The Indian Navy has inducted four underwater sensor systems; Abhay, Humsa-UG, NACS and AIDSS, which have been developed by the country’s research and development arm, Defence Research and Development Organisation (DRDO).

All the four systems have been designed and developed by DRDO’s Kochi-based laboratory, NPOL.

The introduction of the new systems is expected to enhance the underwater surveillance capability of the Indian Navy, as well as promote self-reliance in this field of technology.

"The sonar can detect, localise, classify and track sub-surface and surface targets in both its active and passive modes of operation."

Abhay has been designed as an advanced compact hull mounted active-cum-passive integrated sonar system for smaller platforms, such as shallow water crafts and coastal surveillance / patrol vessels.

Incorporated with the latest technology in hardware architecture and advanced signal processing algorithms, the sonar can detect, localise, classify and track sub-surface and surface targets in both its active and passive modes of operation.

The Indian Navy is planning to install this sonar onto three of the Abhay-class ships.

Developed as an upgrade for the Humsa sonar system, the Humsa-UG features open architecture processor technologies that will allow for smooth upgrade of the system capabilities. This system will be installed on seven ships of three different classes.

The NACS is a near-field acoustic characterisation system that determines the in-situ performance of the sonar systems used to find the frequency-dependent 3D transmission and reception characteristics of the sonar.

It also measures the magnitude and phase characteristics of the sonar transmission and reception electronics, and the transducers.

Integrated with the Humsa-NG sonar array and other naval platforms, NACS will be deployed on all frontline ships.

AIDSS is an advanced indigenous distress sonar system designed as an emergency sound signalling device for the submarine to issue distress alarm and enable quick rescue and salvage.

It transmits sonar signals of a pre-designated frequency and pulse shape in an emergency situation from a submarine for long periods to attract the attention of passive sonars of ships or submarines in the vicinity and all types of standard rescue vessels in operation.

It is also provided with a transponder capability.