To effectively disrupt a signal, a jammer must

• A. Match the target frequency
• B. Offset the target frequency
• C. Increase transmitter power
• D. Change modulation scheme

Answer: (B)

The key idea is that jamming works by injecting energy into the same spectral region as the target signal, so the receiver must contend with a higher interference level. Offsetting the jammer’s frequency places its energy near the target within the channel’s passband, creating a beating interaction in the receiver’s demodulation path. That beating turns into fluctuating interference or noise in the baseband/IF, which degrades the signal-to-noise ratio and makes symbol timing, carrier recovery, and demodulation much harder. This in-band disruption tends to be more robust to small frequency drift and receiver filtering than simply trying to drive a pure on-frequency carrier, so the overall effect on the target signal is stronger.