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The Modem M64 is a two-way half-duplex 64bps acoustic modem with a robust and user configurable data link.

The M64 sets a new market standard with its record-breaking physical size, low power requirement and cost. All this combined with a very useful technical specification, the M64 opens new possibilities for underwater communication in both existing and new areas.

Key specifications

  • Two-way communication

  • 64 bit per second net data link, both ways

  • Latency 1.5 – 2.5 sec

  • 200 meter range

LED Signals

  • No green light: Power is off.

  • Flashing green light (every 3 seconds): Modem is trying to pair with another modem.

  • Fixed green light: Modem has sync with another modem. The LED will blink each time it receives a packet from the other modem (once a second).

Wiring interface

The tables below shows the pinning of the Modem-M64 interface.

Interface Color
Positive (10-18V) Orange
Negative/Ground Orange/White
UART TX Brown/White

Terminal Interface

The Modem-M64 has a 3.3 volt UART interface.

Settings Value
Baud rate 115200
Data parity stop 8N1
Flow control None


Modem M64 supports channels 1-7. Channel overveiw can be found here.

Libraries and code examples

Example code and libraries that can be used to communicate with the modem on the terminal interface: