MicroMPX
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.
Manual (PDF) - Running MicroMPX on a Raspberry Pi
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.
Reliability
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.