scope:

The present document applies to the following radio equipment types:

1) 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).

ETSI EN 301 842-1 [4] deals with tests of the physical layer, ETSI EN 301 842-2 [5] deals with core link layer functionality and ETSI EN 301 842-3 [6] with additional broadcast functionality. The present document deals with tests of the datalink service (DLS) layer and the link layer sufficient to support point-to-point functionality.

The present document is organized as follows:

• clause 2 provides references to relevant documents;
• clause 3 provides general definitions, abbreviations and symbols used;
• clause 4 describes the VDL Mode 4 ground station point-to-point functions;
• clause 5 provides performance specifications for the VDL Mode 4 ground station;
• clause 6 provides general design requirements;
• clause 7 provides protocol tests for the point-to-point functions of the system;
• annex A provides a detailed cross-reference to the relevant requirements contained in [1];
• annex B provides a Bibliography.

Note that the system can support a very wide range of functions. It is not practical to provide specific tests for all aspects of functionality. The approach used is to provide detailed tests for the core point-to-point functionality and to provide tests of those remaining requirements which, if wrongly implemented, could cause a deterioration in the service offered by other VDL Mode 4 stations.