Distinguish coherent vs non-coherent jamming.

• A. Coherent jamming preserves phase information to correlate with the target signal; non-coherent jamming uses noise-like interference without phase matching.
• B. Coherent jamming uses noise-like interference; non-coherent uses phase-matched signals.
• C. Coherent jamming is always easily detectable; non-coherent never affects reception.
• D. Non-coherent jamming enhances target detection.

Answer: (A)

The key idea here is the phase relationship between the jammer and the target signal. Coherent jamming uses a signal that preserves a fixed phase relationship to the target carrier, so the jammer’s waveform can be correlated with the received signal. This allows the jammer to align its interference in a way that can constructively and destructively combine with the target signal, making it much easier to swamp or counterfeit what the receiver picks up. Non-coherent jamming, in contrast, generates noise-like interference without a fixed phase relationship to the target. Since there’s no stable phase to match with, the jammer can’t exploit constructive or destructive interference in the same targeted way; the interference simply raises the overall noise floor across the band.

That’s why the statement is correct: it properly distinguishes coherent jamming as phase-matched to the target for correlation, and non-coherent jamming as phase-agnostic and noise-like.

The other descriptions don’t fit. One reversal would say coherent jamming uses noise-like interference, which is not accurate. It would also contradict the idea of phase matching. Another claim suggests coherent jamming is always easy to detect and that non-coherent never affects reception, which isn’t true—coherent jamming can be covert and very effective, while non-coherent jamming can still degrade performance by raising noise levels. Finally, saying non-coherent jamming enhances target detection is simply incorrect, since adding noise-like interference generally reduces detectability.