ETSI ETS 300 708 ed.1 (1997-03)

SLOVENSKI STANDARD
SIST ETS 300 708 E1:2003
01-december-2003
Televizijski sistemi – Prenos podatkov v sistemu Teletext
Television systems; Data transmission within Teletext
Ta slovenski standard je istoveten z: ETS 300 708 Edition 1
ICS:
33.050.30 Oprema za teleks, teletekst, Equipment for telex, teletext,
telefaks telefax
33.170 Televizijska in radijska Television and radio
difuzija broadcasting
SIST ETS 300 708 E1:2003 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the

Whilst every care has been taken in the preparation and publication of this document, errors in content,

typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to

"ETSI Editing and Committee Support Dept." at the address shown on the title page.

Foreword .......................................................................................................................................................5

1 Scope ..................................................................................................................................................7

2 Normative references..........................................................................................................................7

3 Definitions and abbreviations ..............................................................................................................7

3.1 Definitions ............................................................................................................................7

3.2 Abbreviations .......................................................................................................................8

4 Page Format - Clear............................................................................................................................8

4.1 General points......................................................................................................................8

4.2 Advantages..........................................................................................................................8

4.3 Disadvantages .....................................................................................................................8

4.4 Coding of the packets ..........................................................................................................8

4.4.1 Page header....................................................................................................9

4.4.2 Packets 1 to 23 (in future up to 25) ...............................................................10

4.4.2.1 Transmission order..............................................................11

4.4.2.2 The Structure Header (SH)..................................................11

4.4.2.3 Packing the data into the pages ..........................................11

4.4.3 Packet 28 ......................................................................................................12

4.5 Providing a service according to Page Format - Clear ......................................................12

4.5.1 General points on Page Format - Clear ........................................................13

4.5.2 Encoding scheme for electronic data transmission.......................................13

5 Page Format - CA .............................................................................................................................13

5.1 General points....................................................................................................................13

5.2 Advantages........................................................................................................................13

5.3 Disadvantages ...................................................................................................................14

5.4 Method of coding ...............................................................................................................14

5.4.1 Teletext page data.........................................................................................15

5.4.1.1 Scrambled Data Pages........................................................15

5.4.2 The Page Key Packet....................................................................................16

5.4.2.1 Service Mode bits ................................................................16

5.4.2.2 Service Identification............................................................17

5.4.2.3 Continuity and Repeat Indicators.........................................17

5.4.2.4 Packet Flags........................................................................17

5.4.2.5 Data Length .........................................................................17

5.4.2.6 Scrambling Method..............................................................18

5.4.3 Terminal Equipment Addressing Pages........................................................19

5.4.3.1 System Key Packet..............................................................19

5.4.3.2 Shared User Packets...........................................................19

5.4.3.3 Unique User Packets...........................................................20

5.4.3.4 Service/Page Link packets ..................................................21

5.5 Security of Page Format - CA............................................................................................21

5.5.1 Cipher feedback algorithm ............................................................................21

5.5.2 One-way function...........................................................................................22

5.5.3 Text scrambling.............................................................................................23

6 Independent Data Lines (IDL) ...........................................................................................................23

6.1 General points....................................................................................................................23

6.2 Advantages........................................................................................................................23

6.3 Disadvantages ...................................................................................................................23

6.4 Methods of coding..............................................................................................................23

6.4.1 Designation code .......................................................................................... 23

6.4.1.1 Transmission multiplexing................................................... 23

6.4.2 Data Channel addressing ............................................................................. 23

6.5 IDL Format A..................................................................................................................... 24

6.5.1 Format Type (FT) ......................................................................................... 24

6.5.2 Interpretation and Address Length (IAL)....................................................... 24

6.5.3 Service Packet Address (SPA)..................................................................... 25

6.5.4 Repeat Indicator (RI) .................................................................................... 25

6.5.5 Continuity Indicator (CI) ................................................................................ 25

6.5.6 Data Length (DL) byte................................................................................... 25

6.5.7 User Data Group........................................................................................... 25

6.5.7.1 Dummy bytes ...................................................................... 26

6.5.8 Cyclic Redundancy Check (CRC) word........................................................ 26

6.5.8.1 Check word generation ....................................................... 26

6.5.9 Transmission sequence................................................................................ 27

6.6 Datavideo format............................................................................................................... 27

6.6.1 Packet address............................................................................................. 27

6.6.2 Control Bytes (CB)........................................................................................ 27

6.6.2.1 Packet Continuity Indicator (CI) .......................................... 27

6.6.3 Masking indicator.......................................................................................... 27

6.6.4 Packet type indicator .................................................................................... 28

6.6.5 User data group............................................................................................ 28

6.6.6 Cyclic Redundancy Check (CRC) word........................................................ 28

6.6.6.1 Check word generation ....................................................... 28

6.6.6.2 Check result ........................................................................ 28

6.7 Low bit-rate audio.............................................................................................................. 28

6.7.1 Method of coding .......................................................................................... 29

6.7.1.1 Decoder action.................................................................... 29

6.7.2 Programme-related audio service ................................................................ 29

6.7.2.1 Service Byte (SB)................................................................ 29

6.7.2.2 Control Byte (CB) ................................................................ 29

6.7.2.3 Audio data........................................................................... 30

6.7.3 Programme independent audio service........................................................ 30

6.7.3.1 Service Byte (SB)................................................................ 30

6.7.3.2 Control Byte (CB) ................................................................ 30

6.7.3.3 Audio data........................................................................... 30

7 IDL - CA (type A) .............................................................................................................................. 30

7.1 General points................................................................................................................... 30

7.2 Advantages ....................................................................................................................... 31

7.3 Disadvantages................................................................................................................... 31

7.4 Methods of coding............................................................................................................. 31

7.4.1 Block Separator ............................................................................................ 31

7.4.2 Block Formats............................................................................................... 31

7.4.3 Block Format A ............................................................................................. 31

7.4.3.1 Block Types......................................................................... 31

7.4.3.2 Primary Block Key Messages ............................................. 32

7.4.3.4 System-Key Message Block ............................................... 32

7.4.3.5 Shared-User Message Block .............................................. 32

7.4.3.6 Unique User Message Block............................................... 33

Service ................................................................................ 33

CA ....................................................................................... 33

History......................................................................................................................................................... 34

This European Telecommunication Standard (ETS) has been produced by the Joint Technical Committee

(JTC) of the European Broadcasting Union (EBU), Comité Européen de Normalisation ELECtrotechnique

NOTE: The EBU/ETSI JTC was established in 1990 to co-ordinate the drafting of ETSs in the

specific field of broadcasting and related fields. Since 1995 the JTC became a tripartite

responsible for the standardization of radio and television receivers. The EBU is a

co-ordination of its Members' activities in the technical, legal, programme-making and

This European Telecommunication Standard (ETS) describes the various ways in which Teletext may be

used to carry non-Teletext services. It should be used in conjunction with ETS 300 706 [1]. An example is

fully described in ETS 300 707 [2]. This ETS includes additional practical information on implementing a

Hooks into existing Teletext services may be provided from within the application which is carried as a

non-Teletext service. A data broadcast application may be pointed to from the Magazine Inventory Page

(MIP) or it may be allocated a specific page number. A Code of Practice (CoP) shall ensure that services

destined for the consumer may be found quickly by "low-end" Teletext decoders but this is outside the

There are two methods available for carrying data services. The first method carries the data within

Teletext pages. The data in these pages is not sui for direct display by a Teletext decoder and shall

normally be allocated a special page number and/or have the display inhibited. The second method

carries the data within Independent Data Lines (IDL) and these are independent of the page service.

With both Page and IDL formats there exist versions which offer Conditional Access (CA).

There are other specific IDL data services which have been defined but it is beyond the scope of this ETS

This ETS incorporates, by dated or undated references, provisions from other publications. These

normative references are cited at the appropriate places in the text, and the publications are listed

hereafter. For dated references subsequent amendments to, or revisions of, any of these publications

apply to this ETS only when incorporated in it by amendment or revision. For undated references the latest

data stream: The sequence of bytes carried in a uniquely addressable data service.

encryption: The process whereby a sequence of data is made secret. See subclause 5.5 for further

network operator: The organization responsible for the compilation of the Teletext service for insertion

scrambling: The process whereby a sequence of data is made unintelligible. See subclause 5.5 for

service provider: The organization responsible for the creation and supply of the data service application.

A page number which includes at least one hexadecimal digit should be chosen for this type of service.

For an Electronic Programme Guide (EPG) service this will generally be page 1DF as fully described in

ETS 300 707 [2]. The value nFF is not permitted for any data service, where n can take the value from

1 to 8 inclusive. The page number is defined in the Magazine Inventory Page (MIP), ETS 300 706 [1].

The user data is divided into blocks, each of whose length is defined. An additional check of where the

block boundaries are located is provided by means of a block pointer placed in the first byte in each

packet. The data stream is further identified by means of additional data provided in the page header. It is

This mode is appropriate for reception by all existing Teletext decoders. A default coding method is

defined in order that services may be offered using existing Teletext systems. Synchronization of the user

data blocks is assured by means of a simple robust method of dual pointing to each block start location.

Future possibilities exist by providing an additional packet 28 which will further define the coding system in

use. It is left up to the service provider to apply any additional protection to those parts of his service which

require it. It is possible to sub-divide the service into those parts which will be required by all decoders and

This mode is not efficient for sending a small amount of data as there is always the overhead of including

a page header and the optional, but useful, packet 28. Another disadvantage of this mode is that the data

transmission efficiency is further reduced when the Teletext broadcaster wishes to send the data in a

fragmented way in order to interleave the data service with his primary Teletext service.

In order to provide greater flexibility for the network operator it is not necessary to fill each data page.

Several separated headers, each with some data packets, may be required to provide the data service

and this technique is covered fully in ETS 300 706 [1]. In the case of a data service it is possible to send

Fragmented pages are usually interleaved with one or more other pages. Each fragmented page contains,

in row order, parts of a full page. Fragmented pages transmitted in stream 1 shall obey the 20 ms rule for

This is necessary but shall not generally contain any of the application data. It may be identical to all

others in the same magazine. The use of the Teletext page sub-code is defined as shown in figure 1.

The default valid range for the number of packets is 1 to 23 where this value provides the last row

which is being transmitted for the page with this particular value for the Continuity Index (CI). The packets

of the page are transmitted in ascending address order. There are no missing rows and where a new

header is required to complete the page then this shall be provided with the same CI. The maximum

number of packets per page is 25 and as a result S2 and S4 will never have values of 7 and 3

simultaneously. Thus the reserved sub-code value of 3F7F defined in ETS 300 706 [1] can never occur.

As expected the Least Significant Bit (LSB) of each parameter in the page sub-code is transmitted first.

The 20 ms rule requires that the header packet 0 is sent during a previous field. This rule shall be

followed when the LSB of S3 is set to 0. When this bit is set to 1 then the header may be followed

immediately by the packets associated with this header. The following values have been defined in

4, 6, 8, A, C & E 20 ms rule applies - data stream 5, 7, 9, 11, 13 & 15 respectively

In each stream the CI value increments modulo 16 for each page which contains different application

The values for C5, C6, C7, C8, C11, C12, C13 and C14 depend upon the type of service which the

network provider is offering and have the same meaning as for normal Teletext pages. The following

The next 24 bytes should normally match those of the other pages in the same magazine. This is to avoid

possible display problems with viewers of the normal Teletext service which shares this Magazine.

The last 8 bytes of the header shall be used in a way which takes account of the rest of the Teletext

service. Where the time can be the same as that on the normal Teletext service it shall be presented in

the same format. Where this is not possible these 8 bytes should be filled with spaces. In the case where

there is no other Teletext service then the local time shall be placed in these 8 bytes according to the

These packets may carry the data service. The page sub-code indicates to the decoder how many

packets to expect. The default maximum number of packets is 23 although future services may be able to

use up to 25. Each Teletext packet is constructed in the manner shown in figure 2.

This follows the normal Teletext format where the LSB is transmitted first. For example in the Structure

Header (SH) the least significant 4 bits of the Block Type shall be placed in the byte which is transmitted

first. The most significant bit of BT shall be placed in the least significant position of the next byte.

The Hamming 8/4 coding is carried out in the same way as fully described in ETS 300 706 [1]. The bytes

defined above are all transmitted in the same way. It is up to the data service provider how he codes

the bytes which constitute the "user data". The values for BP are given in table 3.

The SH comprises four Hamming 8/4 coded bytes. This is put in by the data service provider and the 16

Shown in transmission order from left to right. LSB transmitted first. Only the data bytes are shown.

The first 5 bits (BT) provide the Application ID. This gives the data application provider the possibility of

providing up to 31 different categories of data within one page service. This is addition to the separation

into a number of streams which is possible by means of the page sub-code value for S3. The actual value

for the Application ID is up to the application provider. When the Application ID has the value 0 this is used

to provide the system with information about which services are carried in this data channel. This is fully

The remaining 11 bits define the block length which permits block lengths of up to 2 048 bytes long.

The network operator packs the available data into the Teletext packets. He has to read the block

lengths in order to put in the Block Pointer (BP) values. The BP may point to 1 of 13 locations in a Teletext

packet according to table 3. Where a data block does not fill up to 1 of the 13 possible start locations the

free bytes are filled with Filler Bytes (FB). Filler bytes are also used to pad out the end of a packet if the

broadcaster has no data available to fill it. The benefit of this process is that each block start is not only

pointed to from the previous block length but also from the BP. It provides a robust method of

synchronizing the application data stream. Block Pointer (BP), Block Separator (BS) and Block Length

(BL) are all Hamming 8/4 coded. Even with bit errors it should be possible for the reception device to have

a high confidence that it is in correct synchronization. The BL may not point precisely to the next BS as

these may only be placed in every third byte, when pointed to from the BP. The existence of the FB

Where the Service Operator provides very short data blocks it is possible that 2 blocks may commence in

the same Teletext Packet. Where this occurs the BP shall point to the first BS. The