What is QPSK, 8-PSK, and QAM, and when are these modulations typically used in military RF links?

• A. They are measurement units for signal strength.
• B. They are error-correcting codes used in RF links.
• C. QPSK and 8-PSK are PSK schemes for robustness; QAM combines amplitude and phase for higher data rates; selection depends on link budget, noise, and bandwidth constraints.
• D. They are all time-division multiplexing schemes used for power savings.

Answer: (C)