3 ‐ Other functions and RDS services
This section allows you to view the AF list(s) sent by the station you are listening to.
The AF function allows receivers (mainly car tuners) to automatically switch to other frequencies of the same station, ensuring optimal reception for the listeners.
When the signal becomes weak and difficult to hear, the car tuner can switch to another frequency on the network, provided that it is in the list.
This is particularly useful when driving, allowing for seamless switching between the different transmitters used by the station.
RDSExpert is able to display these frequency lists, indicating the type of method used (A or B), but also the number of expected frequencies (the number sent at the beginning of the list), and the number of decoded frequencies. This allows the user to know if all the frequencies in the AF list have been decoded.
The head of list ("Master" frequency) appears in a blue box as soon as it is decoded.
By default, the list is displayed as configured by the broadcaster. This means it may not always be in the correct order.
To automatically sort the frequencies and thus ignore the order configured by the engineer on the RDS encoder, you can click the Frequency Sorting button.
Method A is technically limited to 25 frequencies. Method B allows to transmit much more, in the form of multiple lists with different "master" frequencies.
The display in the decoder varies depending on the method used, for these reasons.
RDSExpert can display LW and MW frequencies, if they are present in the Method A list of the decoded RDS.
In this case, these frequencies are displayed in purple boxes.
For Method B lists, frequencies with a regional program indicator are displayed with the mention "[REG]".
In the following example, showing a Method A list, all expected frequencies were successfully decoded:
Here, we have a Method B list with the "regional program" indicator on all frequencies:
This section allows you to view the EON list sent by the station you are listening to, if this function is enabled, with its complete content.
The EON function allows car tuners to monitor other stations, usually part of the same network as the one being listened to, in order to switch more efficiently to one of them when a traffic announcement is aired.
RDSExpert has the ability to display a list of stations present in the EON configuration of the station being listened to, along with their PI codes.
By clicking on one of the lines, you can see the mapped frequencies and the Method A AF (If this function is used).
The tool also allows you to view Linkage and PTY information, whether the TP and TA flags are enabled, and whether a PIN value is being transmitted.
The number of stations found in the EON list is indicated at the top of the section. Underscores on the PS fields represent spaces.
The Groups Monitor section allows you to view the live transmission activity of the different RDS groups.
Click Start to begin scrolling through the different groups, along with percentage statistics that show whether a group is transmitted more frequently than others.
The percentage is accompanied by the number of packets per group, which can be easily compared to the total number of decoded packets.
You can easily find out what a group is for by placing your mouse cursor over it. A tooltip will appear with a description.
If an ODA application is detected on group 3A, a message appears at the top of the Groups Monitor window with the service ID, its 4-character code, and the group to which this data is being sent.
RDSExpert has an official database of approximatively 70 different codes, allowing it to recognize different ODA applications based on the code sent by group 3A. The tool can also display the code of an application that is not recognized (If it is not present in the database).
Slow Labelling Codes (SLC) are also displayed if sent on group 1A.
Clicking the Show Groups Content button allows you to view the content transmitted on a particular group in binary and ASCII formats.
Select the group you wish to monitor from the list, you should see the rows scroll by. Only one group can be monitored at a time.
If you wish to save time, you can also directly click on a group in the "Group Distribution Statistics" section to be redirected to the monitoring panel for that group.
Clicking the Show Hex Values button displays the values transmitted for up to four groups simultaneously, in hexadecimal format. To change the monitored group in each column, simply click on the header group and replace it with the desired group.
You can pause, reset, or stop the display at any time.
By clicking the button next to "Group Distribution Statistics", you can access a representation of the group distribution in the form of graphs (Pie chart and bar charts).
This allows you to clearly visualize how the groups are sent, which ones are favored, and which ones are not.
By placing your mouse cursor over one of the decoded groups, you will be able to see its distribution percentage.
Here are some examples of groups commonly sent over RDS:
| Group | Utility / Function |
|---|---|
| 0A | This is the most common group: It transmits the PI code, PS, PTY, TP/TA/MS flags and the AF list. |
| 1A | Sends ECC (Extended Country Code) and LIC (Language Indication Code) information, which allows identification of the country from which the station broadcasts as well as the language in which its programs are broadcast. It is also used to send PIN values. |
| 2A | Transmits Radiotext: Often used to display a slogan or the title of the song being aired by the station, as well as useful information for the listeners. |
| 3A | Sends the list of the ODA applications being used: Allows the receiver to identify which ODA applications are used by the station (The most common examples are Radiotext+ and TMC), if the station uses any. |
| 4A | Clock Time (CT) : Transmits the date and time in order to synchronize the receivers clock, most often car tuners. This group is generally transmitted every 60 seconds, at the beginning of each minute. |
| 10A |
PTYN: Equivalent to PTY, but in a completely customized way as previously indicated in this documentation. |
| 14A |
EON (Enhanced Other Networks): See the indications mentioned above in this documentation. |
| 15A |
Long PS: Allows a longer PS to be displayed, up to 32 characters, than the standard sent on group 0A which only permits 8 characters. |
Groups 5A, 6A, 7A, 8A, 9A, 11A, 12A and 13A are free and generally used to transmit information related to Open Data Applications (ODA).
Less frequently, and depending on the station, these same groups may have a "B" variant (0B and 2B, for example).
This section displays Radiotext+ tags detected on an RDS station and their contents
The Radiotext+ function enhances interactivity by displaying information sent on the Radiotext (RT A and RT B) separately.
For example, if a station displays the name of song it currently airs, Radiotext+ can retrieve the artist and song titles and display them separately.
This improves the display of this information on certain compatible car tuners.
This function is not limited to this type of information: 63 different tags exist (For example, "Website/URL" or "SMS: Studio").
All of these tags can be recognized by RDSExpert thanks to an integrated database, which displays the tag type, its content, and its identification number (From 1 to 63).
RDSExpert has a cache function for Radiotext+, meaning that the decoder memorizes all tags and their content and can display them even when they are not currently transmitted.
This is a handy way to ensure you don't miss a single one. In this case, the tag type is accompanied by the CACHED indicator, which disappears again as soon as the tag is transmitted again.
The Radiotext+ section also includes a real-time display of the Item Running and Item Toggle bits usage.
If these bits are being sent, the display lights up green.
This section allows you to decode and analyze the TMC data sent, if the station you are listening to offers this service.
Note: This decoder was implemented on a purely experimental basis.
If the TMC service is available on the radio station being listened to, the SERVICE DETECTED indicator will light up. You can begin decoding the data by clicking the START button.
Although this technology is becoming increasingly deprecated and is being phased out in Europe, some countries still use it.
For example, as of December 10, 2025: The United Kingdom still sends this type of data through the Classic FM network, and Germany also sends this information on the ARD network stations.
The information displayed on the screen consists of the various traffic information events sent through the TMC service, with details if available (e.g. Road closures, congestion, accident, etc.). About 1500 types of events can be recognized and decoded.
To preserve the web browsers performance, the display limit of unique messages/events is set to 500.
The decoder includes an update counter that increases each time a message is sent for the same event.
A raw location code is also displayed. It is not possible to know precisely where the event is located, as this would require access to a TMC database maintained by important companies, which is generally not freely available to the public.
The TMC decoder displays details about each event, such as CC and LTN codes, the type of emergency, the nature of the alert, its duration, etc.
