Which statement about non-coherent jamming is true?

• A. Coherent jamming preserves phase information to correlate with the target signal.
• B. Coherent jamming uses noise-like interference without phase matching.
• C. Non-coherent jamming preserves phase information to correlate with the target signal.
• D. Non-coherent jamming uses noise-like interference without phase matching.

Answer: (D)

Non-coherent jamming is defined by using broad, noise-like interference that has no fixed phase relationship with the target signal. This means the jammer does not try to align its phase with the carrier, so it cannot be correlated with or canceled against the target in a phase-coherent way. The result is a raised noise floor across the spectrum that degrades signal reception without relying on any phase matching.

The other statements describe coherent jamming concepts. Preserving phase information to correlate with the target signal is a hallmark of coherent jamming, which relies on a fixed phase relationship to interfere effectively. Saying that coherent jamming uses noise-like interference without phase matching contradicts its fundamental idea, since coherent methods depend on phase alignment. Likewise, claiming non-coherent jamming preserves phase information conflicts with its defining feature of having no fixed phase relationship.