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Autonomous Monitoring Transponder

Engineered for: Seabed, Structure

Whether you are looking to monitor a moving subsea structure or an underwater landslide, look no further. AMTs combine accurate range and pressure measurements, onboard data logging, long deployment life and wireless seafloor-to-surface communications. Data can be even be collected in real time using a USV to harvest and deliver your information.

At a glance

Recommended for long endurance site surveys

Leave it deployed for six years or more

Extensive choice of monitoring sensors

Depth rated to 3,000 m

Harvest data using a ship, buoy, AUV or USV

Remote and precise subsea monitoring

Want to find out more?

There's a model of AMT to suit any deployment scenario

Options include units with an acoustic release built in for easy recovery (left)

Housing options include Super Duplex stainless steel (left)

AMTs in maxi housings have batteries which last many years without servicing

Benefits of AMT for your operations


It can detect subtle movement often not picked up by traditional ROV surveys so ideal for monitoring slow movements, like creeping or buckling pipelines.


Using structure and seafloor transponder buckets, AMTs can be ROV-deployed, removed and re-installed to provide insight over time.


AMTs can be configured to make measurements at specific intervals and these can be adjusted on-demand by you as your campaign progresses.


Autonomous Monitoring Transponder (AMT) is a long-endurance 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.

AMT has many of the same acoustic functions as Compatt 6, our most popular navigation transponder. It operates in the Medium Frequency (MF) band and is fully Sonardyne Wideband 2 compatible.

The instrument 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.

Why invest


  • Sonardyne Wideband 2 MF band (18 - 36 kHz)

  • Over 500 unique addresses, ideal for large array deployments

  • Data transfer rates of 100 to 9,000 bps - user selectable

  • Omni-directional and directional transducers to suit environmental conditions

  • Ranging precision: Better than 15mm


  • 3,000 m depth rating

  • Aluminium or Aluminium-bronze housing depending on environmental conditions and duration of deployment

  • Can be deployed for over 5 years without recovery (maxi housing)

  • ROV-friendly design; integrated acoustic release mechanism as standard


  • Standard onboard: Temperature, tilt, strain gauge

  • Optional onboard: High precision stain gauge, DigiQuartz pressure sensor, high accuracy inclinometer, sound velocity

  • Sampling rate: User configurable

  • Vessel, USV or AUV data harvesting options

  • Optional external: Current meters, turbidity sensors...


  • A typical system; multiple seafloor and structure mounted AMTs (typically 6), vessel-based Modem 6 or Dunker 6 or HPT 5000 / 7000, SIU, Monitor software

  • Warranty: 1 year return to Sonardyne service centre

  • ITAR Controlled: No

  • UK Export License: Not required


Feature Type 8305-3411 Type 8305-3111 Type 8305-3113
Depth Rating 3,000 m 3,000 m 3,000 m
Operating Frequency MF (20–34 kHz) MF (20–34 kHz) MF (20–34 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 193–202 dB 196–208 dB
Receive Sensitivity (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 1 & 2 >500 >500 >500
Battery Life (Listening, Disabled) 833 Days 1390 Days 833 Days 1390 Days 833 Days 1390 Days
Safe Working Load (4:1) N/A 250 kg 250 kg
Mechanical Construction Aluminium-bronze Aluminium Aluminium
Dimensions; Length x Diameter 1007 x 130 mm 1034 x 134 mm 1018 x 134 mm
Weight in Air/Water** 35 kg/24 kg 24 kg/12 kg 24 kg/12 kg
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 1350 m, 2000 m, 4130 m, 6800 m (±0.01%) Optional Optional Optional
High Accuracy Inclinometer
Range: ±90°, Accuracy: ±0.05° over 0 - ±15°; ±0.2° over 0 - ±45° Optional Optional Optional
Sound Velocity Sensor
±0.02 m/s accuracy under calibration conditions Optional Optional Optional
Release Mechanism Not Available Standard Standard

Manuals and quick start guides

Software and firmware

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Remote and precise subsea monitoring