Extra exam question E8C03
Subelement E8, SIGNALS AND EMISSIONS· Group E8C
Why should the phase of a PSK signal be changed at the zero crossing of the RF signal?
- A.To minimize bandwidth (correct answer)
- B.To simplify modulation
- C.To improve carrier suppression
- D.All these choices are correct
WhyChanging a PSK signal's phase at the zero crossing of the RF signal minimizes the signal's bandwidth. Changing a PSK signal's phase right at the RF carrier's zero crossing minimizes the resulting signal's bandwidth, since a phase change made at any other point in the cycle produces an abrupt amplitude discontinuity that spreads energy across a wider bandwidth, answer A. It doesn't simplify the modulation process itself and doesn't improve carrier suppression, those aren't the actual reason zero-crossing phase transitions are used.
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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