Error Probabilities Due to Atmospheric Noise and Flat Fading in HF Ionospheric Communication Systems

Atmospheric noise and fading are major sources of error in the transmission of digital data via ionospheric reflection. Using appropriate mathematical models of the fading and atmospheric noise, this paper derives analytical expressions for the binary error rate of FSK and PSK systems. It is demonstrated that the error rate depends on the atmospheric noise in the various diversity receivers only through a single composite noise variable equal to the sum of the detected noise powers of the outputs of identical diversity receiver filters. At large SNR's and
L
th order diversity the error rate is shown to be proportional to the reciprocal of the SNR raised to the
L
th power. Simple expressions are derived showing the system degradation resulting from the presence of atmospheric rather than Gaussian noise. A comparison of theoretical and measured error rates for the AN/FGC-29 and the AN/FGC-54 shows remarkably good agreement.