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Data Sheet

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The Type 7986 Lightweight Release Transponder (LRT) has been developed by Sonardyne from transponders used to accurately position hundreds of seismic receiver nodes.  It has both receive and transmit functions, unlike similar low-cost release transponders, enabling accurate slant ranges to be measured, release actuation to be confirmed and its position to be determined.


The LRT, which is part of Sonardyne’s Coastal Acoustics product range, is depth rated to 500 metres, making it the ideal choice for use in continental shelf waters.  Field replaceable alkaline or lithium battery packs give a listening life of 18 months and 52 months respectively.  A ‘screw-off’ release mechanism ensures a positive release action that overcomes any biological growth and all external parts are made of high strength plastics that provide excellent corrosion resistance.


The Type 7967 surface control unit comprises a low-cost deck unit and remote transducer on 10 metres of cable.  The deck unit is initially used to program the acoustic identity of the LRT, test the transponder and load the release ‘bit’ prior to deployment.  Once deployed, the deck unit can measure ranges to the transponder and prior to sending a secure release command, relocate the transponder.  The deck unit can be controlled via RS232 enabling raw range data to be logged to a PC.


The transponder is compatible with Sonardyne’s ROV-Homer and Homer-Pro target relocation systems.  Deployed at a point of interest and weeks or years later, the LRT can be interrogated to provide range and direction guidance to a ROV pilot or diver wishing to home back on to it.


Furthermore, the transponder’s exact seabed co-ordinates can be quickly and easily determined using Sonardyne’s Prospector system, calibrated from a dGPS positioned vessel.  A rope canister is also available with 75 metres or 120 metres of rope for pop-up buoy applications.



  • Safe Working Load of 125 kg
  • Depth rated to 500 metres
  • Over 4 years deployment with long-life Lithium battery pack
  • Thousands of secure identities; field programmable with deck unit
  • Reliable, 'screw-off' release
  • Rugged, compact design
  • Compatible with Scout USBL, ROVHomer, Homer-Pro and Prospector positioning/relocation systems
  • Optional rope canister with 75 metres or 120 metres of 1200 kg breaking-strain rope


Seabed Mounting Frames

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