Short-wave Adaptive Frequency Selection "study

The adaptive HF systems should have the capability of adapting to time varying channel conditions by changing the operating frequency. The efficient operation of such systems could be reached by providing real-time evaluation of propagation conditions at available frequencies, channel occupancy monitoring and automatic choice of the best frequency.The "multi- gap" and "transient-stability" feature of HF Channel had been verified by analyzing data captured in HF channel. Then an adaptive real-time frequency selection algorithm based on minimum interference was presented. The algorithm can automatically adjust the threshold of the frequency-selection depend on the channel interference, and can reflect the real-time characteristic of HF channel. So the algorithm has high accuracy of frequency selection and strong ability of anti-interference. Results of experiments and simulation proved the algorithm is accurate and feasible.The "transient" frequency prediction and selection use the real-time frequency selection technology is more accurate than the frequency prediction of short-term or long-term that basis of statistics. The selection and use of work frequency is random, have stronger anti-interference capability..