SIST EN ISO 14819-6:2006
(Main)Traffic and Traveller Information (TTI) - TTI messages via traffic message coding - Part 6: Encryption and conditional access for the Radio Data System - Traffic Message Channel ALERT C coding (ISO 14819-6:2006)
Traffic and Traveller Information (TTI) - TTI messages via traffic message coding - Part 6: Encryption and conditional access for the Radio Data System - Traffic Message Channel ALERT C coding (ISO 14819-6:2006)
This document establishes a method of encrypting certain elements of the ALERT-C coded data carried in the RDS-TMC type 8A data group, such that without application by a terminal or receiver of an appropriate key, the information conveyed is virtually worthless. Before a terminal is able to decrypt the data, the terminal requires two "keys". The first is given in confidence by the service provider to terminal manufacturers with whom they have a commercial relationship; the second is broadcast t in the "Encryption Administration Group," which is also a type 8A group. This International Standard explains the purpose of the two keys and how often and when the transmitted key may be changed. Before an individual terminal may present decrypted messages to the end-user, it must have been activated to do so. Activation requires that a PIN code be entered. The PIN code controls access rights to each service and subscription period, allowing both lifetime and term business models to co-exist. The International Standard also describes the considerations for service providers wishing to introduce an encrypted RDS-TMC service, migrating from either a "free-to-air" service based on public "Location Tables" or a commercial service based on a proprietary Location Table. Finally, "hooks" have been left in the bit allocation of the type 8A group to allow extension of encryption to other RDS-TMC services.
Verkehrs- und Reiseinformationen-TTI - Meldungen über Verkehrsmeldungscodierung - Teil 6: Verschlüsselung und Zugangsbedingungen für das Radio Datensystem - Verkehrsmeldungskanal ALERT C Kodierung (ISO 14819-6:2006)
Informations sur le trafic et le tourisme (TTI) - Messages TTI via le codage de messages sur le trafic - Partie 6: Acces au cryptage et acces conditionnel pour le systeme de radiodiffusion de données - Codage ALERT C du canal de messages sur le trafic (ISO 14819-6:2006)
L'ISO 14819-6:2006 établit une méthode de chiffrement de certains éléments de données codées en ALERT-C transportés dans le groupe de données RDS-TMC du type 8A afin que les informations acheminées n'aient virtuellement aucune valeur sans l'application par un terminal ou récepteur d'une clé adéquate.
Avant qu'un terminal ne puisse déchiffrer les données, il lui faut deux «clés». La première est donnée en toute confiance par le prestataire de services aux fabricants de terminaux avec lesquels il entretient une relation commerciale; la seconde est diffusée dans le «Groupe de gestion du chiffrement», qui est aussi un groupe de type 8A. L'ISO 14819-6:2006 explique le but des deux clés ainsi que la fréquence et le moment auxquels il est permis de changer la clé émise.
Avant qu'un terminal individuel ne puisse présenter des messages déchiffrés à l'utilisateur final, il faut l'activer à cet effet. L'activation requiert la saisie d'un code PIN. Le code PIN commande les droits d'accès à chaque service et la période d'abonnement, permettant la coexistence de modèles commerciaux tant à terme qu'à vie.
L'ISO 14819-6:2006 décrit aussi les considérations pour les prestataires de services souhaitant introduire un service RDS-TMC chiffré, en migrant d'un service «à diffuser en clair» basé sur des «Tables de localisants» publiques ou d'un service commercial basé sur une «Table de localisants» propriétaire.
Finalement, des «crochets» ont été laissés dans l'allocation des bits du groupe de type 8A pour permettre l'extension du chiffrement à d'autres services du RDS-TMC.
Prometne in potovalne informacije (TTI) - Sporočila TTI prek kodiranih prometnih sporočil – 6. del: Enkripcija in pogojni dostop za radijski podatkovni sistem (RDS) – Prometni sporočilni kanal s kodiranjem ALERT C (ISO 14819-6:2006)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 14819-6:2006
01-september-2006
3URPHWQHLQSRWRYDOQHLQIRUPDFLMH 77, 6SRURþLOD77,SUHNNRGLUDQLKSURPHWQLK
VSRURþLO±GHO (QNULSFLMDLQSRJRMQLGRVWRS]DUDGLMVNLSRGDWNRYQLVLVWHP 5'6
±3URPHWQLVSRURþLOQLNDQDOVNRGLUDQMHP$/(57& ,62
Traffic and Traveller Information (TTI) - TTI messages via traffic message coding - Part
6: Encryption and conditional access for the Radio Data System - Traffic Message
Channel ALERT C coding (ISO 14819-6:2006)
Verkehrs- und Reiseinformationen-TTI - Meldungen über Verkehrsmeldungscodierung -
Teil 6: Verschlüsselung und Zugangsbedingungen für das Radio Datensystem -
Verkehrsmeldungskanal ALERT C Kodierung (ISO 14819-6:2006)
Informations sur le trafic et le tourisme (TTI) - Messages TTI via le codage de messages
sur le trafic - Partie 6: Acces au cryptage et acces conditionnel pour le systeme de
radiodiffusion de données - Codage ALERT C du canal de messages sur le trafic (ISO
14819-6:2006)
Ta slovenski standard je istoveten z: EN ISO 14819-6:2006
ICS:
03.220.20 Cestni transport Road transport
35.240.60 Uporabniške rešitve IT v IT applications in transport
transportu in trgovini and trade
SIST EN ISO 14819-6:2006 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 14819-6:2006
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SIST EN ISO 14819-6:2006
EUROPEAN STANDARD
EN ISO 14819-6
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2006
ICS 03.220.20; 35.240.60
English Version
Traffic and Traveller Information (TTI) - TTI messages via traffic
message coding - Part 6: Encryption and conditional access for
the Radio Data System - Traffic Message Channel ALERT C
coding (ISO 14819-6:2006)
Informations sur le trafic et le tourisme (TTI) - Messages Verkehrs- und Reiseinformationen-TTI - Meldungen über
TTI via le codage de messages sur le trafic - Partie 6: Verkehrsmeldungscodierung - Teil 6: Verschlüsselung und
Accès au cryptage et accès conditionnel pour le système Zugangsbedingungen für das Radio Datensystem -
de radiodiffusion de données - Codage ALERT C du canal Verkehrsmeldungskanal ALERT C Kodierung (ISO 14819-
de messages sur le trafic (ISO 14819-6:2006) 6:2006)
This European Standard was approved by CEN on 20 March 2006.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Central Secretariat or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,
Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2006 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 14819-6:2006: E
worldwide for CEN national Members.
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SIST EN ISO 14819-6:2006
EN ISO 14819-6:2006 (E)
Foreword
This document (EN ISO 14819-6:2006) has been prepared by Technical Committee CEN/TC
278 "Road transport and traffic telematics", the secretariat of which is held by NEN, in
collaboration with Technical Committee ISO/TC 204 "Transport information and control
systems".
This European Standard shall be given the status of a national standard, either by publication of
an identical text or by endorsement, at the latest by October 2006, and conflicting national
standards shall be withdrawn at the latest by October 2006.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary,
Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
2
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SIST EN ISO 14819-6:2006
INTERNATIONAL ISO
STANDARD 14819-6
First edition
2006-04-15
Traffic and Traveller Information (TTI) —
TTI messages via traffic message
coding —
Part 6:
Encryption and conditional access for the
Radio Data System — Traffic Message
Channel ALERT C coding
Informations sur le trafic et le tourisme (TTI) — Messages TTI via le
codage de messages sur le trafic —
Partie 6: Accès au cryptage et accès conditionnel pour le système de
radiodiffusion de données — Codage ALERT C du canal de messages
sur le trafic
Reference number
ISO 14819-6:2006(E)
©
ISO 2006
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SIST EN ISO 14819-6:2006
ISO 14819-6:2006(E)
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ii © ISO 2006 – All rights reserved
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SIST EN ISO 14819-6:2006
ISO 14819-6:2006(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Symbols and abbreviations . 3
5 Notation . 4
6 Application description. 4
6.1 Introduction to RDS group bit pattern and notation . 4
6.2 RDS-TMC and Open Data Application . 5
6.3 Summary of TMC data elements in type 8A groups. 7
7 Principles of the Encryption and Conditional Access methodology . 8
8 Encryption by the service provider. 9
8.1 Service provider’s requirements. 9
8.2 Use of type 8A groups for RDS-TMC encryption. 9
8.3 Encryption Administration group . 10
8.4 Encrypting location codes. 12
9 Access to decrypted services by a terminal. 13
9.1 Terminal manufacturer’s basic requirements. 13
9.2 Activation of a terminal . 14
9.3 Identifying an encrypted RDS-TMC service . 15
9.4 Decrypting location codes. 15
10 Introduction of Encrypted services . 16
10.1 Terminal responses. 17
10.2 De facto strategy valid only for service providers wishing to generate revenue, prior to
general availability of encryption. 17
10.3 Actions for existing providers of unencrypted TMC services . 17
10.4 Actions for potential providers of TMC services. 18
10.5 Timescales. 18
Bibliography . 19
© ISO 2006 – All rights reserved iii
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SIST EN ISO 14819-6:2006
ISO 14819-6:2006(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 14819-6 was prepared by Technical Committee ISO/TC 204, Intelligent transport systems, in
collaboration with CEN Technical Committee CEN/TC 278, Road transport and traffic telematics, the
secretariat of which is held by NEN.
ISO 14819 consists of the following parts, under the general title Traffic and Traveller Information (TTI) — TTI
messages via traffic message coding:
— Part 1: Coding protocol for Radio Data System — Traffic Message Channel (RDS-TMC) using ALERT-C
— Part 2: Event and information codes for Radio Data System — Traffic Message Channel (RDS-TMC)
— Part 3: Location referencing for ALERT-C
— Part 6: Encryption and conditional access for the Radio Data System — Traffic Message Channel ALERT
C coding
iv © ISO 2006 – All rights reserved
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SIST EN ISO 14819-6:2006
ISO 14819-6:2006(E)
Introduction
Traffic and traveller information may be disseminated through a number of services or means of
communication. For such services, the data to be disseminated and the message structure involved in the
various interfaces require clear definition and standard formats, in order to allow competitive products to exist
with any received data.
The most widely supported data specification for TTI messages within Europe and elsewhere is RDS-TMC,
specified in Parts 1, 2 and 3 of EN ISO 14819. In RDS-TMC, TTI messages are conveyed using type 8A
groups with the Radio Data System, itself specified in EN 62106.
The RDS-TMC standard was developed principally for the purposes of disseminating TTI data ‘free-to-air’,
using a public-service model.
However, in many countries, the adoption and continuance of TTI services requires a business model based
on commercial principals whereby the costs for the collection of the data and its dissemination may be
recovered by charging end-users or intermediaries to receive and use the data. In this model, a convenient
way that this may be achieved is to encrypt the data in some way, the key to decrypt the data being made
available on payment of a subscription or fee. In order to avoid a proliferation of different conditional access
systems, the European receiver industry asked the TMC Forum to establish a Task Force to recommend a
single method of encryption capable of being widely adopted.
The task force established criteria that any encryption method would have to fulfil. These included:
⎯ conformity with the RDS and TMC specifications and guidelines;
⎯ no, or only minimal, overhead in terms of data capacity required for encryption;
⎯ no hardware change to existing terminals required;
⎯ availability for use by service providers and terminal manufacturers “freely” and “equitably”, either free-of-
charge or on payment of a modest licence fee;
⎯ applicability to both lifetime and term subscription business models;
⎯ ability of terminals to be activated to receive an encrypted service on an individual basis.
After calling for candidate proposals, the submission from Deutsche Telekom was judged by an expert panel
to have best met the pre-determined criteria the task force had established. The method encrypts the 16 bits
that form the Location element in each RDS-TMC message to render the message virtually useless without
decryption. The encryption is only “light” but was adjudged to be adequate to deter all but the most determined
hacker. More secure systems were rejected because of the RDS capacity overhead that was required.
After ratification of the decision to adopt the Deutsche Telekom submission by the TMC Forum Business
Group and Management Group, a group was appointed and given the remit to elaborate it and present it as a
specification to be submitted for standardization. The group was also requested to produce guidelines for
service providers and terminal manufacturers to aid implementation of the specification.
This International Standard describes a non-proprietary light encryption and conditional access system that
allows commercial models for RDS-TMC to exist. The reader is assumed to have a pre-existing understanding
of, and familiarity with, the RDS and RDS-TMC standards and implementation guidelines.
© ISO 2006 – All rights reserved v
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SIST EN ISO 14819-6:2006
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SIST EN ISO 14819-6:2006
INTERNATIONAL STANDARD ISO 14819-6:2006(E)
Traffic and Traveller Information (TTI) — TTI messages via
traffic message coding —
Part 6:
Encryption and conditional access for the Radio Data
System — Traffic Message Channel ALERT C coding
1 Scope
This document establishes a method of encrypting certain elements of the ALERT-C coded data carried in the
RDS-TMC type 8A data group, such that without application by a terminal or receiver of an appropriate key,
the information conveyed is virtually worthless.
Before a terminal is able to decrypt the data, the terminal requires two “keys”. The first is given in confidence
by the service provider to terminal manufacturers with whom they have a commercial relationship; the second
is broadcast in the “Encryption Administration Group,” which is also a type 8A group. This International
Standard explains the purpose of the two keys and how often and when the transmitted key may be changed.
Before an individual terminal may present decrypted messages to the end-user, it must have been activated to
do so. Activation requires that a PIN code be entered. The PIN code controls access rights to each service
and subscription period, allowing both lifetime and term business models to co-exist.
The International Standard also describes the considerations for service providers wishing to introduce an
encrypted RDS-TMC service, migrating from either a “free-to-air” service based on public “Location Tables” or
a commercial service based on a proprietary Location Table.
Finally, “hooks” have been left in the bit allocation of the type 8A group to allow extension of encryption to
other RDS-TMC services.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 14819-1, Traffic and Traveller Information (TTI) — TTI messages via traffic message coding — Part 1:
Coding protocol for Radio Data System — Traffic Message Channel (RDS-TMC) using ALERT-C
ISO 14819-2, Traffic and Traveller Information (TTI) — TTI messages via traffic message coding — Part 2:
Event and information codes for Radio Data System — Traffic Message Channel (RDS-TMC)
ISO 14819-3, Traffic and Traveller Information (TTI) — TTI messages via traffic message coding — Part 3:
Location referencing for ALERT-C
EN 62106, Specification of the radio data system (RDS) for VHF/FM sound broadcasting in the frequency
range from 87, 5 to 108, 0 MHz (IEC 62106:2000)
© ISO 2006 – All rights reserved 1
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SIST EN ISO 14819-6:2006
ISO 14819-6:2006(E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
Access Profile
ACP
a particular service and subscription period
3.2
Country Code
CC
code assigned to a country to be transmitted as the first four bits of the transmitted PI code in a broadcast
RDS service
[EN 62106]
3.3
Encryption Identifier
ENCID
value indicating which line in the Service Key table of parameters the service provider is using in the
encryption process that day
NOTE ENCID is transmitted in type 8A groups.
3.4
Event Description
details of the road situation, general or specific traffic problems, and other factors (e.g. weather) affecting or
potentially affecting the passage of vehicles on the roads and highways network
3.5
Expiry Date
date determined by the service provider on which a particular terminal’s ability to decrypt an encrypted service
should cease (i.e. end of the paid subscription period)
3.6
Location
area, highway segment or point location where the source of the problem is situated
3.7
Location Code
numeric or alphanumeric representation of a location according to a pre-determined database, known as a
Location Table
3.8
Location Table Number
LTN
number with the value 0 to 63 used to identify the Location Table used by the service provider.
NOTE 1 The LTN is generally allocated to each service provider in a country by the relevant government or roads
authority from a range assigned to that country. It is transmitted in type 3A groups.
NOTE 2 Value 0, when transmitted in type 3A groups, shows that the service provider is encrypting the location codes
transmitted in the manner described in this International Standard.
2 © ISO 2006 – All rights reserved
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SIST EN ISO 14819-6:2006
ISO 14819-6:2006(E)
3.9
Location Table Number Before Encryption
LTNBE
number with the value 1 to 63 used to identify the Location Table used by the service provider prior to the
codes within the table being encrypted for transmission
NOTE LTNBE is transmitted in type 8A groups.
3.10
Other Network
ON
notation appended in drawings, where necessary, to indicate that the code being transmitted [e.g. SID (ON)]
relates not to the Tuned Service, but to a referenced Other Network
NOTE Data about the Other Network(s) can be pre-stored in terminal equipment.
3.11
PIN code
numeric or alphanumeric code required to be entered into a terminal before that terminal is permitted to
present decrypted RDS-TMC messages
NOTE The value of the PIN code is calculated by the terminal manufacturer from an algorithm using terminal serial
number and one or more application profiles as factors.
3.12
Serial Number
alphanumeric identifier, unique to a terminal (or group of terminals), determined by the manufacturer
3.13
Service Identifier
SID
Code uniquely identifying a TMC service provided by a service provider
3.14
Service Key
SVK
number given in confidence by a service provider to a terminal manufacturer, identifying which one of eight
possible encryption tables the service is using for encryption
NOTE The Service Key is NOT transmitted.
3.15
Service Provider
organization that manages any data service, by gathering data, processing data, and selling the data service
NOTE The service provider negotiates for the use of the necessary data bandwidth for transmission with a
Broadcaster or Transmission Operator.
4 Symbols and abbreviations
ACP Access Profile
AID Application IDentification
CC Country Code
ENCID ENCryption IDentifier
LTN Location Table Number
© ISO 2006 – All rights reserved 3
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SIST EN ISO 14819-6:2006
ISO 14819-6:2006(E)
LTNBE Location Table Number Before Encryption
MGS Message Geographical Scope
ODA Open Data Application
ON Other Network
PI Programme Identification
RDS Radio Data System
rfu reserved for future use
SID Service IDentifier
SVK Service Key
TMC Traffic Message Channel
UTC Coordinated Universal Time
5 Notation
In this International Standard, numbers are DECIMAL, unless specifically indicated otherwise, e.g. 1234 (hex).
6 Application description
In 6.1 and 6.2 below, the basics of RDS and RDS-TMC are introduced in order to provide the reader with the
framework necessary to understand the method of encryption detailed in this International Standard.
6.1 Introduction to RDS group bit pattern and notation
The general format for all RDS data groups is as shown in Figure 1. Of the sixty-four data bits in each group,
the sixteen in Block 1, and the first eleven in Block 2, have specific values essential to the correct operation of
the basic RDS system features. The remaining thirty-seven bits, indicated in RDS-TMC with the notation X4-
X0, Y15-Y0 and Z15-Z0 have uses specific to the particular RDS feature or application being coded.
Key
1 PI code 4 Checkword and Offset B
2 Checkword and Offset A 5 Checkword and Offset C
3 Group type code 6 Checkword and Offset D
Figure 1 — RDS data group
4 © ISO 2006 – All rights reserved
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SIST EN ISO 14819-6:2006
ISO 14819-6:2006(E)
6.2 RDS-TMC and Open Data Application
RDS-TMC using the ALERT-C protocol is defined in ISO 14819-1.
It is an example of an RDS ODA, which allows the application to be transmitted in any appropriate unused
RDS group type in the particular RDS service. The application identified by its AID code, and the group in
which it is being transmitted is identified using a type 3A group, which in effect acts as an index for all ODAs.
The structure of an ODA type 3A group is given in Figure 2. The AID code for ALERT-C coded RDS-TMC
messages is CD46 (hex), indicated in Block 4, bits Z15 to Z0. The group type carrying the RDS-TMC data –
which by convention is a type 8A group – is given by bits X4 to X0.
Key
1 PI code
2 Checkword and Offset A
3 Group type code
4 Checkword and Offset B
5 Checkword and Offset C
6 Checkword and Offset D
Figure 2 — Type 3A group (ODA) indicating RDS-TMC (CD46 (hex)) carried in group 8A
The bits in Y15 to Y0 are used to convey parameters describing the nature and transmission details of the
particular RDS-TMC service.
Two variants have been defined, which are fully described in ISO 14819-1; they are summarized as follows:
6.2.1 Variant 0
In variant 0, bits Y5 to Y0 indicate the AFI, the Mode of Transmission Indicator (M) and MGS elements.
Bits Y11 to Y6 indicate LTN for the service, which in terms of this International Standard which describes
encryption, is the most important element. The value of LTN indicates whether or not the location codes
(carried in the type 8A groups) are “encrypted”.
In older versions of ISO 14819-1, LTN = 0 was an excluded value, and only values of 1 to 63 were permitted.
This International Standard now makes use of this previously excluded zero value to indicate an encrypted
service.
Non-zero LTN values in a type 3A group indicate non-encrypted services; these may be either free-to-air
services using a publicly available Location Table, or services which use a proprietary Location Table to
restrict use. In either case, in order to produce any valid messages, the terminal must have access to the
Location Table identified by the LTN.
An encrypted RDS-TMC service is indicated by an LTN with value 0 in the type 3A group. The LTN used by
the service provider, the codes of which are now to be encrypted, is given by the element LTNBE, transmitted
in the Encryption Administration Group, described in 8.3 below.
© ISO 2006 – All rights reserved 5
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SIST EN ISO 14819-6:2006
ISO 14819-6:2006(E)
Block 4 (Bits Z15 to Z0) will always be set to the value CD46, which is the AID identifying an RDS-TMC
service.
Key
1 PI code
2 Checkword and Offset A
3 Group type code
4 Checkword and Offset B
5 Checkword and Offset C
6 Checkword and Offset D
Figure 3 — Type 3A group, RDS-TMC variant 0, carrying system information
A type 3A group variant 0 shall be transmitted at least once every 5 s.
6.2.2 Variant 1
In variant 1, bits Y11 to Y6 indicate the SID.
Bits Y13 to Y12, Y5 to Y4, Y3 to Y2 and Y1 to Y0 are used to detail respectively the values of Gap (G), activity
time (Ta), window time (Tw) and delay time (Td) when the “Spinning Wheel” mode of transmission is used.
This is fully specified in ISO 14819-1.
Block 4 (Bits Z15 to Z0) will always be set to the value CD46, which is the AID identifying an ALERT-C RDS-
TMC service.
Key
1 PI code
2 Checkword and Offset A
3 Group type code
4 Checkword and Offset B
5 Checkword and Offset C
6 Checkword and Offset D
Figure 4 — Type 3A group, RDS-TMC variant 1, carrying system information
6 © ISO 2006 – All rights reserved
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SIST EN ISO 14819-6:2006
ISO 14819-6:2006(E)
A type 3A group variant 1 shall be transmitted at least once every 10 s, as defined in ISO 14819-1.
Using the SID which is also included within the Encryption Administration group (see 8.3 below) may help
terminals to increase the search process for encrypted services.
6.3 Summary of TMC data elements in type 8A groups
Details of particular traffic situations are carried in the RDS-TMC user messages, transmitted as type 8A
groups. They provide the following six basic items of information:
⎯ Event Description — giving details of the traffic situation, or other factor (e.g. weather) affecting or
potentially affecting traffic. An 11-bit number represents the event description, a common table being
used by all service providers. The list of numbers and associated descriptions are in ISO 14819-2.
⎯ Location — indicating the area, highway segment or point of the source of the traffic situation. The
location is indicated
...
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