Extra exam question E3A13
Subelement E3, RADIO WAVE PROPAGATION· Group E3A
Which of these emission modes is best for auroral propagation?
- A.CW (correct answer)
- B.SSB
- C.FM
- D.RTTY
WhyCW is generally the best emission mode for auroral propagation. CW is generally the best mode for auroral propagation because the aurora's turbulent ionization badly distorts and Doppler-smears a signal, and a simple on-off keyed CW tone tends to remain readable through that distortion better than voice or data modes do, answer A. SSB voice quickly becomes garbled, FM doesn't handle the multipath and distortion well either, and RTTY's fixed-shift tones are also more vulnerable to the smearing than a single CW tone.
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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