ETSI EN 301 841-1 V1.3.1 (2010-06)
VHF air-ground Digital Link (VDL) Mode 2; Technical characteristics and methods of measurement for ground-based equipment; Part 1: Physical layer and MAC sub-layer
VHF air-ground Digital Link (VDL) Mode 2; Technical characteristics and methods of measurement for ground-based equipment; Part 1: Physical layer and MAC sub-layer
REN/AERO-00004
Digitalne povezave VHF zrak-tla, 2. način - Tehnične karakteristike in merilne metode za talno opremo - 1. del: Fizična plast in podplast MAC
Pričujoči dokument velja za VDL 2. način zrak-tla digitalnih komunikacij, ki uporabljajo diferencialno osem fazno premično šifriranje (D8PSK), namenjeno za kanalne priraste 25 kHz. VDL sistem 2. načina zagotavlja izmenjavo podatkovne komunikacije med zračnim plovilom in talnimi sistemi. Področje uporabe pričujočega dokumenta je omejeno na talne postaje. VDL sistem 2. načina je načrtovan da je zrak/tla podsistem aeronavtičnega telekomunikacijskega omrežja (ATN) ter uporablja AM(R)S pas in je organiziran v skladu z modelom povezanih odprtih sistemov (OSI) (določen z ISO). Zagotavljal bo zanesljive podomrežne storitve ATN sistemu. Pričujoč dokument zagotavlja funkcionalne specifikacije talne radijske opreme namenjene za uporabo v tla-zrak podatkovnih komunikacijah. Pričujoč dokument je izpeljan iz naslednjih dokumentov:
- VDL 2. način SARP različice 3.0. ICAO Dodatek 10, zvezek III del I [2].
- ED 92a [3]: »MOPS za VDL 2. način letalski oddajnik-sprejemnik, ki deluje v frekvenčnem razponu 118-136.975 MHz« (2003), ki določa letalski oddajnik-sprejemnik.
Pričujoči dokument je sestavljen iz dveh delov:
- prvi del zagotavlja funkcionalne specifikacije in preskusne postopke za fizično plast in MAC podplast;
- drugi del zagotavlja funkcionalne specifikacije in preskusne postopke za plasti za povezavo in podomrežni dostop.
General Information
Standards Content (Sample)
Final draft ETSI EN 301 841-1 V1.3.1 (2010-01)
European Standard (Telecommunications series)
VHF air-ground Digital Link (VDL) Mode 2;
Technical characteristics and
methods of measurement
for ground-based equipment;
Part 1: Physical layer and MAC sub-layer
2 Final draft ETSI EN 301 841-1 V1.3.1 (2010-01)
Reference
REN/AERO-00004
Keywords
aeronautical, radio, testing
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3 Final draft ETSI EN 301 841-1 V1.3.1 (2010-01)
Contents
Intellectual Property Rights . 6
Foreword . 6
Introduction . 6
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 8
3 Definitions and abbreviations . 8
3.1 Definitions . 8
3.1.1 Basic reference model definitions . 8
3.1.2 Service conventions definitions . 9
3.1.3 General definitio ns . 9
3.2 Abbreviations . 10
4 General architecture of VDL Mode 2 . 11
5 Physical layer protocols and services functional specifications . 12
5.1 Overview . 12
5.1.1 Functions . 12
5.1.2 Data reception by the receiver . 12
5.1.3 Data transmission . 12
5.2 Transmission procedure . 12
5.3 Modulation scheme . 13
5.4 Training sequence. 13
5.4.1 RF power rise time definition . 14
5.5 Physical layer Service Access Point . 14
5.6 Tuning range and channel increments . 15
6 VDL MODE 2 equipment requirements . 15
6.1 Receiver requirements . 15
6.1.1 Sensitivity . 15
6.1.2 First Adjacent Channel Rejection . 15
6.1.3 Rejection of signals within the VHF Aeronautical band . 15
6.1.4 Rejection of signals outside the VHF Aeronautical band. 16
6.1.5 Desired signal dynamic range . 16
6.1.6 Symbol rate capture range . 16
6.1.7 Frequency capture range . 16
6.1.8 Co-channel interference . 16
6.1.9 Conducted spurious emission . 17
6.1.10 In-band Intermodulation . 17
6.1.11 Cabinet radiation . 17
6.2 Transmitter requirements . 17
6.2.1 Protection of the transmitter. 18
6.2.2 Manufacturer's declared output power . 18
6.2.3 RF power rise time . 18
6.2.4 RF power release time . 18
6.2.5 Modulation rate . 18
6.2.6 Symbol constellation error . 18
6.2.7 Conducted Spurious emissions . 19
6.2.8 Adjacent channel power . 19
6.2.9 Wide-band noise . 19
6.2.10 Frequency Tolerance. 19
6.2.11 Cabinet radiation . 19
6.2.12 Load VSWR capability . 19
6.3 Transceiver timing requirements . 20
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4 Final draft ETSI EN 301 841-1 V1.3.1 (2010-01)
6.3.1 Receiver to transmitter turn-around time . 20
6.3.2 Transmitter to receiver turn-around time . 20
6.4 MAC sub-layer requirements . 20
6.4.1 MAC services . 20
6.4.1.1 Multiple Access . 20
6.4.1.2 Channel Congestion . 20
6.4.2 MAC System Parameters . 20
6.4.2.1 Timer TM1 (inter-access delay timer). 20
6.4.2.2 Timer TM2 (channel busy timer) . 20
6.4.2.3 Parameter p (persistence) . 20
6.4.2.4 Counter M1 (maximum access attempts) . 20
6.4.3 Description of MAC Layer Procedures . 20
6.4.3.1 Channel Sensing . 20
6.4.3.2 Access Attempt . 20
6.4.3.3 Signal Quality Parameter . 21
6.4.4 Services (Part of DLS) . 21
6.4.4.1 Error Detection . 21
6.4.4.2 Station Identification . 21
7 General requirements . 21
7.1 General . 21
7.2 Controls and indicators . 21
7.3 Class of emission and modulation characteristics . 22
7.4 Warm up . 22
8 Test conditions, power sources and ambient temperatures . 22
8.1 Test power source . 22
8.2 Test channels . 22
8.3 General conditions of measurement . 22
8.3.1 Receiver test signal arrangement . 22
8.3.2 Performance check . 22
8.4 Normal and extreme test conditions . 23
8.4.1 Normal test conditions . 23
8.4.1.1 Normal temperature and humidity . 23
8.4.1.2 Normal power sources . 23
8.4.1.2.1 Mains voltage and frequency . 23
8.4.1.2.2 Other power sources . 23
8.4.2 Extreme test conditions . 23
8.4.2.1 Extreme temperatures . 23
8.4.2.2 Procedure for tests at extreme temperatures . 23
8.4.2.2.1 General . 23
8.4.2.2.2 High temperature . 24
8.4.2.2.3 Low temperature . 24
8.4.2.3 Extreme values of test power sources . 24
8.4.2.4 Other power sources . 24
8.4.2.5 Performance check . 24
9 Detailed Test Procedures for the physical layer . 24
9.1 Receiver . 24
9.1.1 BER test . 24
9.1.2 Sensitivity . 26
9.1.3 First Adjacent Channel Rejection . 27
9.1.4 Rejection of signals within the VHF Aeronautical band . 27
9.1.5 Rejection of signals outside the VHF Aeronautical band. 28
9.1.6 Desired Signal dynamic range . 29
9.1.7 Symbol rate capture range . 30
9.1.8 Frequency capture range . 30
9.1.9 Co-channel interference . 31
9.1.10 Conducted spurious emission . 31
9.1.11 In-band Intermodulation . 32
9.2 Transmitter . 33
9.2.1 Manufacturer's declared output power . 33
9.2.2 RF power rise time . 33
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5 Final draft ETSI EN 301 841-1 V1.3.1 (2010-01)
9.2.3 RF power release time . 35
9.2.4 Symbol Constellation Error . 36
9.2.5 Spurious emissions . 36
9.2.6 Adjacent channel power . 37
9.2.6.1 Method of measurement for the first adjacent channel . 37
9.2.6.2 Method of measurement for the second adjacent channel . 38
9.2.6.3 Method of measurement for the fourth adjacent channel . 38
9.2.7 Wideband noise . 40
9.2.8 Protection of the transmitter. 41
9.2.8.1 Method of measurement . 41
9.2.8.2 Requirement . 41
9.2.9 Frequency Error . 41
9.2.9.1 Definition . 41
9.2.9.2 Method of measurement . 41
9.2.9.3 Limits . 41
9.2.10 Load VSWR capability . 41
9.3 Physical layer, system parameters . 42
9.3.1 Receiver to Transmitter turn-around time . 42
9.3.2 Transmitter to Receiver turn-around time . 43
9.4 MAC sub-layer . 45
9.4.1 MAC services . 45
9.4.1.1 Multiple Access . 45
9.4.1.2 Channel Congestion . 45
9.4.2 MAC System Parameters . 46
9.4.2.1 Timer TM1 (inter-access delay timer). 46
9.4.2.2 Timer TM2 (channel busy timer) . 46
9.4.2.3 Parameter p (persistence) . 47
9.4.2.4 Counter M1 (maximum access attempts) . 48
9.4.3 Description of MAC Layer Procedures . 49
9.4.3.1 Channel Sensing . 49
9.4.3.2 Access Attempt . 49
9.4.3.3 Signal Quality Parameter . 49
9.4.4 Services (Part of DLS) . 50
9.4.4.1 Error Detection . 50
9.4.4.2 Station Identification . 50
Annex A (informative): Bibliography . 52
History . 53
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6 Final draft ETSI EN 301 841-1 V1.3.1 (2010-01)
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 Aeronautics
(AERO), and is now submitted for the ETSI standards One-step Approval Procedure.
The present document is part 1 of a multi-part deliverable covering VHF air-ground Digital Link (VDL) Mode 2;
Technical characteristics and methods of measurement for ground-based equipment, as identified below:
Part 1: "Physical layer and MAC sub-layer";
Part 2: "Upper layers".
Proposed national transposition dates
Date of latest announcement of this EN (doa): 3 months after ETSI publication
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 6 months after doa
Date of withdrawal of any conflicting National Standard (dow): 6 months after doa
Introduction
The present document states the technical specifications for ground-based equipment implementing Very High
Frequency (VHF) Digital Link (VDL) Mode 2 air interface, operating in the VHF band (117,975 MHz to 137,000 MHz)
with 25 kHz channel spacing.
Manufacturers should note that in the future, all or part of the frequency band 108,000 MHz to 117,975 MHz may
become available for aeronautical communications.
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 may be tested in accordance with the methods
of measurement specified in the present document.
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7 Final draft ETSI EN 301 841-1 V1.3.1 (2010-01)
1 Scope
The present document applies to VDL Mode 2 ground-air digital communications using Differential Eight Phase Shift
Keying (D8PSK), intended for channel increments of 25 kHz. The VDL Mode 2 system provides data communication
exchanges between aircraft and ground-based systems. The scope of the present document is limited to ground-based
stations.
The VDL Mode 2 system is designed to be a Ground/Air sub-system 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 shall provide reliable subnetwork services to the ATN system.
The present document provides functional specifications for ground-based radio equipment intended to be used for
ground-air data communications. The present document is derived from the following documents:
• VDL Mode 2 SARPs version 3.0. ICAO Annex 10 Volume III part I [2].
• ED 92a [3]: "MOPS for an Airborne VDL Mode-2 Transceiver Operating in the frequency range
118-136.975 MHz" (2003), which specifies the airborne transceiver.
The present document consists of two parts:
• the first part provides functional specifications and test procedures for physical layer and MAC sub-layer;
• the second part provides functional specifications and test procedures for link and sub-network access layers.
2 References
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.
• Non-specific reference may be made only to a complete document or a part thereof and only in the following
cases:
- if it is accepted that it will be possible to use all future changes of the referenced document for the
purposes of the referring document;
- for informative references.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are indispensable for the application of the present document. For dated
references, only the edition cited applies. For non-specific references, the latest edition of the referenced document
(including any amendments) applies.
[1] ICAO Convention on International Civil Aviation: "Annex 10 - Aeronautical
Telecommunications, Volume III - Communication Systems, Part I - Digital Data Communication
Systems, Second Edition, July 2007, incorporating Amendments 70-84 (July 2007),
Amendment 84 (applicable 19/11/09). Chapter 6 - VHF Air-ground Digital Link (VDL)".
[2] ICAO Convention on International Civil Aviation: "Annex 10 - Aeronautical
Telecommunications, Volume V - Aeronautical Radio Frequency Spectrum Utilization".
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8 Final draft ETSI EN 301 841-1 V1.3.1 (2010-01)
[3] EUROCAE ED 92a (2003): "MOPS for an Airborne VDL Mode-2 Transceiver operating in the
frequency range 118-136.975 MHz".
[4] ISO/IEC 13239: "Information technology - Telecommunications and information exchange
between systems - High-level data link control (HDLC) procedures".
[5] ISO/IEC 8208: "Information technology - Data communications - X.25 Packet Layer Protocol for
Data Terminal Equipment".
[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] ETSI EN 300 113-1: "Electromagnetic compatibility and Radio spectrum Matters (ERM); Land
mobile service; Radio equipment intended for the transmission of data (and/or speech) using
constant or non-constant envelope modulation and having an antenna connector; Part 1: Technical
characteristics and methods of measurement".
[9] ICAO Document 9776/AN970 (first edition, 2001): "Manual on VHF Digital Link (VDL)
Mode 2".
2.2 Informative references
The following referenced documents are not essential to the use of the present document but they assist the user with
regard to a particular subject area. For non-specific references, the latest version of the referenced document (including
any amendments) applies.
[i.1] ETSI EN 301 841-2: "Electromagnetic compatibility and Radio spectrum Matters (ERM); VHF
air-ground Digital Link (VDL) Mode 2; Technical characteristics and methods of measurement for
ground-based equipment; Part 2: Upper layers".
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
• service access point
• service data unit
• physical layer
• data link layer
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9 Final draft ETSI EN 301 841-1 V1.3.1 (2010-01)
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
• service user
• service primitive
• request
• indication
• confirm
3.1.3 General definitions
For the purposes of the present document, the following terms and definitions apply:
adjacent channel power: amount of the modulated RF signal power transmitted outside of the assigned channel
NOTE: Adjacent channel power includes discrete spurious, signal sidebands, and noise density (including phase
noise) at the transmitter output.
adjacent channel rejection: receiver's ability to demodulate the desired signal and meet the uncorrected BER
requirement in the presence of an interfering signal in an adjacent channel
NOTE: The ratio (in dB) between the adjacent interfering signal level and the desired signal level necessary to
achieve the specified minimum uncorrected BER, is the adjacent channel rejection (ACR) ratio.
aeronautical mobile service: mobile service between aeronautical stations and aircraft stations, or between aircraft
stations, in which survival craft stations may participate
average transmitter output power: average power supplied to the antenna transmission line by a transmitter during an
interval of time sufficiently long, compared with the lowest frequency encountered in the modulation, taken under
normal operating conditions
Bit Error Rate (BER): ratio between the number of erroneous bits received and the total number of bits received
NOTE: The uncorrected BER represents the BER without the benefit of Forward Error Correction (FEC).
Co-Channel Interference (CCI): capability of a receiver to demodulate the desired signal and achieve the minimum
specified BER performance in the presence of an unwanted signal at the same assigned channel
NOTE: The ratio (in dB) between the wanted signal level and the unwanted signal level is the co-channel
interference ratio.
conducted measurements: measurements which are made using a direct rf connection to the equipment under test
data rate: VDL Mode 2 symbol rate shall be 10 500 symbols/s, with a nominal data rate of 31 500 bits/s
ground base station: aeronautical station equipment, in the aeronautical mobile service, for use with an external
antenna and intended for use at a fixed location
interleaver: creates the AVPL_TIRS sequence made from the block segmentation of the AVLC frame and the RS
encoding
NOTE: To this end one assumes the TIRS matrix made from the RS encoding of the AVLC block segmentation.
The TIRS matrix is a matrix of octets made of 255 columns and c rows.
spurious emissions: conducted rf emissions on a frequency or frequencies which are outside the necessary bandwidth
and the level of which may be reduced without affecting the corresponding transmission of information
NOTE: Spurious emissions include parasitic emissions, intermodulation products and frequency conversion
products.
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10 Final draft ETSI EN 301 841-1 V1.3.1 (2010-01)
X 25: ITU-T standard for the protocols and message formats that define the interface between a terminal and a packet
switching network
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ACR Adjacent Channel Rejection
AGC Automatic Gain Control
AM(R)S Aeronautical Mobile (Route) Service
ATN Aeronautical Telecommunication Network
AVLC Aviation VHF Link Control
AVLC_LI Aviation VHF Link Control Length Indicator
AVPL Aviation VHF Physical Layer
AVPL-Header AVPL Header and training sequence
AVPL-TBS AVPL Transmitted Bit Scrambled sequence
AVPL-THeader AVPL Transmission Header sequence
AVPL-THI AVPL Transmitted Header appended and Interleaved sequence
AVPL-TIRS AVPL Transmitted Interleaved RS encoded sequence
AVPL-TTS AVPL Transmitted Ternary Symbol sequence
AWG Arbitrary Waveform Generator
BER Bit Error Rate
CCI Co Channel Interference
CRC Cyclic Redundancy Check
CSMA Carrier Sense Multiple Access
CW Continuous Wave
D8PSK Differentially encoded 8 Phase Shift Keying
dBc Decibels relative to the carrier
dBm Decibels relative to 1 milliwatt
DLS Data Link Service
EVM Error Vector Magnitude
FCS Frame Check Sequence
FEC Forward Error Correction
FM Frequency Modulation
HDLC High-level Data Link Control
ICAO International Civil Aviation Organization
ID IDentification (identifier)
IS Intermediate System
ISO International Organization for Standardization
LME Link Management Entity
MAC Media Access Control
OSI Open Systems Interconnection
ppm parts per million
RMS Root Mean Square
RS Reed-Solomon
SAP Service Access Point
SARPS Standards And Recommended PracticeS (ICAO)
SNAcP SubNetwork Access Protocol
SQP Signal Quality Parameter
TIRS matrix Transmission Interleaver and RS encoding matrix
VDL VHF Digital Link
VHF Very High Frequency
VME VDL Management Entity
VSA Vector Signal Analyser
VSWR Voltage Standing Wave Radio
XID Exchange ID (frame)
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11 Final draft ETSI EN 301 841-1 V1.3.1 (2010-01)
4 General architecture of VDL Mode 2
The general architecture of the VHF radio equipment operating in VDL Mode 2 is depicted in figure 1. This figure
presents the different functional parts of the VDL Mode 2 equipment.
The VDL system is related to the three lower layers of the OSI model providing services described as follows:
Layer 1 (Physical layer): provides transceiver frequency control, bit exchanges over the radio media, and notification
functions. These functions are often known as radio and modulation functions. The physical layer handles information
exchanges at the lowest level and manipulates bits. The physical layer handles modulation, data encoding and includes a
forward error correction mechanism based on interleaving and Reed Solomon coding.
Layer 2 (Link Layer): is split into two sublayers and a link management entity:
• The MAC sublayer provides access to the Physical layer by a CSMA algorithm in charge of channel access.
The MAC layer controls channel access and sharing.
• The DLS sublayer is composed of the AVLC derived from the HDLC protocol (ISO/IEC 13239 [4]) whose
main functions are frame exchanges, frame processing, and error detection.
• The LME controls the link establishment and maintenance between DLS sublayers.
Layer 3: Only the lowest network sublayer of layer 3 (SNAcP) will be described in EN 301 841-2 [i.1]. It is compliant
with the subnetwork sublayer requirements defined in the ATN SARPs and conforms with the ISO/IEC 8208 [5] (or
network layer of X.25). It provides packet exchanges over a virtual circuit, error recovery, connection flow control,
packet fragmentation, and subnetwork connection management functions.
The DLS and LME part of the Layer 2 and Layer 3 are specified in EN 301 841-2 [i.1].
APPLICATION
Layer 7
LAYER
PRESENTATION
Layer 6
LAYER
SESSION LAYER
Layer 5
Layer 4
TRANSPORT LAYER
INTERNETWORK
SUBLAYER
Layer 3
SNAcP (ISO 8208)
LME DLS (AVLC)
Layer 2
MAC (CSMA)
D8PSK (31,5 kbits/s)
Layer 1
VDL MODE 2 SARPs
: ATN SARPs
Figure 1: VDL SARPS in the ATN/OSI Organization
ETSI
12 Final draft ETSI EN 301 841-1 V1.3.1 (2010-01)
5 Physical layer protocols and services functional
specifications
5.1 Overview
The ground stations shall access the physical layer operating in simplex mode.
5.1.1 Functions
The tasks of the physical layer include the following:
• to modulate and demodulate radio carriers with a bit stream of a defined instantaneous rate to create an rf link;
• to acquire and maintain bit and burst synchronization between Transmitters and Receivers;
• to transmit or receive a defined number of bits at a requested time (packet mode) and on a particular carrier
frequency;
• to add and remove a training sequence;
• to encode and decode the Forward Error Correction scheme;
• to measure received signal strength;
• to decide whether a channel is idle or busy, for the purposes of managing channel access attempts;
• to offer a notification service about the quality of link.
5.1.2 Data reception by the receiver
The receiver shall decode input signals and forward them to the higher layers for processing.
5.1.3 Data transmission
The VDL physical layer shall appropriately encode the data received from the data link layer and transmit it over the rf
channel.
5.2 Transmission procedure
To transmit a sequence of frames, a station shall insert the bit numbers and, compute the FEC, interleave, insert the
training sequence, carry out bit scrambling, and finally encode and modulate the rf signal. See figure 2.
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13 Final draft ETSI EN 301 841-1 V1.3.1 (2010-01)
AVLC frame of length AVLC_LI to be transmitted
AVLC_LI
segment into RS blocks
RS encoder
TIRS_matrix(i,j)
AVLC_LI
interleaver
AVPL_TIRS sequence
AVLC_LI
AVPL_THI sequence
Prepare
training sequence
AVPL_THeader
AVPL_TBS sequence
bit scrambler
AVPL_TTS sequence
symbol data burst to modulator(s)
symbol segmentation
Figure 2: Data burst formatting procedure
5.3 Modulation scheme
Mode 2 shall use D8PSK, using a raised cosine filter with α = 0,6 (nominal value). The information to be transmitted
shall be differentially encoded with 3 bits per symbol transmitted as changes in phase rather than absolute phase. The
data stream to be transmitted shall be divided into groups of 3 consecutive data bits, with the least significant bit first.
Zeros shall be padded to the end of the transmissions if needed for the final channel symbol.
5.4 Training sequence
Data transmission shall begin with a demodulator training sequence consisting of five segments:
• Transmitter ramp up and power stabilization (5 symbols);
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14 Final draft ETSI EN 301 841-1 V1.3.1 (2010-01)
• synchronization and ambiguity resolution (16 symbols - the "unique word");
• reserved symbol (1 symbol);
• transmission length (a single 17 bit word);
• header FEC (5 bits).
NOTE: Immediately after these segments there is an AVLC frame.
header
transmitter power synchronization and reserved transmission length
ambiguity sequence FEC
stabilization sequence
symbol (AVLC_LI)
Figure 3: AVPL-header training sequence structure
5.4.1 RF power rise time definition
The purpose o
...
European Standard (Telecommunications series)
VHF air-ground Digital Link (VDL) Mode 2;
Technical characteristics and
methods of measurement
for ground-based equipment;
Part 1: Physical layer and MAC sub-layer
2 ETSI EN 301 841-1 V1.3.1 (2010-06)
Reference
REN/AERO-00004
Keywords
aeronautical, radio, testing
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE
Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16
Siret N° 348 623 562 00017 - NAF 742 C
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° 7803/88
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© European Telecommunications Standards Institute 2010.
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ETSI
3 ETSI EN 301 841-1 V1.3.1 (2010-06)
Contents
Intellectual Property Rights . 6
Foreword . 6
Introduction . 6
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 8
3 Definitions and abbreviations . 8
3.1 Definitions . 8
3.1.1 Basic reference model definitions . 8
3.1.2 Service conventions definitions . 8
3.1.3 General definitio ns . 9
3.2 Abbreviations . 10
4 General architecture of VDL Mode 2 . 11
5 Physical layer protocols and services functional specifications . 12
5.1 Overview . 12
5.1.1 Functions . 12
5.1.2 Data reception by the receiver . 12
5.1.3 Data transmission . 12
5.2 Transmission procedure . 12
5.3 Modulation scheme . 13
5.4 Training sequence. 14
5.4.1 RF power rise time definition . 14
5.5 Physical layer Service Access Point . 15
5.6 Tuning range and channel increments . 15
6 VDL MODE 2 equipment requirements . 15
6.1 Receiver requirements . 15
6.1.1 Sensitivity . 15
6.1.2 First Adjacent Channel Rejection . 15
6.1.3 Rejection of signals within the VHF Aeronautical band . 15
6.1.4 Rejection of signals outside the VHF Aeronautical band. 16
6.1.5 Desired signal dynamic range . 16
6.1.6 Symbol rate capture range . 16
6.1.7 Frequency capture range . 16
6.1.8 Co-channel interference . 16
6.1.9 Conducted spurious emission . 17
6.1.10 In-band Intermodulation . 17
6.1.11 Cabinet radiation . 17
6.2 Transmitter requirements . 17
6.2.1 Protection of the transmitter. 18
6.2.2 Manufacturer's declared output power . 18
6.2.3 RF power rise time . 18
6.2.4 RF power release time . 18
6.2.5 Modulation rate . 18
6.2.6 Symbol constellation error . 18
6.2.7 Conducted Spurious emissions . 19
6.2.8 Adjacent channel power . 19
6.2.9 Wide-band noise . 19
6.2.10 Frequency Tolerance. 19
6.2.11 Cabinet radiation . 19
6.2.12 Load VSWR capability . 19
6.3 Transceiver timing requirements . 20
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4 ETSI EN 301 841-1 V1.3.1 (2010-06)
6.3.1 Receiver to transmitter turn-around time . 20
6.3.2 Transmitter to receiver turn-around time . 20
6.4 MAC sub-layer requirements . 20
6.4.1 MAC services . 20
6.4.1.1 Multiple Access . 20
6.4.1.2 Channel Congestion . 20
6.4.2 MAC System Parameters . 20
6.4.2.1 Timer TM1 (inter-access delay timer). 20
6.4.2.2 Timer TM2 (channel busy timer) . 20
6.4.2.3 Parameter p (persistence) . 20
6.4.2.4 Counter M1 (maximum access attempts) . 20
6.4.3 Description of MAC Layer Procedures . 20
6.4.3.1 Channel Sensing . 20
6.4.3.2 Access Attempt . 20
6.4.3.3 Signal Quality Parameter . 21
6.4.4 Services (Part of DLS) . 21
6.4.4.1 Error Detection . 21
6.4.4.2 Station Identification . 21
7 General requirements . 21
7.1 General . 21
7.2 Controls and indicators . 21
7.3 Class of emission and modulation characteristics . 22
7.4 Warm up . 22
8 Test conditions, power sources and ambient temperatures . 22
8.1 Test power source . 22
8.2 Test channels . 22
8.3 General conditions of measurement . 22
8.3.1 Receiver test signal arrangement . 22
8.3.2 Performance check . 22
8.4 Normal and extreme test conditions . 23
8.4.1 Normal test conditions . 23
8.4.1.1 Normal temperature and humidity . 23
8.4.1.2 Normal power sources . 23
8.4.1.2.1 Mains voltage and frequency . 23
8.4.1.2.2 Other power sources . 23
8.4.2 Extreme test conditions . 23
8.4.2.1 Extreme temperatures . 23
8.4.2.2 Procedure for tests at extreme temperatures . 23
8.4.2.2.1 General . 23
8.4.2.2.2 High temperature . 24
8.4.2.2.3 Low temperature . 24
8.4.2.3 Extreme values of test power sources . 24
8.4.2.4 Other power sources . 24
8.4.2.5 Performance check . 24
9 Detailed Test Procedures for the physical layer . 24
9.1 Receiver . 24
9.1.1 BER test . 24
9.1.2 Sensitivity . 26
9.1.3 First Adjacent Channel Rejection . 27
9.1.4 Rejection of signals within the VHF Aeronautical band. 27
9.1.5 Rejection of signals outside the VHF Aeronautical band . 28
9.1.6 Desired Signal dynamic range . 29
9.1.7 Symbol rate capture range . 30
9.1.8 Frequency capture range . 30
9.1.9 Co-channel interference . 31
9.1.10 Conducted spurious emission . 31
9.1.11 In-band Intermodulation . 32
9.2 Transmitter . 33
9.2.1 Manufacturer's declared output power . 33
9.2.2 RF power rise time . 33
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5 ETSI EN 301 841-1 V1.3.1 (2010-06)
9.2.3 RF power release time . 35
9.2.4 Symbol Constellation Error . 36
9.2.5 Spurious emissions . 36
9.2.6 Adjacent channel power . 37
9.2.6.1 Method of measurement for the first adjacent channel . 37
9.2.6.2 Method of measurement for the second adjacent channel . 38
9.2.6.3 Method of measurement for the fourth adjacent channel . 38
9.2.7 Wideband noise . 40
9.2.8 Protection of the transmitter. 41
9.2.8.1 Method of measurement . 41
9.2.8.2 Requirement . 41
9.2.9 Frequency Error . 41
9.2.9.1 Definition . 41
9.2.9.2 Method of measurement . 41
9.2.9.3 Limits . 41
9.2.10 Load VSWR capability . 41
9.3 Physical layer, system parameters . 42
9.3.1 Receiver to Transmitter turn-around time . 42
9.3.2 Transmitter to Receiver turn-around time . 43
9.4 MAC sub-layer . 45
9.4.1 MAC services . 45
9.4.1.1 Multiple Access . 45
9.4.1.2 Channel Congestion . 45
9.4.2 MAC System Parameters . 46
9.4.2.1 Timer TM1 (inter-access delay timer). 46
9.4.2.2 Timer TM2 (channel busy timer) . 46
9.4.2.3 Parameter p (persistence) . 47
9.4.2.4 Counter M1 (maximum access attempts) . 48
9.4.3 Description of MAC Layer Procedures . 49
9.4.3.1 Channel Sensing . 49
9.4.3.2 Access Attempt . 49
9.4.3.3 Signal Quality Parameter . 49
9.4.4 Services (Part of DLS) . 50
9.4.4.1 Error Detection . 50
9.4.4.2 Station Identification . 50
Annex A (informative): Bibliography . 52
History . 53
ETSI
6 ETSI EN 301 841-1 V1.3.1 (2010-06)
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 Aeronautics
(AERO).
The present document is part 1 of a multi-part deliverable covering VHF air-ground Digital Link (VDL) Mode 2;
Technical characteristics and methods of measurement for ground-based equipment, as identified below:
Part 1: "Physical layer and MAC sub-layer";
Part 2: "Upper layers".
National transposition dates
Date of adoption of this EN: 25 May 2010
Date of latest announcement of this EN (doa): 31 August 2010
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 28 February 2011
Date of withdrawal of any conflicting National Standard (dow): 28 February 2011
Introduction
The present document states the technical specifications for ground-based equipment implementing Very High
Frequency (VHF) Digital Link (VDL) Mode 2 air interface, operating in the VHF band (117,975 MHz to 137,000 MHz)
with 25 kHz channel spacing.
Manufacturers should note that in the future, all or part of the frequency band 108,000 MHz to 117,975 MHz may
become available for aeronautical communications.
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 may be tested in accordance with the methods
of measurement specified in the present document.
ETSI
7 ETSI EN 301 841-1 V1.3.1 (2010-06)
1 Scope
The present document applies to VDL Mode 2 ground-air digital communications using Differential Eight Phase Shift
Keying (D8PSK), intended for channel increments of 25 kHz. The VDL Mode 2 system provides data communication
exchanges between aircraft and ground-based systems. The scope of the present document is limited to ground-based
stations.
The VDL Mode 2 system is designed to be a Ground/Air sub-system 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 shall provide reliable subnetwork services to the ATN system.
The present document provides functional specifications for ground-based radio equipment intended to be used for
ground-air data communications. The present document is derived from the following documents:
• VDL Mode 2 SARPs version 3.0. ICAO Annex 10 Volume III part I [2].
• ED 92a [3]: "MOPS for an Airborne VDL Mode-2 Transceiver Operating in the frequency range
118-136.975 MHz" (2003), which specifies the airborne transceiver.
The present document consists of two parts:
• the first part provides functional specifications and test procedures for physical layer and MAC sub-layer;
• the second part provides functional specifications and test procedures for link and sub-network access layers.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
[1] ICAO Convention on International Civil Aviation: "Annex 10 - Aeronautical
Telecommunications, Volume III - Communication Systems, Part I - Digital Data Communication
Systems, Second Edition, July 2007, incorporating Amendments 70-84 (July 2007),
Amendment 84 (applicable 19/11/09). Chapter 6 - VHF Air-ground Digital Link (VDL)".
[2] ICAO Convention on International Civil Aviation: "Annex 10 - Aeronautical
Telecommunications, Volume V - Aeronautical Radio Frequency Spectrum Utilization".
[3] EUROCAE ED 92a (2003): "MOPS for an Airborne VDL Mode-2 Transceiver operating in the
frequency range 118-136.975 MHz".
[4] ISO/IEC 13239: "Information technology - Telecommunications and information exchange
between systems - High-level data link control (HDLC) procedures".
[5] ISO/IEC 8208: "Information technology - Data communications - X.25 Packet Layer Protocol for
Data Terminal Equipment".
[6] ISO/IEC 7498-1 (1994): "Information technology - Open Systems Interconnection - Basic
Reference Model: The Basic Model".
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8 ETSI EN 301 841-1 V1.3.1 (2010-06)
[7] ISO/IEC 10731 (1994): "Information technology - Open Systems Interconnection - Basic
Reference Model - Conventions for the definition of OSI services".
[8] ETSI EN 300 113-1: "Electromagnetic compatibility and Radio spectrum Matters (ERM); Land
mobile service; Radio equipment intended for the transmission of data (and/or speech) using
constant or non-constant envelope modulation and having an antenna connector; Part 1: Technical
characteristics and methods of measurement".
[9] ICAO Document 9776/AN970 (first edition, 2001): "Manual on VHF Digital Link (VDL)
Mode 2".
2.2 Informative references
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI EN 301 841-2: "Electromagnetic compatibility and Radio spectrum Matters (ERM); VHF
air-ground Digital Link (VDL) Mode 2; Technical characteristics and methods of measurement for
ground-based equipment; Part 2: Upper layers".
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;
• service access point;
• service data unit;
• 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;
• service user;
• service primitive;
• request;
• indication;
ETSI
9 ETSI EN 301 841-1 V1.3.1 (2010-06)
• confirm.
3.1.3 General definitions
For the purposes of the present document, the following terms and definitions apply:
adjacent channel power: amount of the modulated RF signal power transmitted outside of the assigned channel
NOTE: Adjacent channel power includes discrete spurious, signal sidebands, and noise density (including phase
noise) at the transmitter output.
adjacent channel rejection: receiver's ability to demodulate the desired signal and meet the uncorrected BER
requirement in the presence of an interfering signal in an adjacent channel
NOTE: The ratio (in dB) between the adjacent interfering signal level and the desired signal level necessary to
achieve the specified minimum uncorrected BER, is the adjacent channel rejection (ACR) ratio.
aeronautical mobile service: mobile service between aeronautical stations and aircraft stations, or between aircraft
stations, in which survival craft stations may participate
average transmitter output power: average power supplied to the antenna transmission line by a transmitter during an
interval of time sufficiently long, compared with the lowest frequency encountered in the modulation, taken under
normal operating conditions
Bit Error Rate (BER): ratio between the number of erroneous bits received and the total number of bits received
NOTE: The uncorrected BER represents the BER without the benefit of Forward Error Correction (FEC).
Co-Channel Interference (CCI): capability of a receiver to demodulate the desired signal and achieve the minimum
specified BER performance in the presence of an unwanted signal at the same assigned channel
NOTE: The ratio (in dB) between the wanted signal level and the unwanted signal level is the co-channel
interference ratio.
conducted measurements: measurements which are made using a direct rf connection to the equipment under test
data rate: VDL Mode 2 symbol rate shall be 10 500 symbols/s, with a nominal data rate of 31 500 bits/s
ground base station: aeronautical station equipment, in the aeronautical mobile service, for use with an external
antenna and intended for use at a fixed location
interleaver: creates the AVPL_TIRS sequence made from the block segmentation of the AVLC frame and the RS
encoding
NOTE: To this end one assumes the TIRS matrix made from the RS encoding of the AVLC block segmentation.
The TIRS matrix is a matrix of octets made of 255 columns and c rows.
spurious emissions: conducted rf emissions on a frequency or frequencies which are outside the necessary bandwidth
and the level of which may be reduced without affecting the corresponding transmission of information
NOTE: Spurious emissions include parasitic emissions, intermodulation products and frequency conversion
products.
X 25: ITU-T standard for the protocols and message formats that define the interface between a terminal and a packet
switching network
ETSI
10 ETSI EN 301 841-1 V1.3.1 (2010-06)
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ACR Adjacent Channel Rejection
AGC Automatic Gain Control
AM(R)S Aeronautical Mobile (Route) Service
ATN Aeronautical Telecommunication Network
AVLC Aviation VHF Link Control
AVLC_LI Aviation VHF Link Control Length Indicator
AVPL Aviation VHF Physical Layer
AVPL-Header AVPL Header and training sequence
AVPL-TBS AVPL Transmitted Bit Scrambled sequence
AVPL-THeader AVPL Transmission Header sequence
AVPL-THI AVPL Transmitted Header appended and Interleaved sequence
AVPL-TIRS AVPL Transmitted Interleaved RS encoded sequence
AVPL-TTS AVPL Transmitted Ternary Symbol sequence
AWG Arbitrary Waveform Generator
BER Bit Error Rate
CCI Co Channel Interference
CRC Cyclic Redundancy Check
CSMA Carrier Sense Multiple Access
CW Continuous Wave
D8PSK Differentially encoded 8 Phase Shift Keying
dBc Decibels relative to the carrier
dBm Decibels relative to 1 milliwatt
DLS Data Link Service
EVM Error Vector Magnitude
FCS Frame Check Sequence
FEC Forward Error Correction
FM Frequency Modulation
HDLC High-level Data Link Control
ICAO International Civil Aviation Organization
ID IDentification (identifier)
IS Intermediate System
ISO International Organization for Standardization
LME Link Management Entity
MAC Media Access Control
OSI Open Systems Interconnection
ppm parts per million
RMS Root Mean Square
RS Reed-Solomon
SAP Service Access Point
SARPS Standards And Recommended PracticeS (ICAO)
SNAcP SubNetwork Access Protocol
SQP Signal Quality Parameter
TIRS matrix Transmission Interleaver and RS encoding matrix
VDL VHF Digital Link
VHF Very High Frequency
VME VDL Management Entity
VSA Vector Signal Analyser
VSWR Voltage Standing Wave Radio
XID Exchange ID (frame)
ETSI
11 ETSI EN 301 841-1 V1.3.1 (2010-06)
4 General architecture of VDL Mode 2
The general architecture of the VHF radio equipment operating in VDL Mode 2 is depicted in figure 1. This figure
presents the different functional parts of the VDL Mode 2 equipment.
The VDL system is related to the three lower layers of the OSI model providing services described as follows:
Layer 1 (Physical layer): provides transceiver frequency control, bit exchanges over the radio media, and notification
functions. These functions are often known as radio and modulation functions. The physical layer handles information
exchanges at the lowest level and manipulates bits. The physical layer handles modulation, data encoding and includes a
forward error correction mechanism based on interleaving and Reed Solomon coding.
Layer 2 (Link Layer): is split into two sublayers and a link management entity:
• The MAC sublayer provides access to the Physical layer by a CSMA algorithm in charge of channel access.
The MAC layer controls channel access and sharing.
• The DLS sublayer is composed of the AVLC derived from the HDLC protocol (ISO/IEC 13239 [4]) whose
main functions are frame exchanges, frame processing, and error detection.
• The LME controls the link establishment and maintenance between DLS sublayers.
Layer 3: Only the lowest network sublayer of layer 3 (SNAcP) will be described in EN 301 841-2 [i.1]. It is compliant
with the subnetwork sublayer requirements defined in the ATN SARPs and conforms with the ISO/IEC 8208 [5] (or
network layer of X.25). It provides packet exchanges over a virtual circuit, error recovery, connection flow control,
packet fragmentation, and subnetwork connection management functions.
The DLS and LME part of the Layer 2 and Layer 3 are specified in EN 301 841-2 [i.1].
APPLICATION
Layer 7
LAYER
PRESENTATION
Layer 6
LAYER
SESSION LAYER
Layer 5
Layer 4
TRANSPORT LAYER
INTERNETWORK
SUBLAYER
Layer 3
SNAcP (ISO 8208)
LME DLS (AVLC)
Layer 2
MAC (CSMA)
D8PSK (31,5 kbits/s)
Layer 1
VDL MODE 2 SARPs
: ATN SARPs
Figure 1: VDL SARPS in the ATN/OSI Organization
ETSI
12 ETSI EN 301 841-1 V1.3.1 (2010-06)
5 Physical layer protocols and services functional
specifications
5.1 Overview
The ground stations shall access the physical layer operating in simplex mode.
5.1.1 Functions
The tasks of the physical layer include the following:
• to modulate and demodulate radio carriers with a bit stream of a defined instantaneous rate to create an rf link;
• to acquire and maintain bit and burst synchronization between Transmitters and Receivers;
• to transmit or receive a defined number of bits at a requested time (packet mode) and on a particular carrier
frequency;
• to add and remove a training sequence;
• to encode and decode the Forward Error Correction scheme;
• to measure received signal strength;
• to decide whether a channel is idle or busy, for the purposes of managing channel access attempts;
• to offer a notification service about the quality of link.
5.1.2 Data reception by the receiver
The receiver shall decode input signals and forward them to the higher layers for processing.
5.1.3 Data transmission
The VDL physical layer shall appropriately encode the data received from the data link layer and transmit it over the rf
channel.
5.2 Transmission procedure
To transmit a sequence of frames, a station shall insert the bit numbers and, compute the FEC, interleave, insert the
training sequence, carry out bit scrambling, and finally encode and modulate the rf signal. See figure 2.
ETSI
13 ETSI EN 301 841-1 V1.3.1 (2010-06)
AVLC frame of length AVLC_LI to be transmitted
AVLC_LI
segment into RS blocks
RS encoder
TIRS_matrix(i,j)
AVLC_LI
interleaver
AVPL_TIRS sequence
AVLC_LI
AVPL_THI sequence
Prepare
training sequence
AVPL_THeader
AVPL_TBS sequence
bit scrambler
AVPL_TTS sequence
symbol data burst to modulator(s)
symbol segmentation
Figure 2: Data burst formatting procedure
5.3 Modulation scheme
Mode 2 shall use D8PSK, using a raised cosine filter with α = 0,6 (nominal value). The information to be transmitted
shall be differentially encoded with 3 bits per symbol transmitted as changes in phase rather than absolute phase. The
data stream to be transmitted shall be divided into groups of 3 consecutive data bits, with the least significant bit first.
Zeros shall be padded to the end of the transmissions if needed for the final channel symbol.
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14 ETSI EN 301 841-1 V1.3.1 (2010-06)
5.4 Training sequence
Data transmission shall begin with a demodulator training sequence consisting of five segments:
• transmitter ramp up and power stabilization (5 symbols);
• synchronization and ambiguity resolution (16 symbols - the "unique word");
• reserved symbol (1 symbol);
• transmission length (a single 17 bit word);
• header FEC (5 bits).
NOTE: Immediately after these segments there is an AVLC frame.
header
transmitter power reserved transmission length
synchronization and
FEC
stabilization sequence ambiguity sequence
symbol (AVLC_LI)
Figure 3: AVPL-header training sequence structure
5.4.1 RF power rise time definition
The purpose of the first segment of the training sequence, called the ramp-up, is to provide for transmitter power
stabilization and receiver AGC settling and it shall immediately precede the first symbol of the unique word. The first
segment also provides AGC settling time for the intended receiver. The time reference point (T), for the following
specification is the centre of the first unique word symbol, a point that occurs 1/2 a symbol period after the end of the
first segment. The start of the first segment is therefore defined at time T = -5,5 symbol periods.
Mode2 Ramp up
0,7
0,6
Steady State
0,5
0,4
0,3
0,2
0,1
-9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4
T (Symbol periods)
Key
...
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.VHF air-ground Digital Link (VDL) Mode 2 - Technical characteristics and methods of measurement for ground-based equipment - Part 1: Physical layer and MAC sub-layer35.100.10Physical layer33.060.99Druga oprema za radijske komunikacijeOther equipment for radiocommunicationsICS:Ta slovenski standard je istoveten z:EN 301 841-1 Version 1.3.1SIST EN 301 841-1 V1.3.1:2010en01-oktober-2010SIST EN 301 841-1 V1.3.1:2010SLOVENSKI
STANDARD
ETSI ETSI EN 301 841-1 V1.3.1 (2010-06) 2
Reference REN/AERO-00004 Keywords aeronautical, radio, testing ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE
Tel.: +33 4 92 94 42 00
Fax: +33 4 93 65 47 16
Siret N° 348 623 562 00017 - NAF 742 C Association à but non lucratif enregistrée à la Sous-Préfecture de Grasse (06) N° 7803/88
Important notice Individual copies of the present document can be downloaded from: http://www.etsi.org The present document may be made available in more than one electronic version or in print. In any case of existing or perceived difference in contents between such versions, the reference version is the Portable Document Format (PDF). In case of dispute, the reference shall be the printing on ETSI printers of the PDF version kept on a specific network drive within ETSI Secretariat. Users of the present document should be aware that the document may be subject to revision or change of status. Information on the current status of this and other ETSI documents is available at http://portal.etsi.org/tb/status/status.asp If you find errors in the present document, please send your comment to one of the following services: http://portal.etsi.org/chaircor/ETSI_support.asp Copyright Notification No part may be reproduced except as authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 2010. All rights reserved.
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ETSI ETSI EN 301 841-1 V1.3.1 (2010-06) 3 Contents Intellectual Property Rights . 6 Foreword . 6 Introduction . 6 1 Scope . 7 2 References . 7 2.1 Normative references . 7 2.2 Informative references . 8 3 Definitions and abbreviations . 8 3.1 Definitions . 8 3.1.1 Basic reference model definitions . 8 3.1.2 Service conventions definitions . 8 3.1.3 General definitions . 9 3.2 Abbreviations . 10 4 General architecture of VDL Mode 2 . 11 5 Physical layer protocols and services functional specifications . 12 5.1 Overview . 12 5.1.1 Functions . 12 5.1.2 Data reception by the receiver . 12 5.1.3 Data transmission . 12 5.2 Transmission procedure . 12 5.3 Modulation scheme . 13 5.4 Training sequence. 14 5.4.1 RF power rise time definition . 14 5.5 Physical layer Service Access Point . 15 5.6 Tuning range and channel increments . 15 6 VDL MODE 2 equipment requirements . 15 6.1 Receiver requirements . 15 6.1.1 Sensitivity . 15 6.1.2 First Adjacent Channel Rejection . 15 6.1.3 Rejection of signals within the VHF Aeronautical band . 15 6.1.4 Rejection of signals outside the VHF Aeronautical band. 16 6.1.5 Desired signal dynamic range . 16 6.1.6 Symbol rate capture range . 16 6.1.7 Frequency capture range . 16 6.1.8 Co-channel interference . 16 6.1.9 Conducted spurious emission . 17 6.1.10 In-band Intermodulation . 17 6.1.11 Cabinet radiation . 17 6.2 Transmitter requirements . 17 6.2.1 Protection of the transmitter. 18 6.2.2 Manufacturer's declared output power . 18 6.2.3 RF power rise time . 18 6.2.4 RF power release time . 18 6.2.5 Modulation rate . 18 6.2.6 Symbol constellation error . 18 6.2.7 Conducted Spurious emissions . 19 6.2.8 Adjacent channel power . 19 6.2.9 Wide-band noise . 19 6.2.10 Frequency Tolerance. 19 6.2.11 Cabinet radiation . 19 6.2.12 Load VSWR capability . 19 6.3 Transceiver timing requirements . 20 SIST EN 301 841-1 V1.3.1:2010
ETSI ETSI EN 301 841-1 V1.3.1 (2010-06) 4 6.3.1 Receiver to transmitter turn-around time . 20 6.3.2 Transmitter to receiver turn-around time . 20 6.4 MAC sub-layer requirements . 20 6.4.1 MAC services . 20 6.4.1.1 Multiple Access . 20 6.4.1.2 Channel Congestion . 20 6.4.2 MAC System Parameters . 20 6.4.2.1 Timer TM1 (inter-access delay timer). 20 6.4.2.2 Timer TM2 (channel busy timer) . 20 6.4.2.3 Parameter p (persistence) . 20 6.4.2.4 Counter M1 (maximum access attempts) . 20 6.4.3 Description of MAC Layer Procedures . 20 6.4.3.1 Channel Sensing . 20 6.4.3.2 Access Attempt . 20 6.4.3.3 Signal Quality Parameter . 21 6.4.4 Services (Part of DLS) . 21 6.4.4.1 Error Detection . 21 6.4.4.2 Station Identification . 21 7 General requirements . 21 7.1 General . 21 7.2 Controls and indicators . 21 7.3 Class of emission and modulation characteristics . 22 7.4 Warm up . 22 8 Test conditions, power sources and ambient temperatures . 22 8.1 Test power source . 22 8.2 Test channels . 22 8.3 General conditions of measurement . 22 8.3.1 Receiver test signal arrangement . 22 8.3.2 Performance check . 22 8.4 Normal and extreme test conditions . 23 8.4.1 Normal test conditions . 23 8.4.1.1 Normal temperature and humidity . 23 8.4.1.2 Normal power sources . 23 8.4.1.2.1 Mains voltage and frequency . 23 8.4.1.2.2 Other power sources . 23 8.4.2 Extreme test conditions . 23 8.4.2.1 Extreme temperatures . 23 8.4.2.2 Procedure for tests at extreme temperatures . 23 8.4.2.2.1 General . 23 8.4.2.2.2 High temperature . 24 8.4.2.2.3 Low temperature . 24 8.4.2.3 Extreme values of test power sources . 24 8.4.2.4 Other power sources . 24 8.4.2.5 Performance check . 24 9 Detailed Test Procedures for the physical layer . 24 9.1 Receiver . 24 9.1.1 BER test . 24 9.1.2 Sensitivity . 26 9.1.3 First Adjacent Channel Rejection . 27 9.1.4 Rejection of signals within the VHF Aeronautical band. 27 9.1.5 Rejection of signals outside the VHF Aeronautical band . 28 9.1.6 Desired Signal dynamic range . 29 9.1.7 Symbol rate capture range . 30 9.1.8 Frequency capture range . 30 9.1.9 Co-channel interference . 31 9.1.10 Conducted spurious emission . 31 9.1.11 In-band Intermodulation . 32 9.2 Transmitter . 33 9.2.1 Manufacturer's declared output power . 33 9.2.2 RF power rise time . 33 SIST EN 301 841-1 V1.3.1:2010
ETSI ETSI EN 301 841-1 V1.3.1 (2010-06) 5 9.2.3 RF power release time . 35 9.2.4 Symbol Constellation Error . 36 9.2.5 Spurious emissions . 36 9.2.6 Adjacent channel power . 37 9.2.6.1 Method of measurement for the first adjacent channel . 37 9.2.6.2 Method of measurement for the second adjacent channel . 38 9.2.6.3 Method of measurement for the fourth adjacent channel . 38 9.2.7 Wideband noise . 40 9.2.8 Protection of the transmitter. 41 9.2.8.1 Method of measurement . 41 9.2.8.2 Requirement . 41 9.2.9 Frequency Error . 41 9.2.9.1 Definition . 41 9.2.9.2 Method of measurement . 41 9.2.9.3 Limits . 41 9.2.10 Load VSWR capability . 41 9.3 Physical layer, system parameters . 42 9.3.1 Receiver to Transmitter turn-around time . 42 9.3.2 Transmitter to Receiver turn-around time . 43 9.4 MAC sub-layer . 45 9.4.1 MAC services . 45 9.4.1.1 Multiple Access . 45 9.4.1.2 Channel Congestion . 45 9.4.2 MAC System Parameters . 46 9.4.2.1 Timer TM1 (inter-access delay timer). 46 9.4.2.2 Timer TM2 (channel busy timer) . 46 9.4.2.3 Parameter p (persistence) . 47 9.4.2.4 Counter M1 (maximum access attempts) . 48 9.4.3 Description of MAC Layer Procedures . 49 9.4.3.1 Channel Sensing . 49 9.4.3.2 Access Attempt . 49 9.4.3.3 Signal Quality Parameter . 49 9.4.4 Services (Part of DLS) . 50 9.4.4.1 Error Detection . 50 9.4.4.2 Station Identification . 50 Annex A (informative): Bibliography . 52 History . 53
ETSI ETSI EN 301 841-1 V1.3.1 (2010-06) 6 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 Aeronautics (AERO). The present document is part 1 of a multi-part deliverable covering VHF air-ground Digital Link (VDL) Mode 2; Technical characteristics and methods of measurement for ground-based equipment, as identified below: Part 1: "Physical layer and MAC sub-layer"; Part 2: "Upper layers".
National transposition dates Date of adoption of this EN: 25 May 2010 Date of latest announcement of this EN (doa): 31 August 2010 Date of latest publication of new National Standard or endorsement of this EN (dop/e):
28 February 2011 Date of withdrawal of any conflicting National Standard (dow): 28 February 2011
Introduction The present document states the technical specifications for ground-based equipment implementing Very High Frequency (VHF) Digital Link (VDL) Mode 2 air interface, operating in the VHF band (117,975 MHz to 137,000 MHz) with 25 kHz channel spacing. Manufacturers should note that in the future, all or part of the frequency band 108,000 MHz to 117,975 MHz may become available for aeronautical communications. 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 may be tested in accordance with the methods of measurement specified in the present document. SIST EN 301 841-1 V1.3.1:2010
ETSI ETSI EN 301 841-1 V1.3.1 (2010-06) 7 1 Scope The present document applies to VDL Mode 2 ground-air digital communications using Differential Eight Phase Shift Keying (D8PSK), intended for channel increments of 25 kHz. The VDL Mode 2 system provides data communication exchanges between aircraft and ground-based systems. The scope of the present document is limited to ground-based stations. The VDL Mode 2 system is designed to be a Ground/Air sub-system 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 shall provide reliable subnetwork services to the ATN system. The present document provides functional specifications for ground-based radio equipment intended to be used for ground-air data communications. The present document is derived from the following documents:
• VDL Mode 2 SARPs version 3.0. ICAO Annex 10 Volume III part I [2]. • ED 92a [3]: "MOPS for an Airborne VDL Mode-2 Transceiver Operating in the frequency range 118-136.975 MHz" (2003), which specifies the airborne transceiver. The present document consists of two parts: • the first part provides functional specifications and test procedures for physical layer and MAC sub-layer; • the second part provides functional specifications and test procedures for link and sub-network access layers. 2 References References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the reference document (including any amendments) applies. Referenced documents which are not found to be publicly available in the expected location might be found at http://docbox.etsi.org/Reference. NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee their long term validity. 2.1 Normative references The following referenced documents are necessary for the application of the present document. [1] ICAO Convention on International Civil Aviation: "Annex 10 - Aeronautical Telecommunications, Volume III - Communication Systems, Part I - Digital Data Communication Systems, Second Edition, July 2007, incorporating Amendments 70-84 (July 2007), Amendment 84 (applicable 19/11/09). Chapter 6 - VHF Air-ground Digital Link (VDL)". [2] ICAO Convention on International Civil Aviation: "Annex 10 - Aeronautical Telecommunications, Volume V - Aeronautical Radio Frequency Spectrum Utilization". [3] EUROCAE ED 92a (2003): "MOPS for an Airborne VDL Mode-2 Transceiver operating in the frequency range 118-136.975 MHz". [4] ISO/IEC 13239: "Information technology - Telecommunications and information exchange between systems - High-level data link control (HDLC) procedures". [5] ISO/IEC 8208: "Information technology - Data communications - X.25 Packet Layer Protocol for Data Terminal Equipment". [6] ISO/IEC 7498-1 (1994): "Information technology - Open Systems Interconnection - Basic Reference Model: The Basic Model". SIST EN 301 841-1 V1.3.1:2010
ETSI ETSI EN 301 841-1 V1.3.1 (2010-06) 8 [7] ISO/IEC 10731 (1994): "Information technology - Open Systems Interconnection - Basic Reference Model - Conventions for the definition of OSI services". [8] ETSI EN 300 113-1: "Electromagnetic compatibility and Radio spectrum Matters (ERM); Land mobile service; Radio equipment intended for the transmission of data (and/or speech) using constant or non-constant envelope modulation and having an antenna connector; Part 1: Technical characteristics and methods of measurement". [9] ICAO Document 9776/AN970 (first edition, 2001): "Manual on VHF Digital Link (VDL) Mode 2". 2.2 Informative references The following referenced documents are not necessary for the application of the present document but they assist the user with regard to a particular subject area. [i.1] ETSI EN 301 841-2: "Electromagnetic compatibility and Radio spectrum Matters (ERM); VHF air-ground Digital Link (VDL) Mode 2; Technical characteristics and methods of measurement for ground-based equipment; Part 2: Upper layers". 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; • service access point; • service data unit; • 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; • service user; • service primitive; • request; • indication; SIST EN 301 841-1 V1.3.1:2010
ETSI ETSI EN 301 841-1 V1.3.1 (2010-06) 9 • confirm. 3.1.3 General definitions For the purposes of the present document, the following terms and definitions apply: adjacent channel power: amount of the modulated RF signal power transmitted outside of the assigned channel NOTE: Adjacent channel power includes discrete spurious, signal sidebands, and noise density (including phase noise) at the transmitter output. adjacent channel rejection: receiver's ability to demodulate the desired signal and meet the uncorrected BER requirement in the presence of an interfering signal in an adjacent channel NOTE: The ratio (in dB) between the adjacent interfering signal level and the desired signal level necessary to achieve the specified minimum uncorrected BER, is the adjacent channel rejection (ACR) ratio. aeronautical mobile service: mobile service between aeronautical stations and aircraft stations, or between aircraft stations, in which survival craft stations may participate average transmitter output power: average power supplied to the antenna transmission line by a transmitter during an interval of time sufficiently long, compared with the lowest frequency encountered in the modulation, taken under normal operating conditions Bit Error Rate (BER): ratio between the number of erroneous bits received and the total number of bits received NOTE: The uncorrected BER represents the BER without the benefit of Forward Error Correction (FEC). Co-Channel Interference (CCI): capability of a receiver to demodulate the desired signal and achieve the minimum specified BER performance in the presence of an unwanted signal at the same assigned channel NOTE: The ratio (in dB) between the wanted signal level and the unwanted signal level is the co-channel interference ratio. conducted measurements: measurements which are made using a direct rf connection to the equipment under test data rate: VDL Mode 2 symbol rate shall be 10 500 symbols/s, with a nominal data rate of 31 500 bits/s ground base station: aeronautical station equipment, in the aeronautical mobile service, for use with an external antenna and intended for use at a fixed location interleaver: creates the AVPL_TIRS sequence made from the block segmentation of the AVLC frame and the RS encoding NOTE: To this end one assumes the TIRS matrix made from the RS encoding of the AVLC block segmentation. The TIRS matrix is a matrix of octets made of 255 columns and c rows. spurious emissions: conducted rf emissions on a frequency or frequencies which are outside the necessary bandwidth and the level of which may be reduced without affecting the corresponding transmission of information NOTE: Spurious emissions include parasitic emissions, intermodulation products and frequency conversion products. X 25: ITU-T standard for the protocols and message formats that define the interface between a terminal and a packet switching network SIST EN 301 841-1 V1.3.1:2010
ETSI ETSI EN 301 841-1 V1.3.1 (2010-06) 10 3.2 Abbreviations For the purposes of the present document, the following abbreviations apply: ACR Adjacent Channel Rejection AGC Automatic Gain Control AM(R)S Aeronautical Mobile (Route) Service ATN Aeronautical Telecommunication Network AVLC Aviation VHF Link Control AVLC_LI Aviation VHF Link Control Length Indicator AVPL Aviation VHF Physical Layer
AVPL-Header AVPL Header and training sequence AVPL-TBS AVPL Transmitted Bit Scrambled sequence AVPL-THeader AVPL Transmission Header sequence AVPL-THI AVPL Transmitted Header appended and Interleaved sequence AVPL-TIRS AVPL Transmitted Interleaved RS encoded sequence AVPL-TTS AVPL Transmitted Ternary Symbol sequence AWG Arbitrary Waveform Generator BER Bit Error Rate CCI Co Channel Interference CRC Cyclic Redundancy Check CSMA Carrier Sense Multiple Access CW Continuous Wave D8PSK Differentially encoded 8 Phase Shift Keying dBc Decibels relative to the carrier dBm Decibels relative to 1 milliwatt DLS Data Link Service EVM Error Vector Magnitude FCS Frame Check Sequence FEC Forward Error Correction FM Frequency Modulation HDLC High-level Data Link Control ICAO International Civil Aviation Organization ID IDentification (identifier) IS Intermediate System ISO International Organization for Standardization LME Link Management Entity MAC Media Access Control OSI Open Systems Interconnection ppm parts per million RMS Root Mean Square RS Reed-Solomon SAP Service Access Point SARPS Standards And Recommended PracticeS (ICAO) SNAcP SubNetwork Access Protocol SQP Signal Quality Parameter TIRS matrix Transmission Interleaver and RS encoding matrix VDL VHF Digital Link VHF Very High Frequency VME VDL Management Entity VSA Vector Signal Analyser VSWR Voltage Standing Wave Radio XID Exchange ID (frame) SIST EN 301 841-1 V1.3.1:2010
ETSI ETSI EN 301 841-1 V1.3.1 (2010-06) 11 4 General architecture of VDL Mode 2 The general architecture of the VHF radio equipment operating in VDL Mode 2 is depicted in figure 1. This figure presents the different functional parts of the VDL Mode 2 equipment.
The VDL system is related to the three lower layers of the OSI model providing services described as follows: Layer 1 (Physical layer): provides transceiver frequency control, bit exchanges over the radio media, and notification functions. These functions are often known as radio and modulation functions. The physical layer handles information exchanges at the lowest level and manipulates bits. The physical layer handles modulation, data encoding and includes a forward error correction mechanism based on interleaving and Reed Solomon coding. Layer 2 (Link Layer): is split into two sublayers and a link management entity: • The MAC sublayer provides access to the Physical layer by a CSMA algorithm in charge of channel access. The MAC layer controls channel access and sharing. • The DLS sublayer is composed of the AVLC derived from the HDLC protocol (ISO/IEC 13239 [4]) whose main functions are frame exchanges, frame processing, and error detection. • The LME controls the link establishment and maintenance between DLS sublayers. Layer 3: Only the lowest network sublayer of layer 3 (SNAcP) will be described in EN 301 841-2 [i.1]. It is compliant with the subnetwork sublayer requirements defined in the ATN SARPs and conforms with the ISO/IEC 8208 [5] (or network layer of X.25). It provides packet exchanges over a virtual circuit, error recovery, connection flow control, packet fragmentation, and subnetwork connection management functions. The DLS and LME part of the Layer 2 and Layer 3 are specified in EN 301 841-2 [i.1]. D8PSK (31,5 kbits/s)DLS (AVLC)MAC (CSMA)LMEINTERNETWORKSUBLAYERTRANSPORT LAYERSESSION LAYERPRESENTATIONLAYERAPPLICATIONLAYERVDL MODE 2 SARPs: ATN SARPsLayer 1Layer 2Layer 3Layer 4Layer 5Layer 6Layer 7SNAcP (ISO 8208) Figure 1: VDL SARPS in the ATN/OSI Organization SIST EN 301 841-1 V1.3.1:2010
ETSI ETSI EN 301 841-1 V1.3.1 (2010-06) 12 5 Physical layer protocols and services functional specifications 5.1 Overview The ground stations shall access the physical layer operating in simplex mode. 5.1.1 Functions The tasks of the physical layer include the following: • to modulate and demodulate radio carriers with a bit stream of a defined instantaneous rate to create an rf link; • to acquire and maintain bit and burst synchronization between Transmitters and Receivers; • to transmit or receive a defined number of bits at a requested time (packet mode) and on a particular carrier frequency; • to add and remove a training sequence; • to encode and decode the Forward Error Correction scheme; • to measure received signal strength; • to decide whether a channel is idle or busy, for the purposes of managing channel access attempts; • to offer a notification service about the quality of link. 5.1.2 Data reception by the receiver The receiver shall decode input signals and forward them to the higher layers for processing. 5.1.3 Data transmission The VDL physical layer shall appropriately encode the data received from the data link layer and transmit it over the rf channel. 5.2 Transmission procedure To transmit a sequence of frames, a station shall insert the bit numbers and, compute the FEC, interleave, insert the training sequence, carry out bit scrambling, and finally encode and modulate the rf signal. See figure 2. SIST EN 301 841-1 V1.3.1:2010
ETSI ETSI EN 301 841-1 V1.3.1 (2010-06) 13 segment into RS blocksRS encoderinterleaverPreparetraining sequenceAVPL_THeadersymbol segmentationsymbol data burst to modulator(s)AVLC_LIbit scramblerTIRS_matrix(i,j)AVPL_TIRS sequenceAVPL_THI sequenceAVPL_TBS sequenceAVPL_TTS sequenceAVLC_LIAVLC_LIAVLC frame of length AVLC_LI to be transmitted Figure 2: Data burst formatting procedure 5.3 Modulation scheme Mode 2 shall use D8PSK, using a raised cosine filter with α = 0,6 (nominal value). The information to be transmitted shall be differentially encoded with 3 bits per symbol transmitted as changes in phase rather than absolute phase. The data stream to be transmitted shall be divided into groups of 3 consecutive data bits, with the least significant bit first. Zeros shall be padded to the end of the transmissions if needed for the final channel symbol. SIST EN 301 841-1 V1.3.1:2010
ETSI ETSI EN 301 841-1 V1.3.1 (2010-06) 14 5.4 Training sequence Data transmission shall begin with a demodulator training sequence consisting of five segments: • transmitter ramp up and power stabilization (5 symbols); • synchronization and ambiguity resolution (16 symbols - the "unique word"); • reserved symbol (1 symbol); • transmission length (a single 17 bit word); • header FEC (5 bits). NOTE: Immediately after these segments there is an AVLC frame.
transmitter power synchronization and reserved transmission length header stabilization sequence ambiguity sequence (AVLC_LI) symbol FEC
Figure 3: AVPL-header training sequence structure 5.4.1 RF power rise time definition The purpose of the first segment of the training sequence, called the ramp-up, is to provide for transmitter power stabilization and receiver AGC settling and it shall immediately precede the first symbol of the unique word. The first segment also provides AGC settling time for the intended receiver. The time reference point (T), for the following specification is the centre of the first unique word symbol, a point that occurs 1/2 a symbol period after the end of the first segment. The start of the first segment is therefore defined at time T = -5,5 symbol periods. Steady StateMode2 Ramp up00,10,20,30,40,50,60,7-9-8-7-6-5-4-3-2-101234T (Symbol periods)Envelope Key:
Symbol increment
Figure 4: Transmitter Power Stabilization NOTE: There is a characteristic deep notch in the training sequence (see figure 4) which is located 2,5 symbol periods after the first synchronization symbol (T0). Therefore, the rf power level can be checked 5,5 symbol periods (524 µs) before this "marker" at T-
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