MiniRDS

This is the world's first open-source RDS2 encoder!

This program is designed for generating a realtime RDS signal. It is capable of RDS2 using up to 3 additional subcarriers.

This is based on the RDS encoder from Mpxgen, which is currently not maintained.

This software is currently used as the RDS encoder for KPSK in Los Angeles, CA, USA.

Features

• Low resource requirements
• Support for basic RDS data fields: PS, RT, PTY and AF
• RDS items can be updated through control pipe
• RT+ support
• RDS2 support (including station logo transmission)

To do

• Threading

Planned features

• UECP
• Configuration file

RDS2 image reception in action: https://www.bitchute.com/video/sNXyTCCAYA8l/

Build

For Debian-like distros: sudo apt-get install libao-dev libsamplerate0-dev to install deps.

Once those are installed, run

git clone https://github.com/Anthony96922/MiniRDS
cd MiniRDS/src
make

How to use

Simply run:

./minirds

to confirm proper operation.

Please see -h for more options.

Stereo Tool integration

The following setup allows MiniRDS to be used alongside Stereo Tool audio processor.

.-------------.
| Stereo Tool |--(FM MPX w/o RDS)-----.
'-------------'                       |
                                      v
                           .-----------------------.
                           |       ALSA dmixer     |
                           | slave: MPX sound card |--------(to sound card)-------->
                           |        192 kHz        |
                           '-----------------------'
                                      ^
.---------.                           |
| MiniRDS |--(RDS output)-------------'
'---------'

First, add the following contents to ~/.asoundrc:

# ST MPX output
pcm.mpxmix {
  type dmix
  ipc_key 1001
  slave {
    pcm "digital-out" # change to your actual sound card
    rate 192000
  }
}

Next, add the collowing contents to ~/.ao:

dev=mpxmix

Then set the Stereo Tool MPX output to use the ALSA "mpxmix" output. Finally run minirds. Adjust volumes accordingly.

Note that this setup is not optimal. Hans plans to add RDS2 passthough to the ST external RDS input. Stereo Tool forum post

Changing PS, RT, TA and PTY at run-time

You can control PS, RT, TA (Traffic Announcement flag), PTY (Program Type) and many other items at run-time using a named pipe (FIFO). For this run MiniRDS with the --ctl argument.

Scripts can be written to obtain and send "now playing" text data to MiniRDS for dynamic RDS.

See the command list for a complete list of valid commands.

RDS2

MiniRDS has a working implementation of the RFT protocol in RDS2. Please edit the Makefile accordingly and rebuild for RDS2 capabilities. You may use your own image by using the provided "make-station-logo.sh" script. Valid formats are PNG or JPG and should be about 3kB or less. Larger images take considerably longer to receive.

References

• EN 50067, Specification of the radio data system (RDS) for VHF/FM sound broadcasting in the frequency range 87.5 to 108.0 MHz
• IEC 62106-2, Radio data system (RDS) – Part 2: Message format: coding and definitions of RDS features
• IEC 62106-3, Radio data system (RDS) – Part 3: Usage and registration of Open Data Applications (ODAs)
• IEC 62106-4, Radio data system (RDS) – Part 4: Registered code tables
• IEC 62106-6, Radio data system (RDS) – Part 6: Compilation of technical specifications for Open Data Applications in the public domain
• P232 RDS Encoder Technical Manual

Credits

The RDS waveform generator was adapted from PiFmRds