading is a fluttery, irregular fading pattern on an EME signal. Libration fading is a fluttery, irregular fading pattern on an EME signal caused by the moon's complex, wobbling rotation relative to Earth, which constantly shifts the relative path lengths of reflections off different parts of the lunar surface, answer B. It isn't a slow CW pitch change, isn't tied to sunrise, and doesn't describe a frequency offset in the returning echo, those are separate EME effects.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2024-2028 NCVEC Element 4 pool (public domain); the explanation above is original writing, see our methodology.
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