Which of the following is a valid action to improve link margin in a jammed environment?

• A. Switch to a lower gain antenna
• B. Use a less robust modulation
• C. Increase transmitter power within limits
• D. Relocate to more congested frequency

Answer: (C)

In a jammed environment, the goal is to maximize the link margin—the extra signal strength the receiver has above what it needs to decode data reliably. The most direct way to boost this margin is to increase the power of the transmitted signal within allowed limits. More transmit power raises the received signal level, improving the signal-to-noise-and-interference ratio (SNR/ Eb/N0) at the receiver. That extra energy helps the receiver overcome interference and maintain a usable link, as long as you stay within regulatory and hardware constraints and avoid causing harmful interference.

Lowering the antenna gain would reduce the received power in the intended direction, making the jam relatively stronger and the margin smaller. Using a less robust modulation would typically worsen performance in the face of interference, reducing the ability to decode correctly. Relocating to a more congested frequency places you in an even noisier, more interfered environment, further shrinking the margin.