DIN EN 300392-12-21-2007 地面中继无线电(TETRA).声音加数据(V+D).第12部分:补充业务阶段3.第12-21分部分:环境监听(AL)
Terrestrial Trunked Radio (TETRA) - Voice plus Data (V+D) - Part 12: Supplementary services stage 3 - Sub-part 12-21: Ambience Listening (AL) (Endorsement of the English version EN 300392-12-21 V1.3.1 (2007-07) as German standard)