Increasing the probability of transfer GMDSS broadcast messages when transmitted over HF channel in case fading

Improving the quality of communication in the Global Maritime Distress and Safety System of navigation is one of the components of the development of the Arctic zone of the Russian Federation in terms of information support. At the same time, the most difficult is to ensure communication in the A3 and A4 areas, where a communication HF channel plays a not small role. The transfer of messages over HF channel in the broadcasting mode of SITOR-B is considered. To improve probabilistic characteristics in the work, a statistical analysis of the decisions of the demodulator is carried out. It is shown that the probability density functions are “noisy”, which is associated with the non-zero probability of a bit error. Models of Rayleigh, Rice and Nakagami distributions were used for statistical analysis. It is shown that in the case of low values of the signal-to-noise ratio, which is characteristic of high latitude tracks, a Nakagami model is preferable. The symbol error rate and message error rate in a fading communication channel, as well as the probability of receiving an erroneous message are shown. The results presented in this work can significantly improve the probabilistic characteristics of the HF radiolines when transmitting messages in SITOR-B mode.