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MicroMPX is our STL (studio-to-transmitter link) codec. It transports a full FM composite MPX signal, including pilot and RDS, at a bitrate of only 320 kbit/s, with perfect peak control. Using MicroMPX you can generate your signal completely in your studio and easily distribute it to all your transmitters.

Audio benefits

 MicroMPX is a codec that is specifically designed for FM. It doesn't cause typical lossy codec artifacts (pre/post ringing, watery sound), and perfectly maintains peak control, even when using composite clipping. This eliminates the need to have an expensive high end audio processor or stereo/RDS generator at the transmitter site.


MicroMPX has built-in error correction for connection drops, and supports dual paths (you can send the same data over multiple connections, as long as any of them arrive the audio keeps playing). If everything fails, there's a built-in backup audio player.

Easy monitoring

With MicroMPX, you can add destinations to monitor the audio remotely, for example at home, or send it to someone who is adjusting your processing. The signal is identical to what's going out to the transmitters. The MicroMPX decoder has a built-in demodulator and left/right output, allowing you to listen to the stereo demodulated audio.

How do I use it?

Place the encoder (which can be our software encoder, or the encoder built into Stereo Tool, the Omnia.9, Omnia MPX Node or 2wcom encoder) in your studio, and decoders (which can again be our software decoder, the Omnia MPX Node or 2wcom decoder) at your transmitter site. Fill in the IP addresses of all decoders in the encoder. Finally, adjust the levels at your transmitter sites to match the required modulation level and you're done.

SFN: GPS synchronization

Identical MicroMPX receivers that are fed by the same encoder are typically in sync within a few milliseconds, which is good enough for RDS AF switching. If you have a Single Frequency Network (SFN) with multiple transmitters that are broadcasting at the same frequency with overlapping reception areas, with GPS synchronization the decoders can be synchronized to within less than 1 µs.


Hardware requirements

MicroMPX can run on any somewhat recent pc, and even on a Raspberry Pi 2, 3 or 4. Many stations choose to run it on a Raspberry Pi with HifiBerry sound card, due to the small form factor, stability and low price. The total hardware costs for this are around 100 euro (close to $100).

 We have a ready-to-go Raspberry Pi 2/3/4 + HifiBerry image available for download on our site. Just write it to an SD card, put that SD card in your Pi + HifiBerry and you're good to go.

Alternative hardware

There are other manufacturers that support MicroMPX. Here are some hardware units that support it (sometimes as an upgrade, so please verify that it does what you need before you buy).

Encoders and decoders

Transmitters with decoders built in


All features

MicroMPX Decoder

- Decodes a full MPX composite signal at bitrates down to 320 kbit/s
- Supports error correction
- Supports redundant connections
- Supports multicast/broadcast connections

MicroMPX Encoder

- Encodes a full MPX composite signal at bitrates down to 320 kbit/s
- Supports error correction
- Supports redundant connections
- Supports multicast/broadcast connections