Sonardyne Autonomus Monitoring Transponder (AMT)

The Type 8305 AMT is a long-endurance Compatt 6 based transponder that is extensively used for subsea survey tasks and is capable of autonomously acquiring acoustic ranges and sensor data without surface control.



The data is time-stamped and logged internally for recovery via the integrated high-speed acoustic telemetry modem. This autonomy allows measurements to be made over a long period of time without requiring a surface vessel or ROV to command the process. This enables new applications that save vessel and survey time so reducing cost and risk.

Precision pressure, temp, sound velocity and dual-axis inclinometer sensors are integrated and are intelligently powered up at the requested time and sampling period, providing an ultra-low power platform for up to three years deployment. Sampling regimes can be re-programmed and recovery of all data can be achieved via the acoustic telemetry link.

The Autonomous Monitoring Transponder has many of the same acoustic functions as Compatt 6. It operates in the Medium Frequency (MF) band and is fully Sonardyne Wideband®2 compatible.

The AMT is available with a range of omni and directional transducers, depth ratings and pressure housings dependent on deployment duration and application. Additional external sensors can be easily integrated via the power and communications port.

  • Recommended for long endurance site surveys
  • Leave it deployed for six years or more
  • Extensive choice of monitoring sensors
  • Depth rated to 3,000 metres
  • Harvest data using a ship, buoy, AUV or ASV

Technical information

Feature Type 8305-3411 Type 8305-3111 Type 8305-3113
Depth Rating 3,000 Metres 3,000 Metres 3,000 Metres
Operating Frequency MF (18–34 kHz) MF (18–34 kHz) MF (18–34 kHz)
Transducer Beamshape Omni-Directional Omni-Directional Directional
Transmit Source Level (dB re 1 µPa @ 1 m) 187-196 dB (4 Levels) 187-196 dB (4 Levels) 190-202 dB (4 Levels)
Tone Equivalent Energy (TEE)* 193-202 dB (7 levels) 193-202 dB (7 levels) 196-208 dB (7 levels)
Receive Sensivity (dB re 1 µPa) 90-120 dB (7 levels) 90-120 dB (7 levels) 80-120 dB (7 levels)
Ranging Precision Better Than 15 mm Better Than 15 mm Better Than 15 mm
Number of Unique Addresses (Wideband) >500 >500 >500
Battery Life (Listening, Disabled) 833 Days (Alkaline)
1390 Days (Lithium)
833 Days (Alkaline)
1390 Days (Lithium)
833 Days (Alkaline)
1390 Days (Lithium)
Safe Working Load (4:1) N/A 250 kg 250 kg
Mechanical Construction Aluminium-Bronze Aluminium Aluminium
Dimensions; Length x Housing Diameter 1007 mm x 130 mm 1034 mm x 134 mm 1018 mm x 134 mm
Weight In Air/Water** 35 kg/24 kg 24 kg/12 kg 24 kg/12 kg
End Cap Sensors and Options
Temperature (±0.1°C) Standard Standard Standard
Tilt Switch (±30-45°) Standard Standard Standard
Strain Gauge Pressure Sensor (±0.1%) Standard Standard Standard
High Precision Strain Gauge (±0.01%)·
Presens or Keller
Optional Optional Optional
Paroscientific DigiQuartz Pressure Sensor (±0.01%)
1350 m, 2000m, 4130 m, 6800 m
Optional Optional Optional




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