ETSI EN 301 842-4适用于以下无线电设备类型:甚高频（VHF）数字链路（VDL）模式4地面无线电发射机和接收机 使用高斯滤波频移键控（GFSK）在VHF频段运行的空地通信 具有25 kHz信道间隔的调制，能够从 国际民航组织甚高频数字链路（VDL）标准中定义的112000兆赫至136975兆赫，建议 实践（SARP）[7]。本文件提供了技术规范的第4部分。本文件旨在确保经认证的设备与相关国际民航组织兼容 甚高频数字链路（VDL）标准和推荐做法（SARP）[7]和VDL模式4技术手册 （TM）[1]。制造商应注意，未来地面收发器的调谐范围也可能涵盖任何25 kHz 从108000兆赫到111975兆赫的通道。本文件的范围仅限于地面站。机载电台的等效规范如下: ETSI EN 302 842[i.1]。本技术规范第2部分提供了VDL模式4系统范围的说明 （见ETSI EN 301 842-2[5]第1条）。

ETSI EN 301 842-4 applies to the following radio equipment types:Very High Frequency (VHF) Digital Link (VDL) Mode 4 ground-based radio transmitters and receivers for air-ground communications operating in the VHF band, using Gaussian-filtered Frequency Shift Keying (GFSK) Modulation with 25 kHz channel spacing and capable of tuning to any of the 25 kHz channels from 112,000 MHz to 136,975 MHz as defined in ICAO VHF Digital Link (VDL) Standards and Recommended Practices (SARPs) [7].The present document provides part 4 of the technical specifications.The present document is designed to ensure that equipment certified to it will be compatible with the relevant ICAO VHF Digital Link (VDL) Standards and Recommended Practices (SARPs) [7] and VDL Mode 4 Technical Manual (TM) [1].Manufacturers should note that in future the tuning range for the ground transceivers may also cover any 25 kHz channel from 108,000 MHz to 111,975 MHz.The scope of the present document is limited to ground stations. The equivalent specification for airborne stations is ETSI EN 302 842 [i.1].A description of the scope of the VDL Mode 4 system is provided in part 2 of these technical specifications (see ETSI EN 301 842-2 [5], clause 1).