DIN EN 300392-11-21-2003 地面无线中继线路(TETRA).声音加数据(V+D).第11部分:补充业务阶段2.第21分部分:环境监听(AL)
Terrestrial Trunked Radio (TETRA) - Voice plus Data (V+D) - Part 11: Supplementary services stage 2; Sub-part 21: Ambience Listening (AL) (Endorsement of the English version EN 300392-11-21 V 1.1.1 (2003-04) as German standard)