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Acoustic Modem
HydroAcoustic Remote Controller (HARC)
High Precision Timing Reference (HPTR)

HPTR data sheet
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GPM 300 Acoustic Modem

The GPM (General Purpose Modem) 300 series acoustic modems are a compact, power efficient solution for reliable long range underwater voice and data communications at speed and depth. Applications include submarine communications, wireless command and control, data and file transfer. This modem has been proven at the deepest part of the ocean.


  • Voice communications up to 25 km and reliable MASQ digital communications up to 45 km.*

  • Data rate of 10 to 1200 baud depending on required range and power. Rate and power settings can be dynamically configured to maximise battery life.

  • Supports MASQ, the third generation L3 Oceania multi channel Direct Sequence Spread Spectrum (DSSS) technology. This has been proven at full ocean depth and in harsh, multi path, reverberating and noisy hydro acoustic environments.

  • Uses Forward Error Correction to enhance data reliability

  • Supports communication between moving platforms with a Doppler tolerance of +/-15 knots (higher rates available as an option).

  • Different housings available, from 1000 m (3,300 ft), 5000 m (16,400 ft), to full ocean depth.

  • Compact, lightweight and designed for maritime use

  • Low Probability of Intercept for covert communications

  • Microsoft Windows® command and control interface

  • Compatible with L3 Elac UT 3000 Underwater Telephone

  • Voice communication compliant with NATO STANAG 1074 UQC (Underwater Communication Industry)

    * Assumes best case sea condit ions, no environmental noise and no effects of ray bending. Actual range obtained depends on deployment characteristics, environmental noise and sea conditions.