Looking at the different types of RDS Frames

The RDS Frame Types

The frame structure is common to all group types.

Each coding structure follows a common format for each group type. Block 1 and Block 2 are the same for each group. Whereas Block3 and Block 4 have group specific data. The possible group types are:

Group Type	Description	Group Type	Description
0A	Tuning and switching information	0B	Tuning and switching information
1A	Program Item Number (PIN) and slow labelling codes	1B	Program Item Number (PIN)
2A	Radio Text	2B	Radio Text
3A	Application Identification (AI ODA)	3B	Open Data Application (ODA)
4A	Clock (Date, Time) Information	4B	Open Data Application (ODA)
5A	32 Transparent Data Channels or ODA	5B	32 Transparent Data Channels or ODA
6A	In House or ODA	6B	In House or ODA
7A	Radio Paging or ODA	7B	ODA
8A	Traffic Message Channel (TMC) or ODA	8B	ODA
9A	Early Warning System (EWS) or ODA	9B	ODA
10A	Program Type Name (PTM)	10B	ODA
11A	ODA	11B	ODA
12A	ODA	12B	ODA
13A	Enhanced Radio Paging (ERP) or ODA	13B	ODA
14A	Enhanced Other Network Information	14B	Enhanced Other Network Information
15A	Fast Switching Information	15B	Fast Switching Information

This basic encoder uses few of these groups, essential 0, 1, 2, 4, 10. Here is an example of the group 2A internal format:

The group 2A is used for sending Rich Text of up to 64 bytes but only 4 bytes can be sent per group so the complete text has to be sent in a sequence of up to 16 groups. If the sequence has < 64 bytes it can be terminated at any time by a CR character. Also there must be at least 3 x 2A groups per second.

Thus (see diagram) TF is the A/B group flag and T3..T0 are the sequence numbers, eg: 0x8000 is for bytes 33, 34, 35, 36.

Having covered the basics, the next part shows how the groups are chained to get a super block then converted to symbols.

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