SELCAL operates on the high frequency (HF) or very high frequency (VHF) radio frequency bands used for aircraft communications. HF radio often has extremely high levels of background noise and can be difficult or distracting to listen to for long periods of time.
SELCAL operates within the high frequency (HF) or very high frequency (VHF) spectrum, utilized for aircraft communication purposes. HF radio is frequently plagued by intense background noise, making it challenging or annoying to concentrate on for prolonged durations.