Low Frequency Active and Passive Variable Depth Sonar

An unrivalled performance against quiet submarines to achieve any anti-submarine warfare missions including escort, area sanitization and own force protection.

  • Ultra long range
    Capable of very large detection in every environmental condition.
  • Reduced operator workload
    The only large VDS to provide automated deployment and recovery procedures without operator on aft deck.
    The lowest operating and training manpower for this class of system.
  • Cooperative asset
    Very accurate target positioning to prosecute and engage distant submarines with airborne assets.
    Multi-static capability with virtually all low frequency sonar in operation world-wide.
    Minimising interference with other VDS and BMS
  • Embedded torpedo defence
    Permanent self defence capability.
  • Mammals safe
    Adjustable source level & noise monitoring for sea mammal protection.
  • Low Life Cycle Cost

Large installed base and continuous evolutions for Inherent customer’s long term support.


CAPTAS family

  • The only LFA VDS in service in NATO countries
  • More than 40 CAPTAS systems already ordered
  • 2 installation variants for CAPTAS 4:
    • T23 UK frigate
    • FREMM frigate


Selected by:

  • French Navy (CAPTAS-4 on FREMM)
  • Italian Navy (CAPTAS-4 on FREMM)
  • Royal Malaysian Navy (CAPTAS-2 on SGPV LCS)
  • Royal Moroccan Navy (CAPTAS-4 on FREMM)
  • Royal Norwegian Navy (CAPTAS-2 on NNF)
  • Royal Saudi Navy (CAPTAS-2 on F4000)
  • UAE Navy (CAPTAS-2 on Abu Dhabi)
  • UK Royal Navy (CAPTAS-4 on T23)

CAPTAS-4 selected by the US Navy for ADM contract on LCS programme.


A rugged design for sea operations which allows the ASW units to transmit and receive at the right depth with two separate arrays and maximize the detection of extremely quiet submarines.
The system is designed to independently deploy the arrays at optimum depth to continuously survey 360 degrees with a well covered water column, thus overcoming harsh propagation conditions and surface-layer problems inherent to Hull Mounted Sonar.


System features:

  • For platforms > 3000T
  • In operation since 2004
  • Operated from CMS Multi-Function Consoles
  • Two winches to independently deploy/tow the transmit towed body and the receive array
  • Bottom safety warning function
  • Integrated On-Board-Training capability
  • Performance prediction function for sonar optimisation
  • Passive and active sonar track association
  • State of the art adaptive signal processing
  • Comprehensive Built-in Test capability
  • Cutting edge technology employees due to continuous product upgrade


Transmit array features:

  • Highest Source Level for this type of sonar due to its 4 Free Flooded Rings antenna
  • 360° bearing omni-directional transmission
  • Low reverberation effect, due to its vertical directivity
  • Optional underwater telephone capability


Receive Triplet Array Features:

  • Instantly resolves right/left ambiguity issue


Active Frequencies: below 2kHz
Bandwidth: Wide FM
Pulse lengths: up to 16s
Pulse Modes: FM, CW and COMBO
Operational limits: Up to sea state 6
Operating depth: Up to 230m depth, e.g. 180 m at 12knts
Detection performance: Up to second oceanic Convergence Zone