What are Acoustic Releases & Acoustic Transponders?

An acoustic release is a remotely operated mechanical hook controlled through the water column and using acoustic waves communication channel. It is mainly used to recover instrumented mooring lines or subsea structures, as well as for deploying payloads on the seabed (ie. For marine construction, or cable laying….).

An acoustic release is mainly made of the following elements:

1. The transducer (also named acoustic head) relies on the piezoelectric effect of a ceramic ring in order to convert acoustic waves into electrical signals and vice-versa.
2. The watertight housing of an acoustic release is designed to provide mechanical resistance and corrosion prevention depending on the deployment depths and length.
3. The electronic board should feature ultra-low power consumption to provide long battery life (hence, long deployments) to the acoustic release.
4. The type of battery pack (alkaline or Lithium) will be chosen depending on the required deployment duration.
5. The gearmotor actuates the release mechanism upon receipt of an acoustic order.
6. The release mechanism is sized to withstand a maximum safe working load and release load.

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An acoustic transponder is a positioning beacon that is accurate in time. It uses acoustic signals to communicate with a USBL or LBL system and operates in a frequency band selected according to the expected operational range.

An acoustic transponder is mainly used for controlling the navigation of subsea vehicles (ROV, AUV…) through a surface positioning system and to build an array of calibrated beacons for subsea navigation.

An acoustic transponder is mainly made of the following elements:

1. The transducer, operating either in Low (8-18 kHz) or Medium (20-30 kHz) frequency range, relies on the piezoelectric effect of a ceramic ring in order to convert acoustic waves into electrical signals and vice-versa.
2. The watertight housing is designed to provide mechanical resistance and corrosion prevention depending on the deployment depths and length.
3. The electronic assembly detects and transmit positioning signals, and manages potential sensors when available.
4. The type of battery pack (alkaline or Lithium) will be chosen to provide the highest number of acoustic responses.
5. The release mechanism, associated to a gearmotor, is sized according to the expected safe working load and release load that will be deployed and recovered.