Anti-jamming for satellite links: Which technique is generally the most effective against intentional jamming?

Introduction / Context:
Jamming aims to raise the noise/interference floor at the receiver. Spread-spectrum techniques mitigate this by processing gain and spectral spreading, lowering the apparent interference density at the demodulator.

Given Data / Assumptions:

• Adversary can inject narrowband or partial-band interference.
• System supports spread-spectrum waveforms (DSSS or FHSS).
• Receiver implements despreading to realize processing gain.

Concept / Approach:

Spread-spectrum distributes signal power over a wider bandwidth; after despreading, the wanted signal is compressed while the jammer remains spread, yielding processing gain that improves effective SIR. Frequency hopping further avoids sustained occupancy by a jammer.

Step-by-Step Solution:

Verification / Alternative check:

Link budget analyses show processing gain = spread bandwidth / information bandwidth; even tens of dB are possible.

Why Other Options Are Wrong:

• Frequency hopping alone helps, but “spread-spectrum modulation” encompasses the broader, stronger anti-jam framework.
• “Key leverage” and “once-only key” are not standard anti-jam terms.
• Narrowband pre-emphasis does not counter broadband or swept jammers.

Common Pitfalls:

• Overlooking synchronization and key management needed for secure FH/DSSS.

Final Answer:

Spread-spectrum modulation (including DSSS/FHSS)