Development of Methods for Spectral Monitoring of HF Interference to Determine the Availability of Ionospheric Radio Channels

The challenge in ionospheric HF radio communication lies in the variability of the operating frequency range and the parameters of radio channels. Consequently, there's a pressing need to develop radio sensors based on software-defined radio technology to enhance communication efficiency, especially in challenging conditions characterized by variable radio channel parameters and narrowband channel interference. In the latter scenario, sensors analyze interference spectral density to identify available channels devoid of narrowband interference, typically employing a threshold method. However, existing methods for determining available channels often encounter issues due to significant spectrum irregularities, resulting in errors in availability assessment. To address this issue, this study proposes a method involving median filtering of the measured spectrum using a sliding window filter with both small and large apertures. The primary objective of this research is to devise a methodology for evaluating the availability of HF radio communication channels, accounting for their variable characteristics, including variations in spectrum trends and significant outliers in minimum values.