IEC 62106-2:2018 pdf download

IEC 62106-2:2018 pdf download.Radio data system (RDS) – VHF/FM sound broadcasting in the frequency range from 64,0 MHz to 108,0 MHz
4 Message format
4.1 Design principles The basic design principles underlying the message format and addressing structure are as follows: a) The original single RDS data-stream (now referred to as data-stream 0) has been supplemented by three new RDS data-streams referred to as data-streams 1 , 2 and 3. Data-stream 0 will continue to only carry group types A and B (referred to as legacy data). Data-streams 1 , 2 and 3 will only carry a new group type C. Legacy data groups A and B can be carried on data-streams 1 , 2 and 3, but first need to be packaged within a type C group using a mechanism referred to as “tunnelling”. b) The mixture of different kinds of messages within any type A or B group is minimized. For example one group type is reserved for basic tuning information, another for RadioText, etc. This is important so that broadcasters, who do not wish to transmit messages of certain kinds, are not forced to waste channel capacity by transmitting groups with unused blocks. Instead, they are able to repeat more frequently those group types which contain the messages they want to transmit. c) Data that has to be acquired quickly for receiver operation and for which a short acquisition time is required, for example Programme Identification (PI), Programme Type (PTY), and Traffic Programme flag (TP) are transmitted frequently and are always transmitted in data-stream 0. In data-stream 0, these features are present in every group and occupy the same fixed positions. They can therefore be decoded without reference to any block outside the one which contains the information.d) The Programme Service name (PS), a fundamental feature of RDS, is also always transmitted in data-stream 0, using a fixed group type – 0A or 0B for the short form, 1 5A for the longer (UTF-8) form. By having a fixed group type (i.e. not an ODA), the PS name can be decoded without reference to any other group. e) For compatibility with existing receivers, other RDS features will continue to use fixed group types and be transmitted in data-stream 0. These include Slow-labelling (1 A), Clock-time (4A), RadioText (2A or 2B), PTYN (1 0A), EON (1 4A and 1 4B) and TA status control bursts (1 5B). f) The practice of allowing future applications to be defined by using an Open Data Application has been extended, and the data formatting has been made more flexible. In addition to an Open Data Application (see IEC 621 06-3) using legacy group types A or B in data-stream 0 (see Table 2), a new group type C Open Data Application has been specified to allow greater data capacity in data-streams 1 , 2 and 3. g) Open Data Applications defined by group types A or B can be carried in any data-stream 1 , 2 and 3, although use of data-streams 1 – 3 requires the use of tunnelling. h) Open Data Applications defined by group type C can only be carried in data-streams 1 , 2 and 3. The essential core RDS features (PI, PTY, PS, etc.) will always be transmitted in data-stream 0 in every programme service using group types A or B. i) The application identification AID which identifies an Open Data Application shall be sent at least once every 5 seconds.
4.2 Group structure
4.2.1 Group type A structure The group type A structure is illustrated in Figure 1 . The main features are the following. a) The first block in every group always contains a Programme Identification (PI) code. b) The first four bits of the second block of every group are allocated to a 4-bit code which specifies the application of the group. Groups will be referred to as 0 to 1 5 according to the binary weighting A 3 = 8, A 2 = 4, A 1 = 2, A 0 = 1 . For each group (0 to 1 5) two ‘versions’ can be defined. The ‘version’ is specified by the fifth bit (B 0 ) of block 2 as follows: B 0 = 0: Defines group type A. The PI code is inserted in block 1 only. This will be called version A, for example group type 0A, 1 A, etc. B 0 = 1 : Defines group type B (see 4.2.2). c) The Programme Type code (PTY) and Traffic Programme identification (TP) occupy fixed locations in block 2 of every group. Within the group type A structure, the PI, PTY and TP codes can be decoded without reference to any block outside the one that contains the information. This is essential to minimize acquisition time for these kinds of messages and to retain the advantages of the short (26-bit) block length.