SIST EN 301 842-2 V1.1.1:2003

• Abstract:

  This EN will cover VHF aeronautical radio equipment operating at 25 kHz channel spacing in the aeronautical band 118-136.975MHz. It covers ground-based, fixed data communication, VHF Data Link (VDL) mode 4. Reference documents: EUROCAE WG51 vdl MODE 4 MOPS ICAO SARPS on VDL mode 4

• Status: Published
• Publication Date: 31-Mar-2003
• ICS: 33.060.99 - Other equipment for radiocommunications
• ICS: 33.100.01 - Electromagnetic compatibility in general
• ICS: 35.100.20 - Data link layer
• Technical Committee: RES - Radio equipment and systems
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Apr-2003
• Due Date: 01-Apr-2003
• Completion Date: 01-Apr-2003
• Mandate: M/239
• Ref Project: ETSI EN 301 842-2 V1.1.1 (2002-08) - Electromagnetic compatibility and Radio spectrum Matters (ERM); VHF air-ground Data Link (VDL) Mode 4 radio equipment; Technical characteristics and methods of measurement for ground-based equipment; Part 2: Data link layer

SIST EN 301 842-2 V1.1.1:2003 is the Slovenian adoption of ETSI EN 301 842-2 V1.1.1 for VHF air-ground Data Link (VDL) Mode 4 ground-based equipment. It specifies the data link layer for ground stations operating in the aeronautical VHF band with 25 kHz channel spacing, including the MAC behavior, reservation and broadcast procedures, LME functions, and the protocol tests used to verify them. It is intended for manufacturers, test laboratories, and certifying authorities that need interoperable ground equipment aligned with ICAO VDL Mode 4 requirements.

What does SIST EN 301 842-2 V1.1.1:2003 specify?

SIST EN 301 842-2 V1.1.1:2003 specifies the minimum performance and protocol behavior for ground-based VDL Mode 4 radio transmitters, receivers, and transceivers used for air-ground data communications. The scope is limited to ground base stations and to Gaussian-filtered Frequency Shift Keying (GFSK) systems with 25 kHz channel spacing.

The document is written around broadcast-oriented ground station operation. It does not include point-to-point communication as part of its scope, and it assumes coordinated ground stations rather than isolated ones. That matters because slot use, reservations, timing, and autotune behavior are all defined from the viewpoint of a managed ground network.

The standard is organized into the following main clauses:

• Clause 1 - Scope
• Clause 2 - References
• Clause 3 - Definitions and abbreviations
• Clause 4 - General description of VDL Mode 4 ground station link layer
• Clause 5 - Minimum performance specification under standard test conditions
• Clause 6 - General design requirements
• Clause 7 - Protocol test procedures

Annex	What it covers
Annex A	Cross reference matrix
Annex B	Description of ISO/IEC 9646 test methodology

What are the key requirements of SIST EN 301 842-2 V1.1.1:2003?

The core of SIST EN 301 842-2 V1.1.1:2003 is in Clause 5, which defines how a ground station must time, format, select, reserve, transmit, and receive VDL Mode 4 traffic. In practice, this is the part a designer or tester uses to decide whether the equipment will interoperate on the air interface.

MAC sublayer timing and transmission behavior

Clause 5.1 requires the MAC sublayer to acquire the shared communication path, accept burst and frame data from upper layers, and forward received bursts and frames upward. Transmissions shall begin only at slot boundaries, and received bursts with invalid CRC are discarded. This matters because VDL Mode 4 depends on slot-accurate behavior and clean separation between good and bad receptions.

Clause 5.1 also covers time synchronization. The ground station uses primary and secondary timing, aligns to the UTC second, and reports data quality level. For a buyer or integrator, this means the station must hold accurate timing well enough to keep the network stable and to support coordinated broadcasts.

Burst structure and station addressing

Clause 5.2 defines the VSS burst structure, including source address, message ID, information field, reservation fields, and CRC. It also limits the maximum burst length through the parameter N1. The Message ID tells the receiving station which VSS user is responsible for handling the burst, so correct encoding is critical for routing and service behavior.

Clause 5.2.5 requires a station to recognize and process all reservation types, and to discard unknown reservation types or invalid subfields. It also defines how a received burst is interpreted in time: the current slot is the slot in which the transmission begins, and burst length is measured across the occupied slots. That matters for collision handling, reservation tracking, and test repeatability.

Quality of service and slot selection

Clause 5.2.3 and Clause 5.2.4 define the VSS parameters and quality of service parameters. These include VS1 for ground quarantined slots, VS2 for minimum co-channel interference performance, VS4 for quarantine slot re-use range, and Q1 to Q4 for priority and slot selection control. In practice, these parameters govern which slots a station may use and how it balances priority against availability.

Clause 5.2.6 defines reserved access slot selection. A station builds a list of available slots from candidate slots, adds unreserved slots first, then considers previously reserved slots if needed, and selects among them according to the level rules. If no slot is available, it reports failure. For the user, this is the rule set that decides whether a requested transmission can be scheduled without conflict.

Broadcast, request, and reservation protocols

Clause 5.2 includes multiple protocol families: random access, fixed access, null reservation, periodic broadcast, incremental broadcast, combined periodic/incremental broadcast, BND broadcast, unicast request, information transfer request, directed request, block reservation, response, general request, and general response. These protocols are the operational toolbox for VDL Mode 4 ground stations.

This variety matters because different tasks need different reservation patterns. Some messages reserve one response slot, some establish repeating broadcasts, and others create future transmission blocks. The document gives the encoding and handling rules for each case so that stations can interpret each other’s reservations consistently.

Synchronization and network entry

Clause 5.3 defines LME synchronization bursts. All VDL Mode 4 stations shall transmit synchronization bursts to support link synchronization, and those bursts carry position, altitude, time figure of merit, data age, and information field identifiers. The ground station version also announces existence, position, and current time, which helps other stations derive slot structure and timing.

Clause 5.3 also covers network entry. A ground station is assumed to listen on a channel for at least one minute before operating there, and it shall recognize pleas and BND reservations from other stations. That matters in deployment because network entry is not an instantaneous connect event - the station is expected to observe the channel and join in a controlled way.

Ground-station-specific behavior and design rules

Clause 5.4 adds ground station interface and coordination requirements. The ground station is assumed to be part of a coordinated network, to support fixed transmission parameters, to protect fixed access using ground quarantine or suitable reservation protocols, and to report channel usage. It can issue and recognize autotunes, but is not required to answer autotunes from another ground station.

Clause 6 adds general design requirements. The equipment shall support controls and indicators, warm-up behavior, software management with software criticality level C, failure recovery, and monitoring of proper operation. It shall include Built-in Test Equipment (BITE) and give failure indications to local and/or remote management. That is important for maintenance planning and acceptance testing.

What terms does SIST EN 301 842-2 V1.1.1:2003 define?

• burst - A VDL Mode 4 transmission unit made up of defined fields and bracketed by flag sequences.
• slot - A fixed time interval in VDL Mode 4; each burst starts at the beginning of a slot.
• superframe - A group of slots spanning one minute.
• synchronization burst - A burst that announces at least existence and position, and for ground stations also current time.
• station - A VDL Mode 4 Specific Services capable entity, either mobile or ground, with a unique VSS address.
• Global Signalling Channel (GSC) - A worldwide channel used for communication control.
• ground quarantine - Slots reserved for ground station use only, which mobiles avoid unless directed otherwise.

Who uses SIST EN 301 842-2 V1.1.1:2003?

The standard is used by manufacturers of VHF aeronautical radio equipment, especially ground-based transmitters, receivers, and transceivers for VDL Mode 4. It is also used by test laboratories that perform type testing or conformance testing against the protocol procedures and measurement methods.

Certification and approval authorities use it to assess whether equipment matches ICAO-aligned VDL Mode 4 behavior. Ground station operators, network planners, and maintenance teams use it when they need coordinated broadcast operation, timing stability, reservation behavior, and fault monitoring in aeronautical data communications.

The document is also relevant to ADS-B-related systems and surveillance-support applications, because the synchronization bursts and test cases include position encoding, decoding, and broadcast handling.

Which standards are used with SIST EN 301 842-2 V1.1.1:2003?

Reference	What it contributes
Annex 10 to the Convention on International Civil Aviation, ICAO VDL Mode 4 Technical Manual [1]	Main ICAO VDL Mode 4 framework that this standard follows and adapts for ground stations
EUROCAE ED-108 [2]	Interim MOPS for VDL Mode 4 aircraft transceiver for ADS-B
ETSI EN 301 489-22 [3]	EMC conditions for ground-based VHF aeronautical mobile and fixed radio equipment
ISO/IEC 3309 [4]	HDLC frame structure used for frame formatting
ETSI EN 301 842-1 [5]	General description of VDL Mode 4 used as the companion part for background and related requirements
ISO/IEC 9646 [8]	Formal test-suite methodology used for the protocol test procedures

What does the SIST EN 301 842-2 V1.1.1:2003 document contain?

The document contains detailed burst formats, parameter tables, and procedure definitions for MAC, VSS, and LME behavior. It also includes slot-selection rules, reservation handling, broadcast protocols, request/response formats, and ground-station timing and coordination requirements.

Clause 7 adds a test environment description, required test rig elements, and a formal protocol test-suite structure. The test cases cover topics such as slot selection, random access, periodic and incremental reservation, response handling, ADS report reception, and CPR encode/decode.

Annex A provides a cross reference matrix, which is useful when mapping test cases back to requirements. Annex B explains the ISO/IEC 9646-based test methodology used to express the protocol tests in a formal way.

SLOVENSKI STANDARD
01-april-2003
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Electromagnetic compatibility and Radio spectrum Matters (ERM); VHF air-ground Data
Link (VDL) Mode 4 radio equipment; Technical characteristics and methods of
measurement for ground-based equipment; Part 2: Data link layer
Ta slovenski standard je istoveten z: EN 301 842-2 Version 1.1.1
ICS:
33.060.99 Druga oprema za radijske Other equipment for
komunikacije radiocommunications
33.100.01 Elektromagnetna združljivost Electromagnetic compatibility
na splošno in general
35.100.20 Podatkovni povezovalni sloj Data link layer
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

European Standard (Telecommunications series)

Electromagnetic compatibility
and Radio spectrum Matters (ERM);
VHF air-ground Data Link (VDL)
Mode 4 radio equipment;
Technical characteristics and
methods of measurement
for ground-based equipment;
Part 2: Data link layer
2 ETSI EN 301 842-2 V1.1.1 (2002-08)

Reference
DEN/ERM-RP05-016-2
Keywords
aeronautical, radio, testing, VHF, digital
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ETSI
3 ETSI EN 301 842-2 V1.1.1 (2002-08)
Contents
Intellectual Property Rights.7
Foreword.7
Introduction .8
1 Scope.9
2 References.10
3 Definitions and abbreviations.11
3.1 Definitions.11
3.1.1 Basic reference model definitions.11
3.1.2 Service conventions definitions .11
3.1.3 General definitions.11
3.2 Abbreviations.14
4 General description of VDL Mode 4 ground station link layer.15
4.1 General.15
4.2 Ground quarantine.15
4.3 System timing.15
4.4 Net entry.16
4.5 Autotune capability.16
4.6 Autonomous and fixed access .16
5 Minimum performance specification under standard test conditions.16
5.1 MAC sublayer.16
5.1.1 Services.16
5.1.2 MAC sublayer services.17
5.1.3 MAC sublayer parameters .17
5.1.3.1 Void.17
5.1.3.2 Parameter M1 (number of slots per superframe).17
5.1.4 Time synchronization.17
5.1.4.1 Primary.17
5.1.4.2 Secondary.18
5.1.4.3 Alignment to UTC second .18
5.1.4.4 Data quality level.18
5.1.5 Slot idle/busy notification.18
5.1.5.1 Slot idle detection.18
5.1.5.2 Slot busy detection .18
5.1.5.3 Slot occupied detection .19
5.1.6 Transmission processing.19
5.1.7 Received transmission processing .19
5.2 VSS sublayer.19
5.2.1 Services.19
5.2.1.1 Error detection.19
5.2.1.2 Channel congestion.19
5.2.2 Burst format.20
5.2.2.1 VSS burst structure.20
5.2.2.2 Version number.20
5.2.2.3 Source address.21
5.2.2.4 Station address encoding.21
5.2.2.5 Message ID.21
5.2.2.6 Information field.22
5.2.2.7 Reservation fields.23
5.2.2.8 TCP change flag.23
5.2.3 VSS sublayer parameters .23
5.2.3.1 Void.24
5.2.3.2 Parameter VS1 (number of ground quarantined slots) .24
5.2.3.3 Parameter VS2 (minimum CCI performance).25
ETSI
4 ETSI EN 301 842-2 V1.1.1 (2002-08)
5.2.3.4 Parameter VS4 (quarantine slot re-use range).25
5.2.4 VSS quality of service parameters.25
5.2.4.1 Void.25
5.2.4.2 Parameter Q1 (priority) .25
5.2.4.3 Parameters Q2a to Q2d (slot selection range constraint for level n) .26
5.2.4.4 Parameter Q3 (replace queued data) .26
5.2.4.5 Parameter Q4 (number of available slots).27
5.2.5 Received transmission processing .27
5.2.6 Reserved access protocol specification.28
5.2.6.1 Reservation table.28
5.2.6.2 Selecting slots for transmission or reservation.28
5.2.6.3 Reserved transmissions.30
5.2.6.4 Reservation conflicts.31
5.2.7 Random access protocol specification .32
5.2.7.1 Void.32
5.2.7.2 Random access parameters.32
5.2.7.3 Random access procedures.33
5.2.8 Fixed access protocol specification .34
5.2.8.1 Void.34
5.2.8.2 Recommendation.34
5.2.9 Null reservation protocol specification.34
5.2.9.1 Null reservation burst format .34
5.2.10 Periodic broadcast protocol specification .35
5.2.10.1 Periodic broadcast reservation burst format.35
5.2.10.2 Periodic broadcast timers.35
5.2.10.3 Periodic broadcast parameters.36
5.2.10.4 Periodic broadcast reception procedures.36
5.2.10.5 Periodic broadcast transmission procedures.38
5.2.11 Incremental broadcast protocol specification .40
5.2.11.1 Incremental broadcast reservation burst format .40
5.2.11.2 Incremental broadcast parameters.41
5.2.11.3 Incremental broadcast reception procedures .42
5.2.11.4 Incremental broadcast transmission procedures.42
5.2.12 Combined periodic broadcast and incremental broadcast protocol specification .42
5.2.12.1 Combined periodic broadcast and incremental broadcast reservation burst.42
5.2.13 Big negative dither (BND) broadcast protocol specifications .43
5.2.13.1 BND reservation burst format.43
5.2.13.2 BND broadcast parameters.44
5.2.13.3 BND broadcast reception procedures.44
5.2.14 Unicast request protocol specification .44
5.2.14.1 Unicast request reservation burst format.44
5.2.14.2 Unicast request reception procedures.45
5.2.15 Information transfer request protocol specification .45
5.2.15.1 Information transfer request reservation burst format.45
5.2.15.2 Information transfer request reception procedures.47
5.2.16 Directed request protocol specification.47
5.2.16.1 Directed request reservation burst format .47
5.2.16.2 Directed request parameters.51
5.2.16.3 Directed request reception procedures .51
5.2.16.4 Directed request transmission procedures.52
5.2.17 Block reservation protocols specification.53
5.2.17.1 Superframe block reservation burst format .53
5.2.17.2 Second frame block reservation burst format.54
5.2.17.3 Superframe block reservation parameters .55
5.2.17.4 Superframe block reservation reception procedures .56
5.2.17.5 Second frame block reservation parameters.58
5.2.17.6 Second frame block reservation reception procedures.58
5.2.17.7 Superframe block reservation transmission procedures .59
5.2.17.8 Second frame block reservation transmission procedures.60
5.2.18 Response protocol specification .60
5.2.18.1 Response burst format.60
5.2.19 General request protocol specification.61
ETSI
5 ETSI EN 301 842-2 V1.1.1 (2002-08)
5.2.19.1 General request burst format.61
5.2.19.2 General request procedures .62
5.2.20 General response protocol specification .62
5.2.20.1 General response burst format.62
5.2.20.2 General response procedures.64
5.3 Link Management Entity sublayer .64
5.3.1 Services.64
5.3.2 Synchronization burst format.64
5.3.2.1 Void.64
5.3.2.2 Fixed and variable data fields.64
5.3.2.3 Fixed data field format .65
5.3.2.4 Variable data field format .68
5.3.2.5 Synchronization burst request .68
5.3.2.6 XID burst.69
5.3.3 Exchange identity (XID) parameter formats.69
5.3.4 LME procedures.74
5.3.4.1 Synchronization burst procedures .74
5.3.4.2 Network entry protocol specifications .76
5.4 Additional requirements for ground stations .77
5.4.1 System timing requirements .77
5.4.1.1 Maintenance of Primary time.77
5.4.2 Ground station interface requirements.77
5.4.2.1 Ground station coordination.77
5.4.2.2 Fixed transmission parameters .78
5.4.2.3 Protection of fixed access protocol transmissions by ground quarantine.78
5.4.2.4 Protection of fixed access protocol transmissions by use of appropriate reservation protocols.78
5.4.2.5 Restriction of autotune reservations.79
5.4.2.6 Transmission time for autotune reservations.79
5.4.2.7 Reporting of channel usage.79
6 General design requirements.80
6.1 Controls and indicators.80
6.2 Operation of controls.80
6.3 Warm up.80
6.4 Effects of tests .80
6.5 Software management.80
6.6 Recovery from failure .80
6.6.1 Failure of the VDL equipment.80
6.7 Monitoring of proper operation .80
7 Protocol test procedures.81
7.1 General.81
7.1.1 Input voltage.81
7.1.2 Power input frequency.81
7.1.3 Adjustment of equipment.81
7.1.4 Equipment configuration.81
7.1.5 Test equipment.81
7.1.6 Test equipment precautions .82
7.1.7 Ambient conditions.82
7.1.8 Connected loads.82
7.1.9 Warm-up period.82
7.2 Required test rig .82
7.3 Protocol test-suite description methodology .84
7.4 Detailed protocol test procedures .85
7.4.1 Test-suite overview.85
7.4.2 Declarations.89
7.4.3 Constraints.89
7.4.3.1 Abbreviations.89
7.4.3.1.1 Subfield mnemonics.89
7.4.3.1.2 Special characters used in the subfield definitions .90
7.4.3.1.3 Station addresses and positions .90
7.4.3.1.4 VDL bursts and frames.91
ETSI
6 ETSI EN 301 842-2 V1.1.1 (2002-08)
7.4.3.2 Test cases.113
7.4.3.2.1 Test case macros.114
7.4.3.2.2 Test case descriptions .115
Annex A (informative): Cross reference matrix.270
Annex B (informative): Description of ISO 9646 Test Methodology.282
B.1 Overview of the Structure of the ISO 9646 Test-Suites.282
B.2 The Test Case Description .282
B.3 The Queue Action .284
B.4 The Repeat Construct .284
B.5 Macro Definitions.285
B.6 Test Case Naming .285
History .288

ETSI
7 ETSI EN 301 842-2 V1.1.1 (2002-08)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://webapp.etsi.org/IPR/home.asp).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This European Standard (Telecommunications series) has been produced by ETSI Technical Committee
Electromagnetic compatibility and Radio spectrum Matters (ERM).
The present document is part 2 of a multi-part deliverable covering the VHF air-ground Data Link (VDL) Mode 4 radio
equipment; Technical characteristics and methods of measurement for ground-based equipment, as identified below:
Part 1: "General description and physical layer";
Part 2: "Data link layer";
Part 3: "Additional broadcast aspects";
Part 4: "Point-to-point functions".

National transposition dates
Date of adoption of this EN: 2 August 2002
Date of latest announcement of this EN (doa): 30 November 2002
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 31 May 2003
Date of withdrawal of any conflicting National Standard (dow): 31 May 2003

ETSI
8 ETSI EN 301 842-2 V1.1.1 (2002-08)
Introduction
The present document states the technical specifications for Very High Frequency (VHF) Digital Link (VDL) Mode 4
ground-based radio transmitters, transceivers and receivers for air-ground communications operating in the VHF band
(117,975 MHz to 136,975 MHz), using Gaussian-filtered Frequency Shift Keying (GFSK) Modulation with 25 kHz
channel spacing. Optionally, the transmitters, transceivers and receivers may tune between 113 MHz to 117,975 MHz.
The present document may be used to produce tests for the assessment of the performance of the equipment. The
performance of the equipment submitted for type testing should be representative of the performance of the
corresponding production model.
The present document has been written on the assumption that:
• the type test measurements will be performed only once, in an accredited test laboratory and the measurements
accepted by the various authorities in order to grant type approval;
• if equipment available on the market is required to be checked it will be tested in accordance with the methods of
measurement specified in the present document or a documented alternative approved by the certifying
authority;
• Equipment comply with EN 301 489-22 [3].
ETSI
9 ETSI EN 301 842-2 V1.1.1 (2002-08)
1 Scope
The present document states the minimum performance requirements for radio transmitters, receivers and transceivers
for ground-based VHF Datalink mode 4 (VDL mode 4) equipment intended to be used for air-ground data
communications, operating in the VHF band (117,95 MHz to 137 MHz and optionally 113 MHz to 117,95 MHz)
allocated to the aeronautical mobile service. It 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) and VDL Mode 4
Technical Manual (TM) [1].
Manufacturers should note that in the future, all or part of the frequency band 108,000 MHz to 117,975 MHz might
become available for aeronautical communications.
The present document applies to Gaussian-filtered Frequency Shift Keying (GFSK) systems, with channel separations
of 25 kHz intended for air-ground communications. The scope of the present document is limited to ground base
stations.
The VDL system provides data communication exchanges between aircraft and ground based systems supporting
surveillance applications. The supported modes of communication include:
• broadcast and point-to-point communication;
• air-air and ground-air;
• operation without ground infrastructure.
VDL Mode 4 is designed to be an Air/Ground subsystem of the Aeronautical Telecommunication Network (ATN)
using the AM(R)S band and it is organized according to the Open Systems Interconnection (OSI) model (defined by
ISO). It provides reliable sub network services to the ATN system.
The present document specifies functional specifications of radio transmitters, receivers and transceivers at
ground-based VHF communication equipment intended to be used for air-ground and air-air data communications. The
present document is derived from the specifications:
• Mode 4 standards produced under the auspices of the International Civil Aviation Organization (ICAO) [1].
• Other relevant standards as defined in clause 2.
EN 301 842-1 [5] deals with tests of the physical layer. The present document deals with tests of the link layer
sufficient to support broadcast functionality. The present document also includes requirements and tests sufficient to
recognize and respond to transmissions associated with point-to-point communication. Detailed requirements for
point-to-point communication are beyond the scope of the present document.
The present document includes:
• references, definitions, abbreviations and symbols are provided in clauses 2 and 3;
• clause 4 describes the VDL Mode 4 ground station link layer;
• clause 5 performance specifications for the VDL Mode 4 ground station;
• clause 6 provides general design requirements;
• clause 7 provide protocol tests which emphasis the ADS-B functions of the system;
• a document history is contained in clause 8;
• clause A provides a detailed cross-reference to the relevant requirements contained in reference [1];
• annex B provides a description of the ISO/IEC 9646 [8] Test Methodology.
ETSI
10 ETSI EN 301 842-2 V1.1.1 (2002-08)
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 ADS-B 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. Therefore:
• a detailed set of protocol tests are provided for the broadcast functionality necessary to support ADS-B
functions;
• a detailed test of position encoding and decoding is provided because of the importance of position in the
management of the VDL Mode 4 link specifically and the need to support ADS-B applications in general.
Mandating and Recommendation Phrases
a) "Shall":
the use of the word "Shall" indicates a mandated criterion; i.e. compliance with the particular procedure or
specification is mandatory and no alternative may be applied.
b) "Should":
the use of the word "Should" (and phrases such as "It is recommended that.", etc.) indicates that though the
procedure or criterion is regarded as the preferred option, alternative procedures, specifications or criteria
may be applied, provided that the manufacturer, installer or tester can provide information or data to
adequately support and justify the alternative.
2 References
The following documents contain provisions which, through reference in this text, constitute provisions of the present
document.
• References are either specific (identified by date of publication and/or edition number or version number) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• For a non-specific reference, the latest version applies.
[1] Annex 10 to the Convention on International Civil Aviation, International Civil Aviation
Organization (VDL Mode 4 Technical Manual).
[2] EUROCAE ED-108: "Interim MOPS for VDL Mode 4 Aircraft Transceiver for ADS-B".
[3] ETSI EN 301 489-22: "Electromagnetic compatibility and Radio spectrum Matters (ERM);
ElectroMagnetic Compatibility (EMC) standard for radio equipment and services; Part 22:
Specific conditions for ground based VHF aeronautical mobile and fixed radio equipment".
[4] ISO/IEC 3309 (1993): "Information technology - Telecommunications and information exchange
between systems - High-level data link control (HDLC) procedures - Frame structure".
[5] ETSI EN 301 842-1 (V1.1.1): "Electromagnetic compatibility and Radio spectrum Matters (ERM);
VHF air-ground Data Link (VDL) Mode 4 radio equipment; Technical characteristics and methods
of measurement for ground-based equipment; Part 1: General description and physical layer".
[6] ISO/IEC 7498-1 (1994): "Information technology - Open Systems Interconnection - Basic
Reference Model: The Basic Model".
[7] ISO/IEC 10731 (1994): "Information technology - Open Systems Interconnection - Basic
Reference Model - Conventions for the definition of OSI services".
[8] ISO/IEC 9646: "Information technology - Open Systems Interconnection - Conformance testing
methodology and framework".
[9] ED-14D/DO-160D: "Environmental conditions and Test Procedures for Airborne Equipment".
ETSI
11 ETSI EN 301 842-2 V1.1.1 (2002-08)
3 Definitions and abbreviations
3.1 Definitions
3.1.1 Basic reference model definitions
The present document is based on the concepts developed in the open systems interconnect basic reference model and
makes use of the following terms defined in ISO/IEC 7498-1 [6]:
• layer;
• sublayer;
• entity;
• service;
• physical layer;
• data link layer.
3.1.2 Service conventions definitions
For the purposes of the present document, the terms and definitions given in ISO/IEC 10731 [7] apply:
• service provider;
• request;
• indication;
• confirm.
3.1.3 General definitions
For the purposes of the present document, the following terms and definitions apply:
aeronautical mobile service: mobile service between aeronautical stations and aircraft stations, or between aircraft
stations, in which survival craft stations may participate
Aeronautical Telecommunications Network (ATN): internetwork architecture that allows ground, air/ground, and
aircraft data sub networks to interoperate by adopting common interface services and protocols based on the
International Organization for Standardization Open Systems Interconnection Reference Model
aircraft address: unique combination of 24 bits available for assignment to an aircraft for the purpose of air-ground
communications, navigation and surveillance
NOTE: An aircraft may choose not to use this unique address and can use instead a non-unique address.
Automatic Dependent Surveillance-Broadcast (ADS-B): surveillance application transmitting parameters, such as
position, track and ground speed, via a broadcast mode data link for use by any air and/or ground users requiring it
NOTE: ADS-B is a surveillance service based on aircraft self-determination of position/velocity/time and
automatic, periodic or random, broadcast of this information along with auxiliary data such as aircraft
identity (ID), communications control parameters, etc. ADS-B is intended to support multiple high-level
applications and associated services such as cockpit display of traffic information, traffic alert and
collision avoidance functionality, enhanced traffic management in the air and on the ground, search and
rescue support and others.
autotune function: function, performed by the Link Management Entity, which allows a ground VDL Mode 4 station
to command
...