MAIANA ™: The Open Source AIS Transponder

Fig.MAIANA AIS transponder transmitting and receiving part with fixed antenna (Open Marine)

Peter Antypas self-built an AIS class B receiver / transmitter and presented it on Github:


The device combines the following functions:

  • AIS class B receiver / transmitter
  • 161.975 MHz (channel 87B), 162.025 MHz (channel 88B)
  • 2W transmission power
  • Silicon Labs 4463 transceiver ICs
  • STM32L412 microcontroller 80MHz
  • GPS Quectel L70R module, ceramic SMD antenna (for your own location transmission)
  • 3.3V UART output at 38.4Kbps
  • NMEA0183 data telegrams
  • Update rate 1 Hz
  • 12V / 30 mA
  • Disclosure of construction documents and the Software on Github

The AIS transponder consists of a transmitting and receiving part with a permanently attached antenna, which is connected to an adapter box via a shielded cable. The transmitting and receiving part receives and decodes the AIS signals and transmits them as NMEA0183 data stream with 3.3V voltage level to the adapter box, which can forward the NMEA0183 data stream in three different ways:

  • NMEA0183 USB output for PC or Raspi
  • NMEA0183 RS422
  • NMEA2000

There is a separate adapter box for the respective output type. A normal shielded CAT5 network cable with RJ45 plugs is used as the connection cable. In addition to receiving AIS signals, MAIANA can also send AIS signals. Since the device has no CE certification and radio approval for AIS operation, it may only be used in receiving mode in Europe. In principle, transmission is also possible, which can be switched on via a switch on the adapter box.

The AIS transponder is sold through OpenMarine. On the website, the buyer is advised that he is buying a device that is not CE certified and approved. It is the responsibility of the buyer to comply with the respective approvals in his area of use. Finally, the device must not interfere with or impair the AIS data traffic when transmitting. Otherwise it would have fatal consequences. In Europe, the reception of AIS signals is not a problem, whereas the transmission operation requires a permit. According to Peter Anypas, the legal situation in the USA is different. There you can use devices you have built yourself in transmission mode if the transmission power is limited



Fig.MAIANA AIS transponder transmitting and receiving part

Fig.Transmit and receive part (Open Marine)

(Open Marine)


Fig.Adapter board USB version (Open Marine)

Fig.Adapter USB version (Open Marine)

Fig.Adapter RS422 version (Open Marine)

Fig.Adapter CAN version (Open Marine)

Fig.AIS transponder behind radar device (Open Marine)

Fig.MAIANA AIS transponder rear mounting (Open Marine)