radiotelephony

Radiotelephony is the transmission of voice communications over radio waves. It enables real-time spoken conversation between people or systems separated by distance and physical barriers. The term contrasts with radiotelegraphy, which uses coded signals without voice.

Historically, radiotelephony began with amplitude modulation and later adopted frequency modulation (FM) for improved noise resistance on VHF and UHF channels. High-frequency (HF) radiotelephony uses single-sideband (SSB) to extend range, and modern systems may employ digital voice and compression techniques over conventional channels.

Applications span civil aviation and maritime communications, public safety, and amateur radio. Bands commonly used for voice include VHF and UHF for line-of-sight links, and HF for long-range over-the-horizon links. Equipment ranges from handheld transceivers to aircraft radios and shipboard systems, often employing repeaters to extend coverage.

Operation relies on international and national regulations. The ITU and national administrations assign frequencies, licenses, and call signs, and prescribe standard phraseology to reduce ambiguity. The ICAO phonetic alphabet and radiotelephony prowords such as over, out, roger, and Wilco are widely used.

Typical radiotelephony procedures emphasize clear identification, concise messages, and proper channel use. In emergencies, standardized codes such as Mayday and Pan-Pan communicate distress. Training and adherence to regulatory requirements are essential for safety and reliability in aviation, maritime, and other critical services.