Naval Physical and Oceanographic Laboratory (NPOL) , Kochi is one of the major R&D laboratories of Defence Research and Development Organisation (DRDO). It was setup in 1952 as an in-house laboratory of the Indian Navy, then called as Indian Naval Physical Laboratory (INPL), for providing scientific support to the armed services. Later it got re-christened as NPOL after the formation of Defence Research and Development Organisation (DRDO) under Ministry of Defence in 1958. Today NPOL stands out with great pride for its outstanding achievements and contributions in the areas of SONAR research and development for Navy.

The core competence of NPOL is in the areas of oceanography, electro-acoustic transducers, signal processing and systems engineering. Commencing with Advanced Panoramic Sonar Hull Mounted (APSOH) in 1983, NPOL has delivered several sonar systems, such as Panchendriya, Humsa, Mihir etc. which have been fitted on to submarines, surface ships and airborne platforms of Indian Navy.

Over the years, the institute has established several infrastructure facilities for carrying out Defence R&D activities related to sonar systems.

INS Sagardhwani

NPOL/DRDO owns a marine acoustic research vessel named as INS Sagardhwani. It was indigenously built at M/s Garden Reach Shipbuilders and Engineers Limited (GRSE), Calcutta and commissioned in 1994. The vessel is run and maintained by the Indian Navy for DRDO and based at Southern Naval Command, Kochi.

This ship has got many special facilities for conducting underwater ocean environmental and acoustic experiments both in shallow and deep waters. State-of-the-art equipments are fitted onboard in order to pursue research in ASW oceanography and acoustics. The ship's laboratories house all relevant scientific equipment to make high resolution oceanographic and acoustics measurements at the sea. The ship can moor oceanographic and acoustic buoys in shallow and deep waters.


  • Bow and stern thrusters - better maneuverability.
  • Reverse osmosis plants-30 ton fresh water/day.
  • Minimum radiated noise.
  • Antivibration mounts for machinery.
  • Wooden quarter deck.
  • Doctor & mini operation theatre.
  • Helipad - helicopter operations.
  • Inflated boat.
  • Handling Gears for fast & safe deployment of scientific systems.Bow and stern thrusters - better maneuverability.
  • Reverse osmosis plants-30 ton fresh water/day.
  • Minimum radiated noise.
  • Antivibration mounts for machinery.
  • Wooden quarter deck.
  • Doctor & mini operation theatre.
  • Helipad - helicopter operations.
  • Inflated boat.
  • Handling Gears for fast & safe deployment of scientific systems.

Underwater Acoustic Research Facility (UARF)

This lake facility has been established for calibrating & full-scale testing of underwater acoustic transducers, arrays and other sub-sea equipment like, echo sounders, velocimeters, underwater communication systems, decoys, fish finding sonars etc. It is located at Kulamavu (100 km away from Kochi) at Idukki reservoir in the high-ranges of western ghats.

Major Capabilities

  • Three vessels: M.V. Kolumban (a barge), F.P.Kuravan ( a floating platform) and M.V. Jalaprayog (a motorboat).
  • Crane and chain-pully systems on board the barge for lifting and deploying heavy transducer arrays for making measurements.
  • A turn-table is provided for making directivity measurements.
  • Electrical power from shore-supply points.
  • Diesel generator sets of 5 kVA, 15 kVA and 63 kVA.

Depending upon the depth (and range) requirements the platform can be positioned anywhere in the reservoir and measurements can be made.

Materials and Transducers-Simulated Test Centre (MATS)

The Materials and Transducers-Simulated Test Centre (MATS) available at NPOL, is the only one of its kind in Asia-Pacific region and one of the very few in the entire world. MATS is designed for undertaking any static or dynamic measurements/evaluation/calibration of any materials or sensors/ transducers for undersea use. It can be gainfully used by a variety of people doing research in the areas of oceanography, ocean acoustics, marine geophysics, underwater acoustic transducers or any other areas dealing with undersea equipment like underwater cameras. Static as well as dynamic calibration of transducers and other sensors can be efficiently carried out under controlled pressure and temperature conditions. MATS provides three pressure chambers of different sizes to cater for various types of measurements that are required to be simulated for ocean environment. It is also designed for measurements at different operating frequencies.

The entire system of complex operations involving cooling, heating, pressurization and de-pressurisation is controlled by a distributed control system (DCS), which is virtually the brain behind the entire system operation. The system is housed at a spacious central control room.


  • Anechoic Chambers
    • Cylindrical section closed with hemispherical ends
    • Acoustic wedges for internal lining
    • 8000 mm (L) X 3000 mm (ID)
    • Two Ports - 830 mm & 500 mm (ID)3250 mm separation
    • Azimuth positioner
  • Low Frequency Tubes
    • Seamless tubes
    • Internal surface honed in single direction without any step
    • Tube 1 : 2000 mm (L) X 300 mm (ID)
    • Tube 2 : 7000 mm (L) X 200 mm (ID)

The operational sequences are built into the DCS using suitable software. All process variables are monitored and controlled from the control room using it. The control valves, drives and solenoid valves are operated from the DCS. Individual sequences and programming are implemented in the DCS for achieving the required simulated conditions inside the chambers.

Acoustic Tank Facility

This facility is for digital calibration of underwater acoustic transducers used in sonar systems and other under-water applications such as ocean bottom profiling, underwater telephony, fish finders etc. A water tank of 12 X 7.5 X 6 m size, a positioning system and a set of sophisticated instrumentation constitute this facility. It is situated at Naval Base, Kochi. Special techniques have been employed taking into consideration various requirements of calibration principles, limitations of water medium, frequency range of operation and type of parameter to be measured.

Primary calibration measurements using reciprocity principle and dunking machine method are adopted for very low frequencies (1 to 4 Hz) whereas secondary calibration using comparison technique are adopted for higher frequencies. Frequencies higher than 4 kHz, can be covered by tone-burst method, whereas pulsed sound method and random noise calibration method are employed for lower frequencies.

Directivity pattern measurements can be made up to a resolution of 0.1 degree. High power measurements on projectors are done inside a pressurized Fibre Reinforced Plastic vessel, which is deployed into the tank on specific needs.

A pulse tube (also known as impedance tube) is used for evaluation of passive acoustic materials. It can be used for evaluation of underwater acoustic properties like, reflection, absorption, transmission etc.

Measurement of acceleration sensitivity is performed using a vibration exciter system. Devices weighing up to 100 kg can be tested in this system over a wide frequency bandwidth.

Experimental Fluid Dynamics Laboratory

The Experimental Fluid Dynamics Laboratory that was established in the year 2000 as a part of the Centre for Oceanics and Optronics (COOPS), comprises of a fluid tank (10m long X 2m wide X 1.5m deep) where experiments on stratified fluids with state-of-art instrumentation can be carried out. A computer controlled mechanized trolley capable of taking payloads up to 250 kg enables scientists to conduct controlled experiments. The fluid dynamics resulting from the controlled experiments inside the wave tank can be photographed through a perspex window on the side of the tank. The facility can also be used for conducting calibrations of various instruments under controlled conditions.

Some of the typical studies taken up in this laboratory are:

  • Surface manifestations of hydrodynamic features generated by scaled models
  • Sub-surface hydrodynamic features in stratified fluids
  • Stratified wake / wave studies
  • Turbulent dynamics
  • Sensor Encapsulation testing
  • Pre and Post calibrations of laser based systems
  • Oceanographic instrument calibrations
  • Radio Frequency link studies
  • Underwater Electric Potential (UEP) studies

Computer Aided Design (CAD) Facility

The Computer Aided Design (CAD) facility at NPOL provides an integrated product development environment. Digital product definition and simulation at this facility offers powerful design tools for mechanical parts in realistic 3D environment. The ability to develop digital prototype models has the advantage of full understanding the product in its design phase with easy links to manufacturing and analysis. The depth and richness of the product information contained in a digital model makes it easier to fully communicate this information to everyone involved in the product development process. Digital model helps to develop and evaluate multiple design concepts. The CAD Software packages include IDEAS, SOLIDWORKS, IRONCAD and AUTOCAD. The facility is networked for efficient use and archiving data.

Prototype Manufacturing Facility

This facility that actively assists prototype manufacture has implemented CAM (Computer Aided Manufacturing) with the aid of a range of modern machinery and expertise. Intricate prototypes with desired accuracy and quality are fabricated in this facility to assist faster execution of sonar project. Direct access to Computer Aided Design data by Numerical Controlled machines in a networked environment is being implemented in this facility.

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