Water Linked M64 Acoustic Modem


The Modem M64 is a two-way half-duplex 64bps acoustic modem for wireless underwater communication with 200 meter (660 foot) range and user configurable data link. With a well-documented communication interface and Python library, it’s well suited for use on AUVs, remote sensors, and autonomous vehicles.

In stock

SKU: WL-11003-1
HS Code: 8512.30.30

Product Description

The Water Linked M64 Acoustic Modem is a two-way half-duplex 64 bps underwater acoustic modem with a robust and user configurable data link, enabling wireless underwater communication. The operating principles can be found on the Water Linked website: Underwater Communication.

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

The Modem M64 has the following key specifications:

  • Two-way communication
  • 64 bit per second net data link, both ways
  • Typical latency ~500ms
  • 200 meter range

Typical Applications:

  • AUV telemetry
  • ROV wireless control
  • Autonomous vehicle research
  • Wireless subsea sensors
  • Research projects
  • Any scenario where you need to wirelessly control and monitor subsea equipment

Key Features:

  • Omnidirectional operation which will keep the data link stable even when the modem is in motion and/or being rotated around its axes.
  • Fully self-contained with no requirements for external computers, top-side controllers or other devices.
  • Packet based protocol with extensive use of error detection to enable a highly robust transmission.
  • The integrated status LED makes it easy to confirm that the communication link is established and when data is transferred.
  • Serial 115200 baud UART 3.3V interface makes the M64 easy to integrate with other subsea equipment like sensors, ROVs, and AUVs.
  • Easy to use API to transmit/receive packages etc.
  • Can be used in a setup where one modem transmits and receives while many other modems receives.
  • Can operate simultaneous with Underwater GPS.
  • Extremely small size enabling easy integration in other equipment.
  • Very low power consumption.
  • Highly robust operation, also in areas with acoustic reflections (shallow water, around installations etc.)


  • 1 x Modem M64


Range200 m656 ft
Frequency100-200 kHz
Data Rate through Water64 bit per second, both ways
ProtocolSerial UART
Baud Rate115200
Data Buffer1 MB
Supply Voltage10-18 V
Serial Voltage Out3.3 V
Peak Current216 mAh at 12V
Cable Length2 m 78 in
Length112 mm4.41 in
Diameter30 mm1.18
Weight (in air)128 g4.51 oz
Depth Rating300 m984 ft
Body MaterialPEEK
Operating Temperture-5 to 60 °C23 to 140 °F

Wiring Interface

Positive (10-18V)Orange
UART TXBrown/White

Terminal Interface

The Modem-M64 has a simple 3.3 volt UART interface.

Baud rate115200
Data parity stop8N1
Flow controlNone


Modem M64 Datasheet (PDF)

Revision History

11 July 2019

  • Initial Release

Libraries and Code Examples

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


Modem-M64 Protocol

Protocol Specifications (Water Linked Documentation)

LED Indicator

  • No green light: Power is off.
  • Flashing green light (slow): 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.


Blue Robotics Forum – Water Linked Acoustic Products

Water Linked Forum – Acoustic Communication