Extra exam question E4E12
Subelement E4, AMATEUR PRACTICES· Group E4E
What causes interference received as a series of carriers at regular intervals across a wide frequency range?
- A.Switch-mode power supplies (correct answer)
- B.Radar transmitters
- C.Wireless security camera transmitters
- D.Electric fences
WhyA switch-mode power supply typically causes interference received as a series of carriers at regular intervals across a wide frequency range. A switch-mode power supply's rapid, repetitive switching action generates harmonics spaced at regular intervals across a wide swath of spectrum, showing up as a series of carriers repeating at consistent frequency intervals, answer A. Radar transmitters, wireless security cameras, and electric fences each produce their own distinctive interference signatures, but a comb-like series of evenly spaced carriers across a wide range is the classic switch-mode power supply fingerprint.
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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