Development of Methods for Automatic Processing of the Interference Spectrum in the HF Band for the Problem of Assessing the Availability of Radio Channels

The problem of HF radio communication in the ionosphere is characterized by the variability of the operating frequency range and channel parameters, including time-frequency dispersion and man-made interferences. Therefore, it remains topical to develop radio sensors based on software-defined radio that enhance communication efficiency in challenging conditions where radio channel parameters and narrowband interferences vary. In the latter scenario, monitors analyze the spectral density of interference and utilize the threshold method to identify available channels that are not occupied with narrowband interferences. However, existing methods for determining available channels encounter difficulties due to significant spectrum irregularities, resulting in errors in availability estimation. To address this contradiction, this paper proposes a method of median filtering with the use of a sliding filter to process the measured spectrum. The effectiveness of the method was experimentally verified through an analysis of noise spectrum in the city of Yoshkar-Ola.