India and Australia Launch Joint Drive to Advance Undersea Surveillance Technology

In a major step toward bolstering maritime security in the Indo-Pacific, India and Australia have entered into a groundbreaking three-year defence research agreement to co-develop advanced undersea surveillance technology. At the heart of this collaboration lies the ambition to improve early detection and tracking of enemy submarines and autonomous underwater vehicles (AUVs), a critical capability in an era of increasingly stealthy underwater threats.

The program brings together two of the region’s foremost defence research institutions — India’s Defence Research and Development Organisation (DRDO) and Australia’s Defence Science and Technology Group (DSTG). Specifically, DRDO’s Naval Physical and Oceanographic Laboratory (NPOL) will work alongside DSTG’s Information Sciences division to jointly design, test, and refine detection systems based on passive acoustic methods.

Listening to the Deep: The Promise of Towed Array Systems

Central to the research is the development and refinement of Towed-Array Target Motion Analysis (TMA) — a technique that uses a long cable of hydrophones to passively “listen” to underwater sound. These arrays can be deployed from submarines or surface ships and are used to detect, classify, and track underwater threats at long ranges without giving away the vessel’s position.

Unlike active sonar, which sends out sound pulses and listens for echoes, passive systems rely entirely on the noise produced by other vessels. This is particularly advantageous for navies aiming to operate discreetly. But making sense of the ocean’s vast and noisy soundscape — filled with marine life, wave action, and civilian ships — requires sophisticated algorithms capable of filtering signals, determining bearing lines, and estimating the motion of targets.

The joint India-Australia program is set to focus heavily on improving these algorithms, ensuring better performance in complex environments where background noise can easily mask vital acoustic signatures.

Shared Expertise, Shared Security

According to Australian defence officials, the program is designed not just as a technology-sharing exercise but as a true co-development effort. Research teams will conduct joint trials, compare acoustic models, and iteratively refine tracking systems based on real-world data gathered from both Indian and Australian waters.

Amanda Bessell, the Australian lead for the collaboration at DSTG, noted, “The science underpinning this initiative is critical to understanding how best to locate submarines while maintaining passive operations. Target Motion Analysis allows vessels to track and monitor undersea targets quietly and precisely.”

India, meanwhile, brings to the table decades of expertise in sonar and undersea technology. DRDO’s NPOL is best known for developing the USHUS sonar suite, a domestically designed system fitted on Indian Navy submarines. The lab is also involved in developing seabed sensor networks, active and passive sonars for surface ships, and advanced signal processing tools for AUVs.

Together, the two nations are looking to push the envelope in terms of both hardware (towed arrays, hydrophone configurations) and software (signal processing, AI-assisted classification, and real-time tracking solutions).

Why This Matters Now

The agreement comes at a time when the undersea domain is becoming increasingly contested. Submarines equipped with air-independent propulsion (AIP), unmanned underwater vehicles with extended range, and deep-sea surveillance drones are changing the dynamics of naval warfare. Nations across the Indo-Pacific are investing heavily in silent and longer-endurance platforms that can operate undetected — raising the stakes for nations like India and Australia to develop superior detection capabilities.

Moreover, as Quad cooperation deepens, particularly in the realm of maritime domain awareness (MDA), this bilateral agreement acts as a technological force multiplier. The results of this collaboration could later be integrated with regional underwater tracking networks, enabling more coordinated responses to undersea incursions.

This is also part of a larger push by both nations to reduce dependence on external suppliers for critical defence technologies and to invest in sovereign capability development. For India, this aligns with the “Atmanirbhar Bharat” (self-reliant India) initiative; for Australia, it ties into its Defence Strategic Review objectives of building long-term capability in the maritime domain.

What Comes Next

Over the next three years, researchers will conduct laboratory simulations, acoustic tank experiments, and at-sea trials. These tests will not only refine the performance of TMA algorithms under different environmental conditions — such as thermal layers, salinity variations, and sea-state noise — but also inform the design of the next generation of towed-array hardware and underwater acoustic processors.

The insights gleaned from this effort are expected to feed directly into the next-generation sonar and surveillance systems for both navies. They may also shape the future of Indian-Australian defence-industrial cooperation, potentially extending into joint production or export-ready solutions for partner countries in the Indo-Pacific.

This undersea surveillance partnership signals a deepening of strategic trust between India and Australia. It’s not just about developing cutting-edge technology — it’s about laying the foundation for a shared maritime security architecture. In a world where the ocean floor is fast becoming the next frontier of defence competition, India and Australia are diving in — together, and with purpose.