As Solar Cycle 25 reached its peak with severe G4 and G5 geomagnetic storms, radio enthusiasts experienced total polar blackouts and extreme ionospheric absorption on high-frequency bands.
The 100-Hz Narrow Bandwidth Advantage
Standard single-sideband (SSB) voice transmissions require a 2.4 to 3.0 kHz bandwidth. When a coronal mass ejection blankets HF frequencies with electromagnetic noise, the energy of a voice signal is smeared across thousands of Hertz. A Continuous Wave (CW) unmodulated carrier tone occupies less than 100 Hz, concentrating all output power into a surgical needle of RF energy.
“When the bands sounded like frying bacon and voice was impossible, the CW bottom-end portions of 20m and 40m were alive with crisp, audible dits and dahs.”
Human Auditory DSP: The Ultimate Filter
The human brain’s auditory cortex functions as a biological digital signal processor capable of extracting rhythmic sinusoidal tones buried up to 6 dB below the ambient atmospheric noise floor, far outperforming standard automated digital demodulators during phase distortion events.
Voice Bandwidth: 2,700 Hz | CW Bandwidth: 100 Hz | Theoretical SNR Improvement: 10 * log10(2700 / 100) = +14.3 dB improvement.