Extra exam question E8B08
Subelement E8, SIGNALS AND EMISSIONS· Group E8B
What describes orthogonal frequency-division multiplexing (OFDM)?
- A.A frequency modulation technique that uses non-harmonically related frequencies
- B.A bandwidth compression technique using Fourier transforms
- C.A digital mode for narrow-band, slow-speed transmissions
- D.A digital modulation technique using subcarriers at frequencies chosen to avoid intersymbol interference (correct answer)
WhyOFDM is a digital modulation technique using subcarriers at frequencies chosen to avoid intersymbol interference. OFDM is a digital modulation technique that spreads data across many subcarriers, positioned at frequencies specifically chosen so they don't interfere with each other (avoiding intersymbol interference) even though they're closely spaced and technically overlap in the frequency domain, answer D. It isn't an FM technique using non-harmonic frequencies, isn't primarily a bandwidth compression method, and isn't specifically a narrow-band, slow-speed mode, OFDM's actual defining feature is that carefully chosen subcarrier spacing.
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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