Adaptive strategies for narrowband HF communication systems based on signal power and modem performance

High-frequency (HF) radio communication systems face challenges due to variable ionospheric frequency-time dispersion and concentrated anthropogenic interference. To ensure efficient long-term operation, advanced methods, algorithms, and hardware-software solutions for sensor diagnostics are essential. This paper proposes an adaptive approach to optimize narrowband HF communication by adjusting signal power and modem performance. We explore methods for characterizing ionospheric radio channels and modem performance, alongside real-time estimation of background noise and anthropogenic interference spectral power density (SPD). A novel algorithm and corresponding HF interference sensor are introduced to support these diagnostics. The proposed adaptation technique adjusts modem performance and signal power to maximize channel availability. Experimental results in urban environments demonstrate that increasing the interference detection threshold by 5 dB improves channel availability by approximately 1.3–1.4 times, while a 10 dB increase yields a 2.5-fold gain, consistent across day and night conditions. We recommend implementing this gain estimation technique in practice: maintaining constant signal power for modem performance adaptation or adjusting radiated signal power for fixed modem performance.