ETSI EN 302 842-4适用于以下无线电设备类型:甚高频（VHF）数字链路（VDL）模式4航空移动（机载）无线电发射机， 在VHF频段运行的空地和空空通信用收发器和接收器，使用 高斯滤波频移键控（GFSK）调制，信道间隔为25kHz，能够 根据国际民航组织VDL的定义，调谐至112000 MHz至136975 MHz的任何25 kHz信道 SARP[2]。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 VDL SARPs[2]和ICAO VDL4技术手册[1]。制造商应注意，未来发射器和接收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。本文件适用于“航空移动式（机载和地面车辆，如适用）”设备 以下简称“移动”设备。 本文件的范围仅限于移动台。地面站的等效规范为 ETSI EN 301 842[i.1]。ETSI EN 302 842-2[6]第2部分第1条提供了VDL模式4系统范围的说明。ETSI EN 302 842-1[5]涉及物理层的测试，ETSI EN 302 842-2[6]涉及核心链路层 功能和ETSI EN 302 842-3[7]以及其他广播功能。本文件涉及测试 数据链路层（DLS）和链路层足以支持点- 点对点功能。请注意，如中所述 ETSI EN 302 842-2[6]，要求支持点对点功能的系统符合ETSI EN 302 842-1[5]、ETSI EN 302 842-2[6]和本文件中的规范。

ETSI EN 302 842-4 applies to the following radio equipment types:Very High Frequency (VHF) Digital Link (VDL) Mode 4 aeronautical mobile (airborne) radio transmitters, transceivers and receivers for air-ground and air-air 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 VDL SARPs [2].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 VDL SARPs [2] and ICAO VDL4 Technical Manual [1].Manufacturers should note that in future the tuning range for the transmitter and receiver may also cover any 25 kHz channel from 108,000 MHz to 111,975 MHz.The present document applies to "aeronautical mobile (airborne and as applicable also ground vehicles)" equipment which will hereinafter be referred to as "mobile" equipment.The scope of the present document is limited to mobile stations. The equivalent specification for ground stations is ETSI EN 301 842 [i.1].A description of the scope of the VDL Mode 4 system is provided in part 2 of ETSI EN 302 842-2 [6], clause 1.ETSI EN 302 842-1 [5] deals with tests of the physical layer, ETSI EN 302 842-2 [6] deals with core link layer functionality and ETSI EN 302 842-3 [7] with additional broadcast functionality. The present document deals with tests of the datalink layer (DLS) and the link layer sufficient to support point-to-point functionality. Note that, as described in ETSI EN 302 842-2 [6], a system supporting point-to-point functionality is required to conform to ETSI EN 302 842-1 [5], ETSI EN 302 842-2 [6] and the specification in the present document.