ahoi -Underwater acoustic modem

Founding developers Christian Renner, Jan Heitmann, and Fabian Steinmetz

Accessories for ahoi -Underwater acoustic modem

Founding developers Christian Renner, Jan Heitmann, and Fabian Steinmetz

Christian Renner leads the Institute for Autonomous Cyber-Physical Systems at Hamburg University of Technology (TUHH), Germany. Jan Heitmann and Fabian Steinmetz have been a member of his team. His research aims at energy harvesting and networking aspects, and mobile underwater swarm robotics with a special focus on underwater acoustic communication and localization.

The ‘ahoi -underwater modem’ is a wireless networked sensing device that is integrated into micro autonomous underwater vehicles (µAUV). Underwater communication is a mandatory requirement as enabling technology. For this, only acoustic communication is suitable since radio waves suffer from heavy absorption in water, and poor visibility exclude optical approaches. The 'ahoi -underwater modem' is the only acoustic modems that can easily be integrated into the µAUVs.


μAUVs enable automated, unsupervised environmental underwater monitoring, inspections, and interactions with the environment. Applications range from automated water-quality monitoring over inspections of bridges and wind parks, to supporting divers in dangerous missions.

ahoi - has been used for:

  • The timely detection of health hazards for the public
  • Bio-hazards caused by fuel-oil leaks
  • Pollutant introductions by ships or industrial equipment,
  • Examination of ship hulls and sheet piles
  • Disaster management support


    • Low power consumption
    • Communication up to 200m
    • Communication range of factor 2.7 or 8dB depending on baseline consumption
    • Gain ranges from 60dB to 96dB at more than 100m
    • No signal clipping at around 2m with the lowest gain level
    • Sinusoidal signals from 0kHz to 500kHz
    • Mainboard power consumption from 195mW to 205mW
    • Receiver power consumption 99mW in sampling mode and 0.2mW in sleep mode
    • Transmitter power consumption 1mW in sleep mode and 791mW in sampling mode
    • Total power consumption of 1.1W (low output) to 2.1W (high output)
    • Processing speed of 12ms


    • Mainboard PCB (blue)
    • Receive filter and amplifier PCB (green)
    • High-power transmit amplifier PCB (red)

    Not included:

    • Wiring
    • Battery
    • Sensors 


    The lead-time for fulfillment is approximately 4 weeks from the date of ordering.


    B.-C. Renner, J.Heitmann, F.Steinmetz (2020). ahoi: Inexpensive, Low-power Communication and Localization for Underwater Sensor Networks and µAUVs ACM Transactions on Sensor Networks Vol. 16, No.2


     Documentation Source Code

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