The process of combining voice, tone, or other information with a radio signal, either as amplitude modulation (AM) or frequency modulation (FM), usually in two-way fire service radio
Ralph W. Burklin & Robert G. Purington, Fire Terms: A Guide to Their Meaning and Use, National Protection Association, Boston, MA 1980 USA. (Guide: Meaning and Use, Nat Prot Association Fr Srvc - Amer) {457}