What technique minimizes the bandwidth of a PSK31 signal?
Zero-sum character encoding
Reed-Solomon character encoding
Use of sinusoidal data pulses✓الإجابة الصحيحة
Use of linear data pulses
الشرح
PSK31 shapes each symbol with a sinusoidal (raised-cosine) envelope instead of switching phase abruptly, so the amplitude falls smoothly to zero at each phase reversal and rises again. That gentle shaping is what holds the signal to roughly its 31 Hz occupied bandwidth.